83 results on '"Alexander Titz"'
Search Results
2. Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis
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David C. B. Siebert, Roman Sommer, Domen Pogorevc, Michael Hoffmann, Silke C. Wenzel, Rolf Müller, and Alexander Titz
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antibiotic ,argyrin ,mutasynthesis ,nrps ,peptide synthesis ,Science ,Organic chemistry ,QD241-441 - Abstract
The argyrins are secondary metabolites from myxobacteria with antibiotic activity against Pseudomonas aeruginosa. Studying their structure–activity relationship is hampered by the complexity of the chemical total synthesis. Mutasynthesis is a promising approach where simpler and fully synthetic intermediates of the natural product’s biosynthesis can be biotechnologically incorporated. Here, we report the synthesis of a series of tripeptide thioesters as mutasynthons containing the native sequence with a dehydroalanine (Dha) Michael acceptor attached to a sarcosine (Sar) and derivatives. Chemical synthesis of the native sequence ᴅ-Ala-Dha-Sar thioester required revision of the sequential peptide synthesis into a convergent strategy where the thioester with sarcosine was formed before coupling to the Dha-containing dipeptide.
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- 2019
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3. Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections
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Matthew B. Calvert, Varsha R. Jumde, and Alexander Titz
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antimicrobial resistance ,bacterial adhesins ,bacterial toxins ,pathoblockers ,quorum sensing ,Science ,Organic chemistry ,QD241-441 - Abstract
The rapid development of antimicrobial resistance is threatening mankind to such an extent that the World Health Organization expects more deaths from infections than from cancer in 2050 if current trends continue. To avoid this scenario, new classes of anti-infectives must urgently be developed. Antibiotics with new modes of action are needed, but other concepts are also currently being pursued. Targeting bacterial virulence as a means of blocking pathogenicity is a promising new strategy for disarming pathogens. Furthermore, it is believed that this new approach is less susceptible towards resistance development. In this review, recent examples of anti-infective compounds acting on several types of bacterial targets, e.g., adhesins, toxins and bacterial communication, are described.
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- 2018
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4. An efficient synthesis of 1,6-anhydro-N-acetylmuramic acid from N-acetylglucosamine
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Matthew B. Calvert, Christoph Mayer, and Alexander Titz
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N-acetylmuramic acid ,anhydrosugars ,antibiotic resistance ,bacterial cell wall recycling ,carbohydrate synthesis ,Science ,Organic chemistry ,QD241-441 - Abstract
A novel synthesis of 1,6-anhydro-N-acetylmuramic acid is described, which proceeds in only five steps from the cheap starting material N-acetylglucosamine. This efficient synthesis should enable future studies into the importance of 1,6-anhydromuramic acid in bacterial cell wall recycling processes.
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- 2017
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5. O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside
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Roman Sommer, Dirk Hauck, Annabelle Varrot, Anne Imberty, Markus Künzler, and Alexander Titz
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carbohydrate chemistry ,fucose ,lectin ,selenoglycoside ,Science ,Organic chemistry ,QD241-441 - Abstract
Selenoglycosides are used as reactive glycosyl donors in the syntheses of oligosaccharides. In addition, such heavy atom analogs of natural glycosides are useful tools for structure determination of their lectin receptors using X-ray crystallography. Some lectins, e.g., members of the tectonin family, only bind to carbohydrate epitopes with O-alkylated ring hydroxy groups. In this context, we report the first synthesis of an O-methylated selenoglycoside, specifically methyl 2-O-methyl-L-selenofucopyranoside, a ligand of the lectin tectonin-2 from the mushroom Laccaria bicolor. The synthetic route required a strategic revision and further optimization due to the intrinsic lability of alkyl selenoglycosides, in particular for the labile fucose. Here, we describe a successful synthetic access to methyl 2-O-methyl-L-selenofucopyranoside in 9 linear steps and 26% overall yield starting from allyl L-fucopyranoside.
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- 2016
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6. N-Acetylmuramic Acid (MurNAc) Auxotrophy of the Oral Pathogen Tannerella forsythia: Characterization of a MurNAc Kinase and Analysis of Its Role in Cell Wall Metabolism
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Isabel Hottmann, Valentina M. T. Mayer, Markus B. Tomek, Valentin Friedrich, Matthew B. Calvert, Alexander Titz, Christina Schäffer, and Christoph Mayer
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oral pathogen ,red complex consortium ,N-acetylmuramic acid kinase ,MurNAc auxotrophy ,peptidoglycan metabolism ,cell wall recycling ,Microbiology ,QR1-502 - Abstract
Tannerella forsythia is an anaerobic, Gram-negative oral pathogen that thrives in multispecies gingival biofilms associated with periodontitis. The bacterium is auxotrophic for the commonly essential bacterial cell wall sugar N-acetylmuramic acid (MurNAc) and, thus, strictly depends on an exogenous supply of MurNAc for growth and maintenance of cell morphology. A MurNAc transporter (Tf_MurT; Tanf_08375) and an ortholog of the Escherichia coli etherase MurQ (Tf_MurQ; Tanf_08385) converting MurNAc-6-phosphate to GlcNAc-6-phosphate were recently described for T. forsythia. In between the respective genes on the T. forsythia genome, a putative kinase gene is located. In this study, the putative kinase (Tf_MurK; Tanf_08380) was produced as a recombinant protein and biochemically characterized. Kinetic studies revealed Tf_MurK to be a 6-kinase with stringent substrate specificity for MurNAc exhibiting a 6 × 104-fold higher catalytic efficiency (kcat/Km) for MurNAc than for N-acetylglucosamine (GlcNAc) with kcat values of 10.5 s-1 and 0.1 s-1 and Km values of 200 μM and 116 mM, respectively. The enzyme kinetic data suggest that Tf_MurK is subject to substrate inhibition (Ki[S] = 4.2 mM). To assess the role of Tf_MurK in the cell wall metabolism of T. forsythia, a kinase deletion mutant (ΔTf_murK::erm) was constructed. This mutant accumulated MurNAc intracellularly in the exponential phase, indicating the capability to take up MurNAc, but inability to catabolize MurNAc. In the stationary phase, the MurNAc level was reduced in the mutant, while the level of the peptidoglycan precursor UDP-MurNAc-pentapeptide was highly elevated. Further, according to scanning electron microscopy evidence, the ΔTf_murK::erm mutant was more tolerant toward low MurNAc concentration in the medium (below 0.5 μg/ml) before transition from healthy, rod-shaped to fusiform cells occurred, while the parent strain required > 1 μg/ml MurNAc for optimal growth. These data reveal that T. forsythia readily catabolizes exogenous MurNAc but simultaneously channels a proportion of the sugar into peptidoglycan biosynthesis. Deletion of Tf_murK blocks MurNAc catabolism and allows the direction of MurNAc solely to peptidoglycan biosynthesis, resulting in a growth advantage in MurNAc-depleted medium. This work increases our understanding of the T. forsythia cell wall metabolism and may pave new routes for lead finding in the treatment of periodontitis.
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- 2018
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7. Parasite Glycobiology: A Bittersweet Symphony.
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Joao A Rodrigues, Alvaro Acosta-Serrano, Markus Aebi, Michael A J Ferguson, Françoise H Routier, Irene Schiller, Simão Soares, Daniel Spencer, Alexander Titz, Iain B H Wilson, and Luis Izquierdo
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Published
- 2015
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8. A biophysical study with carbohydrate derivatives explains the molecular basis of monosaccharide selectivity of the Pseudomonas aeruginosa lectin LecB.
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Roman Sommer, Thomas E Exner, and Alexander Titz
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Medicine ,Science - Abstract
The rise of resistances against antibiotics in bacteria is a major threat for public health and demands the development of novel antibacterial therapies. Infections with Pseudomonas aeruginosa are a severe problem for hospitalized patients and for patients suffering from cystic fibrosis. These bacteria can form biofilms and thereby increase their resistance towards antibiotics. The bacterial lectin LecB was shown to be necessary for biofilm formation and the inhibition with its carbohydrate ligands resulted in reduced amounts of biofilm. The natural ligands for LecB are glycosides of D-mannose and L-fucose, the latter displaying an unusual strong affinity. Interestingly, although mannosides are much weaker ligands for LecB, they do form an additional hydrogen bond with the protein in the crystal structure. To analyze the individual contributions of the methyl group in fucosides and the hydroxymethyl group in mannosides to the binding, we designed and synthesized derivatives of these saccharides. We report glycomimetic inhibitors that dissect the individual interactions of their saccharide precursors with LecB and give insight into the biophysics of binding by LecB. Furthermore, theoretical calculations supported by experimental thermodynamic data suggest a perturbed hydrogen bonding network for mannose derivatives as molecular basis for the selectivity of LecB for fucosides. Knowledge gained on the mode of interaction of LecB with its ligands at ambient conditions will be useful for future drug design.
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- 2014
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9. New Approaches to Control Infections: Anti-biofilm Strategies against Gram-negative Bacteria
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Roman Sommer, Ines Joachim, Stefanie Wagner, and Alexander Titz
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Adhesion ,Biofilm ,Infection ,Quorum sensing ,Lectins ,Chemistry ,QD1-999 - Abstract
Hospital-acquired bacterial infections, especially with Gram-negative pathogens, present a major threat due to the rapid spread of antibiotic-resistant strains. Targeting mechanisms of bacterial virulence has recently appeared as a promising new therapeutic paradigm. Biofilm formation is a bacterial lifestyle, which offers a survival advantage through its protective matrix against host immune defense and antibiotic treatment. Interfering with biogenesis of adhesive organelles, bacterial communication or carbohydrate-mediated adhesion as anti-biofilm strategies are reviewed.
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- 2013
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10. Caenorhabditis elegans N-glycan core beta-galactoside confers sensitivity towards nematotoxic fungal galectin CGL2.
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Alex Butschi, Alexander Titz, Martin A Wälti, Vincent Olieric, Katharina Paschinger, Katharina Nöbauer, Xiaoqiang Guo, Peter H Seeberger, Iain B H Wilson, Markus Aebi, Michael O Hengartner, and Markus Künzler
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
The physiological role of fungal galectins has remained elusive. Here, we show that feeding of a mushroom galectin, Coprinopsis cinerea CGL2, to Caenorhabditis elegans inhibited development and reproduction and ultimately resulted in killing of this nematode. The lack of toxicity of a carbohydrate-binding defective CGL2 variant and the resistance of a C. elegans mutant defective in GDP-fucose biosynthesis suggested that CGL2-mediated nematotoxicity depends on the interaction between the galectin and a fucose-containing glycoconjugate. A screen for CGL2-resistant worm mutants identified this glycoconjugate as a Galbeta1,4Fucalpha1,6 modification of C. elegans N-glycan cores. Analysis of N-glycan structures in wild type and CGL2-resistant nematodes confirmed this finding and allowed the identification of a novel putative glycosyltransferase required for the biosynthesis of this glycoepitope. The X-ray crystal structure of a complex between CGL2 and the Galbeta1,4Fucalpha1,6GlcNAc trisaccharide at 1.5 A resolution revealed the biophysical basis for this interaction. Our results suggest that fungal galectins play a role in the defense of fungi against predators by binding to specific glycoconjugates of these organisms.
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- 2010
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11. Mimetics of Sialyl Lewisx: The Pre-Organization of the Carboxylic Acid is Essential for Binding to Selectins
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Alexander Titz and Beat Ernst
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Antagonist ,Pre-organization ,Selectin ,Sialyl lewisx ,Sialyl mimetics ,Chemistry ,QD1-999 - Abstract
Selectins play a key role in leukocyte trafficking during the inflammatory response of the organism, i.e. the recruitment and extravasation of leukocytes from the blood stream into inflamed tissue. Antagonizing the interaction of selectins with their physiological ligands was shown to be a validated approach for the treatment of inflammatory disorders like rheumatoid arthritis, stroke or reperfusion injuries. Although numerous research efforts to identify small molecule selectin antagonists have been reported, no successful drug has been identified so far. This mini-review describes selectin antagonists, where the N-acetylneuraminic acid moiety of the natural ligand sialyl Lewisx is replaced by mimetics containing the essential carboxylic acid function. The prerequisite of a pre-organization of the carboxylate in the bioactive conformation is discussed.
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- 2007
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12. Virtual Screening Against Carbohydrate-Binding Proteins: Evaluation and Application to BacterialBurkholderia ambifariaLectin.
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Tamir Dingjan, émilie Gillon, Anne Imberty, Serge Pérez, Alexander Titz, Paul A. Ramsland, and Elizabeth Yuriev
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- 2018
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13. Glycomimetics for the inhibition and modulation of lectins
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Steffen Leusmann, Petra Ménová, Elena Shanin, Alexander Titz, and Christoph Rademacher
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General Chemistry - Abstract
Carbohydrates are essential mediators of many processes in health and disease. The development of glycomimetics as inhibitors and modulators of their lectin receptors has been a success story with numerous molecules reaching clinical stages.
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- 2023
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14. Photorhabdus luminescens lectin A (PllA) : A new probe for detecting α-galactoside-terminating glycoconjugates
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Jesko Koehnke, Eckhard Wolf, Ghamdan Beshr, Asfandyar Sikandar, Dirk Hauck, Alexander Titz, Nikolai Klymiuk, Eva-Maria Jemiller, Stefanie Wagner, and Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Universitycampus E8.1, 66123 Saarbrücken, Germany.
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0301 basic medicine ,chemistry.chemical_classification ,030102 biochemistry & molecular biology ,biology ,Glycoconjugate ,Glycobiology ,Protein subunit ,Ligand binding assay ,Lectin ,Glycobiology and Extracellular Matrices ,Cell Biology ,biology.organism_classification ,Biochemistry ,Molecular biology ,In vitro ,Epitope ,03 medical and health sciences ,030104 developmental biology ,chemistry ,Photorhabdus luminescens ,biology.protein ,Molecular Biology - Abstract
Lectins play important roles in infections by pathogenic bacteria, for example, in host colonization, persistence and biofilm formation. The Gram-negative entomopathogenic bacterium Photorhabdus luminescens symbiotically lives in insect-infecting Heterorhabditis nematodes and kills the insect host upon invasion by the nematode. The P. luminescens genome harbors the gene plu2096 coding for a novel lectin that we named PllA. We analyzed the binding properties of purified PllA with a glycan array and a binding assay in solution. Both assays revealed a strict specificity of PllA for alpha-galactoside-terminating glycoconjugates. The crystal structures of apo PllA and complexes with three different ligands revealed the molecular basis for the strict specificity of this lectin. Furthermore, we found that a 90 degree twist in subunit orientation leads to a peculiar quaternary structure compared with that of its ortholog LecA from Pseudomonas aeruginosa. We also investigated the utility of PllA as a probe for detecting alpha-galactosides. The alpha-Gal epitope is present on wild-type pig cells and the main reason for hyperacute organ rejection in pig to primate xenotransplantation. We noted that PllA specifically recognizes this epitope on the glycan array and demonstrated that PllA can be used as a fluorescent probe to detect this epitope on primary porcine cells in vitro. In summary, our biochemical and structural analyses of the P. luminescens lectin PllA have disclosed the structural basis for PllAs high specificity for alpha-galactoside-containing ligands, and we show that PllA can be used to visualize alpha-Gal epitope on porcine tissues.
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- 2023
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15. Glycomimetic, Orally Bioavailable LecB Inhibitors Block Biofilm Formation of Pseudomonas aeruginosa
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Anne Imberty, Katharina Rox, Thomas Brunner, Stefanie Wagner, Janine Schreiber, Rolf W. Hartmann, Alexander Titz, Annabelle Varrot, Mark Brönstrup, Dirk Hauck, Thomas Ryckmans, Eike-Christian Wamhoff, Roman Sommer, Christoph Rademacher, Centre de Recherches sur les Macromolécules Végétales (CERMAV ), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Division of Immunopathology, University of Bern, Department of Biomolecular Systems [Potsdam], Max Planck Institute of Colloids and Interfaces, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Jena Optronik GmbH (Jena Optronik), and entreprise
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0301 basic medicine ,education ,Molecular Conformation ,Carbohydrates ,Administration, Oral ,Biological Availability ,Peptides and proteins ,medicine.disease_cause ,Ligands ,Biochemistry ,Catalysis ,Microbiology ,Structure-Activity Relationship ,03 medical and health sciences ,Colloid and Surface Chemistry ,In vivo ,Glycomimetic ,Lectins ,medicine ,[CHIM]Chemical Sciences ,Pathogen ,Sulfonamides ,Dose-Response Relationship, Drug ,biology ,Chemistry ,Pseudomonas aeruginosa ,Inhibitors ,Biofilm ,General Chemistry ,biology.organism_classification ,In vitro ,3. Good health ,Bioavailability ,Kinetics ,030104 developmental biology ,Cinnamates ,Biofilms ,Thermodynamics ,Bacteria - Abstract
International audience; The opportunistic Gram-negative bacterium Pseudomonas aeruginosa is a leading pathogen for infections of immuno-compromised patients and those suffering from cystic fibrosis. Its ability to switch from planktonic life to aggregates, forming the so-called biofilms, is a front-line mechanism of antimicrobial resistance. The bacterial carbohydrate binding protein LecB is an integral component and necessary for biofilm formation. Here, we report a new class of drug-like low molecular weight inhibitors of the lectin LecB with nanomolar affinities and excellent receptor binding kinetics and thermodynamics. This class of glycomimetic inhibitors efficiently blocked biofilm formation of P. aeruginosa in vitro while the natural monovalent carbohydrate ligands failed. Furthermore, excellent selectivity and pharmacokinetic properties were achieved. Notably, two compounds showed good oral bioavailability, and high compound concentrations in plasma and urine were achieved in vivo.
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- 2023
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16. Virtual Screening Against Carbohydrate-Binding Proteins : Evaluation and Application to Bacterial Burkholderia ambifaria Lectin
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Alexander Titz, Elizabeth Yuriev, Emilie Gillon, Paul A. Ramsland, Serge Pérez, Anne Imberty, Tamir Dingjan, HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany., Centre de Recherches sur les Macromolécules Végétales (CERMAV ), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Département de pharmacochimie moléculaire (DPM )
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0301 basic medicine ,Models, Molecular ,Burkholderia ,Protein Conformation ,General Chemical Engineering ,Carbohydrates ,Receptors, Cell Surface ,Peptides and proteins ,Library and Information Sciences ,01 natural sciences ,Microbiology ,Small Molecule Libraries ,03 medical and health sciences ,Bacterial Proteins ,Lectins ,Bacteriology ,[CHIM]Chemical Sciences ,Carbohydrate-responsive element-binding protein ,Gene ,ComputingMilieux_MISCELLANEOUS ,Inhibition ,Virtual screening ,Binding Sites ,biology ,010405 organic chemistry ,Inhibitors ,Burkholderia ambifaria ,Lectin ,General Chemistry ,biology.organism_classification ,0104 chemical sciences ,Computer Science Applications ,Zinc ,030104 developmental biology ,Pseudomonas aeruginosa ,biology.protein - Abstract
Bacterial adhesion to human epithelia via lectins constitutes a therapeutic opportunity to prevent infection. Specifically, BambL (the lectin from Burkholderia ambifaria) is implicated in cystic fibrosis, where lectin-mediated bacterial adhesion to fucosylated lung epithelia is suspected to play an important role. We employed structure-based virtual screening to identify inhibitors of BambL-saccharide interaction with potential therapeutic value. To enable such discovery, a virtual screening protocol was iteratively developed via 194 retrospective screening protocols against 4 bacterial lectins (BambL, BC2L-A, FimH, and LecA) with known ligands. Specific attention was given to the rigorous evaluation of retrospective screening, including calculation of analytical errors for enrichment metrics. The developed virtual screening workflow used crystallographic constraints, pharmacophore filters, and a final manual selection step. The protocol was applied to BambL, predicting 15 active compounds from virtual libraries of approximately 7 million compounds. Experimental validation using fluorescence polarization confirmed micromolar inhibitory activity for two compounds, which were further characterized by isothermal titration calorimetry and surface plasmon resonance. Subsequent testing against LecB from Pseudomonas aeruginosa demonstrated binding specificity of one of the hit compounds. This report demonstrates the utility of virtual screening protocols, integrating ligand-based pharmacophore filtering and structure-based constraints, in the search for bacterial lectin inhibitors.
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- 2023
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17. NamZ1 and NamZ2 from the Oral Pathogen Tannerella forsythia Are Peptidoglycan Processing Exo-β-N-Acetylmuramidases with Distinct Substrate Specificities
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Marina Borisova, Katja Balbuchta, Andrew Lovering, Alexander Titz, and Christoph Mayer
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exo-lytic muramidase ,disaccharidase ,CAZy glycosidase ,Bacteroidetes ,Peptidoglycan ,cell wall recycling ,Disaccharides ,Microbiology ,Acetylglucosamine ,Substrate Specificity ,pNP-MurNAc ,Cell Wall ,peptidoglycan salvage ,Tannerella forsythia ,family GH171 ,glycoside hydrolase ,carbohydrate metabolism ,N-acetylmuramic acid (MurNAc) ,MurNAc auxotrophy ,Molecular Biology ,Research Article ,Bacillus subtilis - Abstract
The Gram-negative periodontal pathogen Tannerella forsythia is inherently auxotrophic for N-acetylmuramic acid (MurNAc), which is an essential carbohydrate constituent of the peptidoglycan (PGN) of the bacterial cell wall. Thus, to build up its cell wall, T. forsythia strictly depends on the salvage of exogenous MurNAc or sources of MurNAc, such as polymeric or fragmentary PGN, derived from cohabiting bacteria within the oral microbiome. In our effort to elucidate how T. forsythia satisfies its demand for MurNAc, we recognized that the organism possesses three putative orthologs of the exo-β-N-acetylmuramidase BsNamZ from Bacillus subtilis, which cleaves nonreducing end, terminal MurNAc entities from the artificial substrate pNP-MurNAc and the naturally-occurring disaccharide substrate MurNAc-N-acetylglucosamine (MurNAc-GlcNAc). TfNamZ1 and TfNamZ2 were successfully purified as soluble, pure recombinant His(6)-fusions and characterized as exo-lytic β-N-acetylmuramidases with distinct substrate specificities. The activity of TfNamZ1 was considerably lower compared to TfNamZ2 and BsNamZ, in the cleavage of MurNAc-GlcNAc. When peptide-free PGN glycans were used as substrates, we revealed striking differences in the specificity and mode of action of these enzymes, as analyzed by mass spectrometry. TfNamZ1, but not TfNamZ2 or BsNamZ, released GlcNAc-MurNAc disaccharides from these glycans. In addition, glucosamine (GlcN)-MurNAc disaccharides were generated when partially N-deacetylated PGN glycans from B. subtilis 168 were applied. This characterizes TfNamZ1 as a unique disaccharide-forming exo-lytic β-N-acetylmuramidase (exo-disaccharidase), and, TfNamZ2 and BsNamZ as sole MurNAc monosaccharide-lytic exo-β-N-acetylmuramidases. IMPORTANCE Two exo-N-acetylmuramidases from T. forsythia belonging to glycosidase family GH171 (www.cazy.org) were shown to differ in their activities, thus revealing a functional diversity within this family: NamZ1 releases disaccharides (GlcNAc-MurNAc/GlcN-MurNAc) from the nonreducing ends of PGN glycans, whereas NamZ2 releases terminal MurNAc monosaccharides. This work provides a better understanding of how T. forsythia may acquire the essential growth factor MurNAc by the salvage of PGN from cohabiting bacteria in the oral microbiome, which may pave avenues for the development of anti-periodontal drugs. On a broad scale, our study indicates that the utilization of PGN as a nutrient source, involving exo-lytic N-acetylmuramidases with different modes of action, appears to be a general feature of bacteria, particularly among the phylum Bacteroidetes.
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- 2023
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18. Pseudomonas aeruginosa <scp>LecB</scp> suppresses immune responses by inhibiting transendothelial migration
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Janina Sponsel, Yubing Guo, Lutfir Hamzam, Alice C Lavanant, Annia Pérez‐Riverón, Emma Partiot, Quentin Muller, Julien Rottura, Raphael Gaudin, Dirk Hauck, Alexander Titz, Vincent Flacher, Winfried Römer, and Christopher G Mueller
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Genetics ,Molecular Biology ,Biochemistry - Published
- 2023
19. A rapid synthesis of low-nanomolar divalent LecA inhibitors in four linear steps from d-galactose pentaacetate
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Eva Zahorska, Alexander Titz, Sakonwan Kuhaudomlarp, Martin Lepšík, Saverio Minervini, Anne Imberty, Anna K. H. Hirsch, Sultaan Yousaf, Thorsten Kinsinger, Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
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Models, Molecular ,Protein Conformation ,Chemistry Techniques, Synthetic ,010402 general chemistry ,medicine.disease_cause ,01 natural sciences ,Catalysis ,Virulence factor ,Epitope ,Divalent ,Protein structure ,Materials Chemistry ,medicine ,[CHIM]Chemical Sciences ,Adhesins, Bacterial ,ComputingMilieux_MISCELLANEOUS ,chemistry.chemical_classification ,biology ,010405 organic chemistry ,Chemistry ,Pseudomonas aeruginosa ,Metals and Alloys ,Biofilm ,Lectin ,Galactose ,General Chemistry ,0104 chemical sciences ,3. Good health ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Bacterial adhesin ,Kinetics ,Biochemistry ,Ceramics and Composites ,biology.protein - Abstract
Chronic infections with Pseudomonas aeruginosa are associated with the formation of bacterial biofilms. The tetrameric P. aeruginosa lectin LecA is a virulence factor and an anti-biofilm drug target. Increasing the overall binding affinity by multivalent presentation of binding epitopes can enhance the weak carbohydrate-ligand interactions. Low-nanomolar divalent LecA ligands/inhibitors with up to 260-fold valency-normalized potency boost and excellent selectivity over human galectin-1 were synthesized from d-galactose pentaacetate and benzaldehyde-based linkers in four linear steps.
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- 2023
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20. β-Boronic Acid-Substituted Bodipy Dyes for Fluorescence Anisotropy Analysis of Carbohydrate Binding
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Caroline Hoffmann, Matthias Jourdain, Alexander Grandjean, Alexander Titz, and Gregor Jung
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Boron Compounds ,Diols ,Magnetic properties ,Organic compounds ,Phosphotransferases ,Carbohydrates ,Fluorescence Polarization ,Boronic Acids ,Fluorescence ,Fluorescent Dyes ,Analytical Chemistry - Abstract
Boronic acids are widely used for labeling catechols and carbohydrates in analytical (bio)chemistry due to their high binding affinities for diols. Here, we present two asymmetrically substituted Bodipy dyes with a boronic acid at the β-position (BBB). We present a green-emitting BBB, gBBB, and, by expanding the conjugated system of the Bodipy core at α-position, a red-emitting rBBB. Especially, gBBB shows a bathochromic shift of the electronic spectra upon binding to saccharides and polyols, whereas the fluorescence lifetime of rBBB is more sensitive to hydroxy-ligand binding. Moreover, gBBB constantly shows higher binding affinities than rBBB, reaching
- Published
- 2022
21. Prototyping and Engineering Model Test Campaign of the 100W 1U PowerCube Deployable Solar Array
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Antonio Pedivellano, Thomas Sinn, Ambre Raharijaona, Michael Kringer, Joram Gruber, Joachim Schmidt, Thomas Lund, Alexander Titz, Diego Garcia, Daria Stepanova, Anton Drachuk, Anton Vlaskin, Tim Kubera, Stefan Titze, Mathias Hartmann, Bailey L. Garrett, Callan Whitney, and Pauline Faure
- Published
- 2023
22. Neutralizing the Impact of the Virulence Factor LecA from Pseudomonas aeruginosa on Human Cells with New Glycomimetic Inhibitors
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Eva Zahorska, Francesca Rosato, Kai Stober, Sakonwan Kuhaudomlarp, Joscha Meiers, Dirk Hauck, Dorina Reith, Emilie Gillon, Katharina Rox, Anne Imberty, Winfried Römer, Alexander Titz, Helmholtz-Zentrum für Infektionsforschung GmbH (HZI), Universität des Saarlandes [Saarbrücken], Albert-Ludwigs-Universität Freiburg, Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Helmholtz Centre for Infection Research (HZI), ANR-17-CE11-0048,GLYCOMIME,Developement de glycomimétiques non glucidiques contre les lectines bactériennes(2017), ANR-15-IDEX-0002,UGA,IDEX UGA(2015), ANR-17-EURE-0003,CBH-EUR-GS,CBH-EUR-GS(2017), and European Project: 814029 ,SynBioCarb
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[CHIM.THER]Chemical Sciences/Medicinal Chemistry ,General Chemistry ,Catalysis - Abstract
International audience; Bacterial adhesion, biofilm formation and host cell invasion of the ESKAPE pathogen Pseudomonas aeruginosa require the tetravalent lectins LecA and LecB, which are therefore drug targets to fight these infections. Recently, we have reported highly potent divalent galactosides as specific LecA inhibitors. However, they suffered from very low solubility and an intrinsic chemical instability due to two acylhydrazone motifs, which precluded further biological evaluation. Here, we isosterically substituted the acylhydrazones and systematically varied linker identity and length between the two galactosides necessary for LecA binding. The optimized divalent LecA ligands showed improved stability and were up to 5000-fold more soluble. Importantly, these properties now enabled their biological characterization. The lead compound L2 potently inhibited LecA binding to lung epithelial cells, restored wound closure in a scratch assay and reduced the invasiveness of P. aeruginosa into host cells.
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- 2023
23. Neutralisation der Auswirkungen des Virulenzfaktors LecA aus Pseudomonas aeruginosa auf Humanzellen durch neue glykomimetische Inhibitoren
- Author
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Eva Zahorska, Francesca Rosato, Kai Stober, Sakonwan Kuhaudomlarp, Joscha Meiers, Dirk Hauck, Dorina Reith, Emilie Gillon, Katharina Rox, Anne Imberty, Winfried Römer, and Alexander Titz
- Subjects
General Medicine - Published
- 2023
24. Short Peptides and Their Mimetics as Potent Antibacterial Agents and Antibiotic Adjuvants
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Sandeep Verma, Grace Kaul, Apurva Panjla, Alexander Titz, and Sidharth Chopra
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Cell Membrane Permeability ,medicine.drug_class ,Antibiotics ,Antimicrobial peptides ,Molecular Conformation ,Peptide ,Context (language use) ,Microbial Sensitivity Tests ,Antibacterial efficacy ,Pharmacology ,Peptides, Cyclic ,Biochemistry ,Structure-Activity Relationship ,Antibiotic resistance ,Adjuvants, Immunologic ,Anti-Infective Agents ,Drug Development ,Biomimetic Materials ,Humans ,Medicine ,Amino Acid Sequence ,Polymyxins ,chemistry.chemical_classification ,business.industry ,General Medicine ,Antimicrobial ,Multiple drug resistance ,chemistry ,Molecular Medicine ,business ,Antimicrobial Cationic Peptides - Abstract
Antimicrobial resistance (AMR) has been increasing unrelentingly worldwide, thus negatively impacting human health. The discovery and development of novel antibiotics is an urgent unmet need of the hour. However, it has become more challenging, requiring increasingly time-consuming efforts with increased commercial risks. Hence, alternative strategies are urgently needed to potentiate the existing antibiotics. In this context, short cationic peptides or peptide-based antimicrobials that mimic the activity of naturally occurring antimicrobial peptides (AMPs) could overcome the disadvantages of AMPs having evolved as potent antibacterial agents. Besides their potent antibacterial efficacy, short peptide conjugates have also gained attention as potent adjuvants to conventional antibiotics. Such peptide antibiotic combinations have become an increasingly cost-effective therapeutic option to tackle AMR. This Review summarizes the recent progress for peptide-based small molecules as promising antimicrobials and as adjuvants for conventional antibiotics to counter multidrug resistant (MDR) pathogens.
- Published
- 2021
25. Pineapple Lectin AcmJRL Binds SARS-CoV-2 Spike Protein in a Carbohydrate-Dependent Fashion
- Author
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Sebastian Adam, Rolf Müller, Jan Dastbaz, Joscha Meiers, Alexander Titz, Peter Gross, Susanne Kirsch, Sari Rasheed, and Peter Meiser
- Subjects
Organic Chemistry ,Molecular Medicine ,Molecular Biology ,Biochemistry - Abstract
The highly glycosylated spike protein of SARS-CoV-2 is essential for infection and constitutes a prime target for antiviral agents and vaccines. The pineapple-derived jacalin-related lectin AcmJRL is present in the medication bromelain in significant quantities and has previously been described to bind mannosides. Here, we performed a large ligand screening of AcmJRL by glycan array analysis, quantified the interaction with carbohydrates and validated high-mannose glycans as preferred ligands. Because the SARS-CoV-2 spike protein was previously reported to carry a high proportion of high-mannose N-glycans, we tested the binding of AcmJRL to the recombinantly produced extraviral domain of spike protein. We could demonstrate that AcmJRL binds the spike protein with a low-micromolar K
- Published
- 2022
26. Discovery of
- Author
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Patrycja, Mała, Eike, Siebs, Joscha, Meiers, Katharina, Rox, Annabelle, Varrot, Anne, Imberty, and Alexander, Titz
- Subjects
Mice ,Sulfonamides ,Lectins ,Biofilms ,Pseudomonas aeruginosa ,Thiourea ,Humans ,Animals ,Ligands ,Amides ,Anti-Bacterial Agents - Abstract
The Gram-negative pathogen
- Published
- 2022
27. Lectin-Targeted Prodrugs Activated by
- Author
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Joscha, Meiers, Katharina, Rox, and Alexander, Titz
- Subjects
Virulence Factors ,Lectins ,Biofilms ,Pseudomonas aeruginosa ,Humans ,Prodrugs ,Pseudomonas Infections ,Anti-Bacterial Agents ,Fluoroquinolones - Abstract
Chronic
- Published
- 2022
28. Directing Drugs to Bugs: Antibiotic-Carbohydrate Conjugates Targeting Biofilm-Associated Lectins of Pseudomonas aeruginosa
- Author
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Alexander Titz, Joscha Meiers, Teresa Röhrig, Eva Zahorska, Stefanie Wagner, Dirk Hauck, and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
- Subjects
Drug ,medicine.drug_class ,media_common.quotation_subject ,Antibiotics ,Peptides and proteins ,medicine.disease_cause ,01 natural sciences ,Assays ,Microbiology ,03 medical and health sciences ,Antibiotic resistance ,Drug Discovery ,medicine ,030304 developmental biology ,media_common ,0303 health sciences ,Conjugate acid-base pairs ,biology ,Chemistry ,Pseudomonas aeruginosa ,Biofilm ,Lectin ,biochemical phenomena, metabolism, and nutrition ,Antimicrobial agents ,0104 chemical sciences ,3. Good health ,Ciprofloxacin ,010404 medicinal & biomolecular chemistry ,Biofilms ,Drug delivery ,biology.protein ,Molecular Medicine ,medicine.drug - Abstract
Chronic infections by Pseudomonas aeruginosa are characterized by biofilm formation, which effectively enhances resistance toward antibiotics. Biofilm-specific antibiotic delivery could locally increase drug concentration to break antimicrobial resistance and reduce the drug's peripheral side effects. Two extracellular P. aeruginosa lectins, LecA and LecB, are essential structural components for biofilm formation and thus render a possible anchor for biofilm-targeted drug delivery. The standard-of-care drug ciprofloxacin suffers from severe systemic side effects and was therefore chosen for this approach. We synthesized several ciprofloxacin-carbohydrate conjugates and established a structure-activity relationship. Conjugation of ciprofloxacin to lectin probes enabled biofilm accumulation in vitro, reduced the antibiotic's cytotoxicity, but also reduced its antibiotic activity against planktonic cells due to a reduced cell permeability and on target activity. This work defines the starting point for new biofilm/lectin-targeted drugs to modulate antibiotic properties and ultimately break antimicrobial resistance.
- Published
- 2020
29. Protein-observed 19F NMR of LecA from Pseudomonas aeruginosa
- Author
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Hengxi Zhang, Alexander Titz, Christoph Rademacher, Ines Joachim, Eike Siebs, Daniel Varón Silva, Elena Shanina, and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
- Subjects
Models, Molecular ,Stereochemistry ,AcademicSubjects/SCI01000 ,Fluorine-19 NMR ,010402 general chemistry ,medicine.disease_cause ,01 natural sciences ,Biochemistry ,drug discovery ,Fluorine-19 Magnetic Resonance Imaging ,Structural Biology ,Glycomimetic ,Drug Discovery ,LecA ,Nmr titration ,Carbohydrate Conformation ,medicine ,Adhesins, Bacterial ,biology ,010405 organic chemistry ,Drug discovery ,Pseudomonas aeruginosa ,Chemistry ,Biofilm ,Lectin ,500 Naturwissenschaften und Mathematik::570 Biowissenschaften ,Biologie::570 Biowissenschaften ,Biologie ,Ligand (biochemistry) ,Recombinant Proteins ,NMR ,0104 chemical sciences ,biology.protein ,lectin - Abstract
The carbohydrate-binding protein LecA (PA-IL) from Pseudomonas aeruginosa plays an important role in the formation of biofilms in chronic infections. Development of inhibitors to disrupt LecA-mediated biofilms is desired but it is limited to carbohydrate-based ligands. Moreover, discovery of drug-like ligands for LecA is challenging because of its weak affinities. Therefore, we established a protein-observed 19F (PrOF) nuclear magnetic resonance (NMR) to probe ligand binding to LecA. LecA was labeled with 5-fluoroindole to incorporate 5-fluorotryptophanes and the resonances were assigned by site-directed mutagenesis. This incorporation did not disrupt LecA preference for natural ligands, Ca2+ and d-galactose. Following NMR perturbation of W42, which is located in the carbohydrate-binding region of LecA, allowed to monitor binding of low-affinity ligands such as N-acetyl d-galactosamine (d-GalNAc, Kd = 780 ± 97 μM). Moreover, PrOF NMR titration with glycomimetic of LecA p-nitrophenyl β-d-galactoside (pNPGal, Kd = 54 ± 6 μM) demonstrated a 6-fold improved binding of d-Gal proving this approach to be valuable for ligand design in future drug discovery campaigns that aim to generate inhibitors of LecA.
- Published
- 2020
30. Nano-in-Microparticles for Aerosol Delivery of Antibiotic-Loaded, Fucose-Derivatized, and Macrophage-Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery
- Author
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Benedikt C. Huck, Durairaj Thiyagarajan, Aghiad Bali, Annette Boese, Karen F. W. Besecke, Constantin Hozsa, Robert K. Gieseler, Marcus Furch, Cristiane Carvalho‐Wodarz, Franziska Waldow, Dominik Schwudke, Olga Metelkina, Alexander Titz, Hanno Huwer, Konrad Schwarzkopf, Jessica Hoppstädter, Alexandra K. Kiemer, Marcus Koch, Brigitta Loretz, and Claus‐Michael Lehr
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Biomaterials ,Aerosols ,Macrophages ,Administration, Inhalation ,Liposomes ,Biomedical Engineering ,Pharmaceutical Science ,Dry Powder Inhalers ,Particle Size ,Powders ,Lung ,Anti-Bacterial Agents ,Fucose - Abstract
Nontuberculous mycobacterial infections rapidly emerge and demand potent medications to cope with resistance. In this context, targeted loco-regional delivery of aerosol medicines to the lungs is an advantage. However, sufficient antibiotic delivery requires engineered aerosols for optimized deposition. Here, the effect of bedaquiline-encapsulating fucosylated versus nonfucosylated liposomes on cellular uptake and delivery is investigated. Notably, this comparison includes critical parameters for pulmonary delivery, i.e., aerosol deposition and the noncellular barriers of pulmonary surfactant (PS) and mucus. Targeting increases liposomal uptake into THP-1 cells as well as peripheral blood monocyte- and lung-tissue derived macrophages. Aerosol deposition in the presence of PS, however, masks the effect of active targeting. PS alters antibiotic release that depends on the drug's hydrophobicity, while mucus reduces the mobility of nontargeted more than fucosylated liposomes. Dry-powder microparticles of spray-dried bedaquiline-loaded liposomes display a high fine particle fraction of70%, as well as preserved liposomal integrity and targeting function. The antibiotic effect is maintained when deposited as powder aerosol on cultured Mycobacterium abscessus. When treating M. abscessus infected THP-1 cells, the fucosylated variant enabled enhanced bacterial killing, thus opening up a clear perspective for the improved treatment of nontuberculous mycobacterial infections.
- Published
- 2022
31. Targeting extracellular lectins of
- Author
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Olga, Metelkina, Benedikt, Huck, Jonathan S, O'Connor, Marcus, Koch, Andreas, Manz, Claus-Michael, Lehr, and Alexander, Titz
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Biofilms ,Lectins ,Liposomes ,Materials Testing ,Pseudomonas aeruginosa ,Microbial Sensitivity Tests ,Anti-Bacterial Agents - Abstract
The antimicrobial resistance crisis requires novel approaches for the therapy of infections especially with Gram-negative pathogens.
- Published
- 2022
32. Concept trade-off and detailed design of a 1U NanoSat 100W deployable solar array and it’s in-orbit demonstration preparation
- Author
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Thomas Sinn, Thomas Lund, Joram Gruber, Alexander Titz, and Ambre Raharijaona
- Published
- 2022
33. Correction: Concept trade-off and detailed design of a 1U NanoSat 100W deployable solar array and it’s in-orbit demonstration preparation
- Author
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Antonio Pedivellano, Thomas Sinn, Thomas Lund, Joram Gruber, Alexander Titz, Ambre Raharijaona, Michael Kringer, Joachim Schmidt, Purav Parekh, Manuel A. Garcia Gutierrez, Daria Stepanova, Anton Drachuk, Anton Vlaskin, Tim Kubera, Stefan Titze, and Mathias Hartmann
- Published
- 2022
34. Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis
- Author
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Roman Sommer, Silke C. Wenzel, Alexander Titz, David Chan Bodin Siebert, Domen Pogorevc, Rolf Müller, Michael J. Hoffmann, and BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany.
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Sarcosine ,Stereochemistry ,Tripeptide ,Thioester ,01 natural sciences ,Chemical synthesis ,Full Research Paper ,argyrin ,lcsh:QD241-441 ,03 medical and health sciences ,chemistry.chemical_compound ,lcsh:Organic chemistry ,Dehydroalanine ,mutasynthesis ,antibiotic ,nrps ,peptide synthesis ,Peptide synthesis ,lcsh:Science ,030304 developmental biology ,chemistry.chemical_classification ,0303 health sciences ,Dipeptide ,010405 organic chemistry ,NRPS ,Organic Chemistry ,Total synthesis ,food and beverages ,0104 chemical sciences ,Chemistry ,chemistry ,lipids (amino acids, peptides, and proteins) ,lcsh:Q - Abstract
The argyrins are secondary metabolites from myxobacteria with antibiotic activity against Pseudomonas aeruginosa. Studying their structure–activity relationship is hampered by the complexity of the chemical total synthesis. Mutasynthesis is a promising approach where simpler and fully synthetic intermediates of the natural product’s biosynthesis can be biotechnologically incorporated. Here, we report the synthesis of a series of tripeptide thioesters as mutasynthons containing the native sequence with a dehydroalanine (Dha) Michael acceptor attached to a sarcosine (Sar) and derivatives. Chemical synthesis of the native sequence ᴅ-Ala-Dha-Sar thioester required revision of the sequential peptide synthesis into a convergent strategy where the thioester with sarcosine was formed before coupling to the Dha-containing dipeptide.
- Published
- 2019
35. NamZ1 and NamZ2 from the oral pathogen Tannerella forsythia are peptidoglycan processing exo-β-N-acetylmuramidases with distinct substrate specificity
- Author
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Andrew L. Lovering, Alexander Titz, Katja Balbuchta, Christoph Mayer, and Marina Borisova
- Subjects
Glycan ,biology ,Chemistry ,Bacillus subtilis ,biology.organism_classification ,Bacterial cell structure ,Cell wall ,chemistry.chemical_compound ,Forsythia ,Biochemistry ,biology.protein ,Tannerella forsythia ,Glycoside hydrolase ,Peptidoglycan - Abstract
The Gram-negative periodontal pathogen Tannerella forsythia is inherently auxotrophic for N-acetylmuramic acid (MurNAc), which is an essential carbohydrate constituent of the peptidoglycan (PGN) of the bacterial cell wall. Thus, to build up its cell wall, T. forsythia strictly depends on the salvage of exogenous MurNAc or sources of MurNAc, such as polymeric or fragmentary PGN, derived from cohabiting bacteria within the oral microbiome. In our effort to elucidate how T. forsythia satisfies its demand for MurNAc, we recognized that the organism possesses three putative orthologs of the exo-β-N-acetylmuramidase BsNamZ from Bacillus subtilis, which cleaves non-reducing end, terminal MurNAc entities from the artificial substrate pNP-MurNAc and the naturally-occurring disaccharide substrate MurNAc-β-1,4-N-acetylglucosamine (GlcNAc). TfNamZ1 and TfNamZ2 were successfully purified as soluble, pure recombinant His6-fusions and characterized as exo-lytic β-N-acetylmuramidases with distinct substrate specificities. The activity of TfNamZ1 was considerably lower compared to TfNamZ2 and BsNamZ, in the cleavage of pNP-MurNAc and MurNAc-GlcNAc. When peptide-free PGN glycans were used as substrates, we revealed striking differences in the specificity and mode of action of these enzymes, as analyzed by mass spectrometry. TfNamZ1, but not TfNamZ2 or BsNamZ, released GlcNAc-MurNAc disaccharides from these glycans. In addition, glucosamine (GlcN)-MurNAc disaccharides were generated when partially N-deacetylated PGN glycans from B. subtilis 168 were applied. This characterizes TfNamZ1 as a unique disaccharide-forming exo-lytic β-N-acetylmuramidase (exo-disaccharidase), and, TfNamZ2 and BsNamZ as sole MurNAc monosaccharide-lytic exo-β-N-acetylmuramidases.IMPORTANCETwo exo-β-N-acetylmuramidases from T. forsythia belonging to glycosidase family GH171 (www.cazy.org) were shown to differ in their activities, thus revealing a functional diversity within this family: NamZ1 releases disaccharides (GlcNAc-MurNAc/GlcN-MurNAc) from the non-reducing ends of PGN glycans, whereas NamZ2 releases terminal MurNAc monosaccharides. This work provides a better understanding of how T. forsythia may acquire the essential growth factor MurNAc by the salvage of PGN from cohabiting bacteria in the oral microbiome, which may pave avenues for the development of anti-periodontal drugs. On a broad scale, our study indicates that the utilization of PGN as a nutrient source, involving exo-lytic N-acetylmuramidases with different modes of action, appears to be a general feature of bacteria, particularly among the phylum Bacteroidetes.
- Published
- 2021
36. Targeting the Central Pocket of the Pseudomonas aeruginosa Lectin LecA
- Author
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Peter H. Seeberger, Elena Shanina, Cloé Fortin, Sakonwan Kuhaudomlarp, Didier Rognan, Priscila da Silva Figueiredo Celestino Gomes, Eike Siebs, Anne Imberty, Alexander Titz, Christoph Rademacher, Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Department of Colloid Chemistry [Potsdam], Max Planck Institute of Colloids and Interfaces, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire d'Innovation Thérapeutique (LIT), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC), ANR-17-CE11-0048,GLYCOMIME,Developement de glycomimétiques non glucidiques contre les lectines bactériennes(2017), and ANR-15-IDEX-0002,UGA,IDEX UGA(2015)
- Subjects
Models, Molecular ,Carbohydrates ,Virulence ,Microbial Sensitivity Tests ,medicine.disease_cause ,01 natural sciences ,Biochemistry ,Microbiology ,03 medical and health sciences ,Structure-Activity Relationship ,LecA ,medicine ,[CHIM]Chemical Sciences ,Mode of action ,Adhesins, Bacterial ,Molecular Biology ,Pathogen ,030304 developmental biology ,glycoconjugate ,0303 health sciences ,biology ,Dose-Response Relationship, Drug ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Pseudomonas aeruginosa ,Organic Chemistry ,Biofilm ,Lectin ,Biofilm matrix ,500 Naturwissenschaften und Mathematik::570 Biowissenschaften ,Biologie::570 Biowissenschaften ,Biologie ,biology.organism_classification ,glycoconjugates ,0104 chemical sciences ,Anti-Bacterial Agents ,Biofilms ,LecA 2 ,biology.protein ,glycomimetics ,Molecular Medicine ,lectin ,Bacteria - Abstract
International audience; Pseudomonas aeruginosa is an opportunistic ESKAPE pathogen that produces two lectins, LecA and LecB, as part of its large arsenal of virulence factors. Both carbohydrate-binding proteins are central to the initial and later persistent infection processes, i.e. bacterial adhesion and biofilm formation. The biofilm matrix is a major resistance determinant and protects the bacteria against external threats such as the host immune system or antibiotic treatment. Therefore, the development of drugs against the P. aeruginosa biofilm is of particular interest to restore efficacy of antimicrobials. Carbohydrate-based inhibitors for LecA and LecB were previously shown to efficiently reduce biofilm formations. Here, we report a new approach for inhibiting LecA with synthetic molecules bridging the established carbohydrate-binding site and a central cavity located between two LecA protomers of the lectin tetramer. Inspired by in silico design, we synthesized various galactosidic LecA inhibitors with aromatic moities targeting this central pocket. These compounds reached low micromolar affinities, validated in different biophysical assays. Finally, X-ray diffraction analysis revealed the interactions of this compound class with LecA. This new mode of action paves the way to a novel route towards inhibition of P. aeruginosa biofilms.
- Published
- 2021
37. Towards the sustainable discovery and development of new antibiotics
- Author
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Ian H. Gilbert, Kenneth Pfarr, Timo Jaeger, Mika Lindvall, Anders Karlén, Philippe Glaser, Jennifer Herrmann, Marco Pieroni, Bertrand Aigle, Evi Stegmann, Heather Graz, Andrea Schiefer, Jean-Luc Pernodet, Thomas Hesterkamp, Rui Moreira, Heike Brötz-Oesterhelt, Andrew W. Truman, Andreas Keller, Ludovic Halby, Alexander Titz, José R. Tormo, Michael Graz, Kira J. Weissman, Olga Genilloud, Marc Stadler, Claus-Michael Lehr, Paola B. Arimondo, Mark Brönstrup, Savithri Ramurthy, Eriko Takano, Frédéric Peyrane, Mathias Winterhalter, Marnix H. Medema, Maarten van Dongen, Anna K. H. Hirsch, Achim Hoerauf, Helge B. Bode, Laurent Fraisse, Laura J. V. Piddock, Martin Empting, Brigitta Loretz, Yanyan Li, Heinz E. Moser, Tilmann Weber, Marcus Miethke, Silke Alt, Stefano Sabatini, Wolfgang Wohlleben, Peter Hammann, Stefano Donadio, Andriy Luzhetskyy, Myriam Seemann, Rolf Müller, Hrvoje Petković, Institut de Chimie de Strasbourg, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Helmholtz-Zentrum für Infektionsforschung GmbH (HZI), Universität des Saarlandes [Saarbrücken], German Centre for Infection Research (DZIF), University of Parma = Università degli studi di Parma [Parme, Italie], Technical University of Denmark [Lyngby] (DTU), Justus-Liebig-Universität Gießen (JLU), Chimie biologique épigénétique - Epigenetic Chemical Biology (EpiCBio), Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Ecologie et Evolution de la Résistance aux Antibiotiques / Ecology and Evolution of Antibiotics Resistance (EERA), Institut Pasteur [Paris]-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Dynamique des Génomes et Adaptation Microbienne (DynAMic), Université de Lorraine (UL)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Goethe-Universität Frankfurt am Main, Max Planck Institute for Terrestrial Microbiology, Max-Planck-Gesellschaft, Universidade de Lisboa (ULISBOA), Molécules de Communication et Adaptation des Micro-organismes (MCAM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Wageningen University and Research [Wageningen] (WUR), Institut de Biologie Intégrative de la Cellule (I2BC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Fundación MEDINA, John Innes Centre [Norwich], Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), University of Manchester [Manchester], Università degli Studi di Perugia (UNIPG), University of Tübingen, Jacobs University [Bremen], University Hospital Bonn, Biophys [Usk, UK], University of Bristol [Bristol], Recursion [Salt Lake City, UT], HiberCell [New York], Uppsala Universitet [Uppsala], AMR Insights, University of Ljubljana, BEAM Alliance, Naicons, Drugs for Neglected Diseases Initiative, Global Antibiotic Research and Development Partnership [Geneva, Switzerland] (GARDP), University of Dundee, Novartis Institutes for BioMedical Research (NIBR), The project on PqsR pathoblocker development acknowledges funding through the German Center for Infection Research (DZIF, projects TTU09.908 and TTU09.916), the Helmholtz Association (Helmholtz Validation Fund) and additional contributions by the associated academic institutes (HZI and HIPS). The development of chelocardins is supported by the DZIF (TTU09.814/09.821), the Helmholtz Innovation Fund (Pre-4D), by the Slovenian Research Agency, ARRS, grant no. J4-8226, and in collaboration with AciesBio, Slovenia. The corallopyronin project is funded by the DZIF (TTU09.807/09.816, TTU09.914), the German Federal Ministry of Education and Research (BMBF), the federal state of North Rhine-Westphalia (EFRE.NRW) and EU Horizon 2020. Eriko Takano was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 720793 'TOPCAPI: Thoroughly Optimised Production Chassis for Advanced Pharmaceutical Ingredients'., European Project: 720793,H2020-EU.2.1.4.,TOPCAPI(2017), Università degli studi di Parma = University of Parma (UNIPR), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Justus-Liebig-Universität Gießen = Justus Liebig University (JLU), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Écologie et Évolution de la Résistance aux Antibiotiques / Ecology and Evolution of Antibiotics Resistance (EERA), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Université Paris-Saclay-Université Paris Cité (UPCité)-Microbiologie Intégrative et Moléculaire (UMR6047), Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Universidade de Lisboa = University of Lisbon (ULISBOA), Fundación MEDINA [Granada], Biotechnology and Biological Sciences Research Council (BBSRC), Università degli Studi di Perugia = University of Perugia (UNIPG), and Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0303 health sciences ,030306 microbiology ,Bioinformatics ,General Chemical Engineering ,[SDV]Life Sciences [q-bio] ,General Chemistry ,[CHIM.THER]Chemical Sciences/Medicinal Chemistry ,Investment (macroeconomics) ,3. Good health ,03 medical and health sciences ,Roadmap ,Risk analysis (engineering) ,13. Climate action ,Order (exchange) ,Blueprint ,ddc:570 ,Business strategy in drug development ,Bioinformatica ,Life Science ,ddc:610 ,Business ,Drug therapy ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology - Abstract
An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics. We propose both short-term and long-term solutions to overcome the most urgent limitations in the various sectors of research and funding, aiming to bridge the gap between academic, industrial and political stakeholders, and to unite interdisciplinary expertise in order to efficiently fuel the translational pipeline for the benefit of future generations., Antimicrobial resistance is an increasing threat to public health and encouraging the development of new antimicrobials is one of the most important ways to address the problem. This Roadmap article aims to bring together industrial, academic and political partners, and proposes both short-term and long-term solutions to this challenge.
- Published
- 2021
38. Non‐Carbohydrate Glycomimetics as Inhibitors of Calcium(II)‐Binding Lectins
- Author
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Annabelle Varrot, Priscila da Silva Figueiredo Celestino Gomes, Anne Imberty, Sakonwan Kuhaudomlarp, Jérémie Topin, Eike Siebs, Christoph Rademacher, Elena Shanina, Ines Joachim, Didier Rognan, Alexander Titz, Laboratoire d'Innovation Thérapeutique (LIT), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherches sur les Macromolécules Végétales (CERMAV), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Department of Biomolecular Systems [Potsdam], Max Planck Institute of Colloids and Interfaces, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut de Chimie du CNRS (INC), and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
- Subjects
Models, Molecular ,Catechols ,carbohydrates ,chemistry.chemical_element ,Microbial Sensitivity Tests ,[CHIM.THER]Chemical Sciences/Medicinal Chemistry ,Calcium ,010402 general chemistry ,medicine.disease_cause ,01 natural sciences ,Catalysis ,03 medical and health sciences ,chemistry.chemical_compound ,Glycomimetic ,medicine ,[CHIM]Chemical Sciences ,Glycosides ,Adhesins, Bacterial ,Research Articles ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,chemistry.chemical_classification ,PAINS ,0303 health sciences ,Catechol ,Molecular Structure ,biology ,010405 organic chemistry ,Pseudomonas aeruginosa ,Biofilm ,Glycoside ,Lectin ,General Medicine ,General Chemistry ,catechol ,Ligand (biochemistry) ,Anti-Bacterial Agents ,3. Good health ,0104 chemical sciences ,chemistry ,Biochemistry ,biology.protein ,glycomimetic ,lectin ,Research Article - Abstract
Because of the antimicrobial resistance crisis, lectins are considered novel drug targets. Pseudomonas aeruginosa utilizes LecA and LecB in the infection process. Inhibition of both lectins with carbohydrate‐derived molecules can reduce biofilm formation to restore antimicrobial susceptibility. Here, we focused on non‐carbohydrate inhibitors for LecA to explore new avenues for lectin inhibition. From a screening cascade we obtained one experimentally confirmed hit, a catechol, belonging to the well‐known PAINS compounds. Rigorous analyses validated electron‐deficient catechols as millimolar LecA inhibitors. The first co‐crystal structure of a non‐carbohydrate inhibitor in complex with a bacterial lectin clearly demonstrates the catechol mimicking the binding of natural glycosides with LecA. Importantly, catechol 3 is the first non‐carbohydrate lectin ligand that binds bacterial and mammalian calcium(II)‐binding lectins, giving rise to this fundamentally new class of glycomimetics., A screening yields the first non‐carbohydrate small molecules mimicking the interaction of carbohydrates in the binding sites of bacterial lectins. The catechols, known as PAINS, were carefully validated in numerous biophysical assays. A crystal structure in complex with Pseudomonas aeruginosa LecA and NMR analyses with mammalian C‐type lectin Langerin prove the catechol moiety as a general replacement motif for carbohydrates in calcium(II)‐binding lectins.
- Published
- 2021
39. Exo-β-N-acetylmuramidase NamZ of Bacillus subtilis is the founding member of a family of exo-lytic peptidoglycan hexosaminidases
- Author
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Maraike Müller, Robert Maria Kluj, Qingping Xu, Alicia Engelbrecht, Marina Borisova, Christoph Mayer, Khaled A. Selim, Alexander Titz, Tim Teufel, Katja Balbuchta, Matthew B. Calvert, and Isabel Hottmann
- Subjects
Protein family ,biology ,Firmicutes ,Mutant ,Bacillus subtilis ,biology.organism_classification ,Bacterial cell structure ,Amidase ,Hexosaminidases ,carbohydrates (lipids) ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Peptidoglycan - Abstract
Endo-β-N-acetylmuramidases, commonly known as lysozymes, are well-characterized antimicrobial enzymes that potentially lyse bacterial cells. They catalyze an endo-lytic cleavage of the peptidoglycan, the structural component of the bacterial cell wall; i.e. they hydrolyze glycosidic N-acetylmuramic acid (MurNAc)-β-1,4-N-acetylglucosamine (GlcNAc)-bonds within the heteroglycan backbone of peptidoglycan. In contrast, little is known about exo-β-N-acetylmuramidases, catalyzing an exo-lytic cleavage of β-1,4-MurNAc entities from the non-reducing ends of peptidoglycan chains. Such an enzyme was identified earlier in the bacterium Bacillus subtilis, but the corresponding gene has remained unknown so far. We identified ybbC of B. subtilis, renamed namZ, as encoding the reported exo-β-N-acetylmuramidase. A ΔnamZ mutant accumulated specific cell wall fragments and showed growth defects under starvation conditions, indicating a role of NamZ in cell wall turnover. Recombinant NamZ protein specifically hydrolyzed the artificial substrate para-nitrophenyl β-MurNAc and the peptidoglycan-derived disaccharide MurNAc-β-1,4-GlcNAc. Together with the exo-β-N-acetylglucosaminidase NagZ and the exo-muramoyl-L-alanine amidase AmiE, NamZ degraded intact peptidoglycan by sequential hydrolysis from the non-reducing ends. NamZ is a member of the DUF1343 protein family of unknown function and shows no significant sequence identity with known glycosidases. A structural model of NamZ revealed a putative active site located in a cleft within the interface of two subdomains, one of which constituting a Rossmann-fold-like domain, unusual for glycosidases. On this basis, we propose that NamZ represents the founding member of a novel family of peptidoglycan hexosaminidases, which is mainly present in the phylum Bacteroidetes and, less frequently, within Firmicutes (Bacilli, Clostridia), Actinobacteria and Gammaproteobacteria.
- Published
- 2021
40. The exo-β-N-acetylmuramidase NamZ from Bacillus subtilis is the founding member of a family of exo-lytic peptidoglycan hexosaminidases
- Author
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Alexander Titz, Qingping Xu, Marina Borisova, Alicia Engelbrecht, Isabel Hottmann, Christoph Mayer, Maraike Müller, Matthew B. Calvert, Robert Maria Kluj, Khaled A. Selim, Tim Teufel, Katja Balbuchta, and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
- Subjects
0301 basic medicine ,CAZy ,Protein family ,Glycoside Hydrolases ,peptidoglycan hydrolase ,Protein Conformation ,pNP-GlcNAc, para-nitrophenyl 2-acetamido-2-deoxy-β-d-glucopyranoside ,Bacillus subtilis ,Peptidoglycan ,cell wall recycling ,AUC, area under curve ,Crystallography, X-Ray ,Biochemistry ,N-acetylmuramidase ,Acetylglucosamine ,03 medical and health sciences ,chemistry.chemical_compound ,N-Acetylglucosamine ,Molecular Biology ,lysozyme ,BPC, base peak chromatogram ,exo-lytic glycosidase ,030102 biochemistry & molecular biology ,biology ,Chemistry ,Hydrolysis ,pNP-MurNAc, para-nitrophenyl 2-acetamido-3-O-(d-1-carboxyethyl)-2-deoxy-β-D-glucopyranoside ,Cell Biology ,GlcNAc, N-acetylglucosamine ,biology.organism_classification ,Rossmann-fold ,Hexosaminidases ,EIC, extracted ion chromatogram ,carbohydrates (lipids) ,030104 developmental biology ,N-Acetylmuramic acid ,Muramic Acids ,N-acetylglucosaminidase ,Lysozyme ,MurNAc, N-acetylmuramic acid ,Research Article ,N-acetylmuramoyl amidase - Abstract
Endo-β-N-acetylmuramidases, commonly known as lysozymes, are well-characterized antimicrobial enzymes that catalyze an endo-lytic cleavage of peptidoglycan; i.e., they hydrolyze the β-1,4-glycosidic bonds connecting N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc). In contrast, little is known about exo-β-N-acetylmuramidases, which catalyze an exo-lytic cleavage of β-1,4-MurNAc entities from the non-reducing ends of peptidoglycan chains. Such an enzyme was identified earlier in the bacterium Bacillus subtilis, but the corresponding gene has remained unknown so far. We now report that ybbC of B. subtilis, renamed namZ, encodes the reported exo-β-N-acetylmuramidase. A ΔnamZ mutant accumulated specific cell wall fragments and showed growth defects under starvation conditions, indicating a role of NamZ in cell wall turnover and recycling. Recombinant NamZ protein specifically hydrolyzed the artificial substrate para-nitrophenyl β-MurNAc and the peptidoglycan-derived disaccharide MurNAc-β-1,4-GlcNAc. Together with the exo-β-N-acetylglucosaminidase NagZ and the exo-muramoyl-l-alanine amidase AmiE, NamZ degraded intact peptidoglycan by sequential hydrolysis from the non-reducing ends. A structure model of NamZ, built on the basis of two crystal structures of putative orthologs from Bacteroides fragilis, revealed a two-domain structure including a Rossmann-fold-like domain that constitutes a unique glycosidase fold. Thus, NamZ, a member of the DUF1343 protein family of unknown function, is now classified as the founding member of a new family of glycosidases (CAZy GH171; www.cazy.org/GH171.html). NamZ-like peptidoglycan hexosaminidases are mainly present in the phylum Bacteroidetes and less frequently found in individual genomes within Firmicutes (Bacilli, Clostridia), Actinobacteria, and γ-proteobacteria.
- Published
- 2021
41. A remote secondary binding pocket promotes heteromultivalent targeting of DC-SIGN
- Author
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Robert Wawrzinek, Oliver Schwardt, Mareike Rentzsch, Hengxi Zhang, Gunnar Bachem, Carlos P. Modenutti, Maria Bräutigam, Felix F. Fuchsberger, Alexander Titz, Dirk Hauck, Gary Domeniconi, Christoph Rademacher, Oliver Seitz, Eike-Christian Wamhoff, Beat Ernst, Jessica Schulze, Jonathan Lefebre, Peter H. Seeberger, Marcelo A. Martí, Lennart Schnirch, and Mónica Guberman
- Subjects
Glycan ,Langerin ,Allosteric regulation ,Endocytic cycle ,Carbohydrates ,Cooperativity ,Receptors, Cell Surface ,Molecular Dynamics Simulation ,Ligands ,Biochemistry ,Catalysis ,Article ,Small Molecule Libraries ,Colloid and Surface Chemistry ,Antigens, CD ,Cell Line, Tumor ,Humans ,Avidity ,Lectins, C-Type ,Vesicles ,Targeting ,Binding Sites ,biology ,Chemistry ,General Chemistry ,Acquired immune system ,Chemical biology ,Cell biology ,DC-SIGN ,Molecular Docking Simulation ,Mannose-Binding Lectins ,Mannosides ,Liposomes ,biology.protein ,500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften ,Cell Adhesion Molecules ,Protein Binding - Abstract
Dendritic cells (DC) are antigen-presenting cells coordinating the interplay of the innate and the adaptive immune response. The endocytic C-type lectin receptors DC-SIGN and Langerin display expression profiles restricted to distinct DC subtypes and have emerged as prime targets for next-generation immunotherapies and anti-infectives. Using heteromultivalent liposomes copresenting mannosides bearing aromatic aglycones with natural glycan ligands, we serendipitously discovered striking cooperativity effects for DC-SIGN+ but not for Langerin+ cell lines. Mechanistic investigations combining NMR spectroscopy with molecular docking and molecular dynamics simulations led to the identification of a secondary binding pocket for the glycomimetics. This pocket, located remotely of DC-SIGN’s carbohydrate bindings site, can be leveraged by heteromultivalent avidity enhancement. We further present preliminary evidence that the aglycone allosterically activates glycan recognition and thereby contributes to DC-SIGN-specific cell targeting. Our findings have important implications for both translational and basic glycoscience, showcasing heteromultivalent targeting of DCs to improve specificity and supporting potential allosteric regulation of DC-SIGN and CLRs in general.
- Published
- 2021
42. Directing Drugs to Bugs: Antibiotic-Carbohydrate Conjugates Targeting Biofilm-Associated Lectins of
- Author
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Joscha, Meiers, Eva, Zahorska, Teresa, Röhrig, Dirk, Hauck, Stefanie, Wagner, and Alexander, Titz
- Subjects
Dose-Response Relationship, Drug ,Molecular Structure ,Carbohydrates ,biochemical phenomena, metabolism, and nutrition ,Article ,Anti-Bacterial Agents ,Structure-Activity Relationship ,HEK293 Cells ,Ciprofloxacin ,Biofilms ,Cell Line, Tumor ,Lectins ,Pseudomonas aeruginosa ,Humans - Abstract
Chronic infections by Pseudomonas aeruginosa are characterized by biofilm formation, which effectively enhances resistance toward antibiotics. Biofilm-specific antibiotic delivery could locally increase drug concentration to break antimicrobial resistance and reduce the drug’s peripheral side effects. Two extracellular P. aeruginosa lectins, LecA and LecB, are essential structural components for biofilm formation and thus render a possible anchor for biofilm-targeted drug delivery. The standard-of-care drug ciprofloxacin suffers from severe systemic side effects and was therefore chosen for this approach. We synthesized several ciprofloxacin-carbohydrate conjugates and established a structure–activity relationship. Conjugation of ciprofloxacin to lectin probes enabled biofilm accumulation in vitro, reduced the antibiotic’s cytotoxicity, but also reduced its antibiotic activity against planktonic cells due to a reduced cell permeability and on target activity. This work defines the starting point for new biofilm/lectin-targeted drugs to modulate antibiotic properties and ultimately break antimicrobial resistance.
- Published
- 2020
43. Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans
- Author
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Therese, Wohlschlager, Alexander, Titz, Markus, Künzler, and Annabelle, Varrot
- Subjects
Fungal Proteins ,Laccaria ,Models, Molecular ,Binding Sites ,Polysaccharides ,Amino Acid Motifs ,Membrane Proteins ,Crystallography, X-Ray ,Protein Structure, Secondary ,Protein Binding - Abstract
Tectonins are conserved defense proteins of innate immune systems featuring a β-propeller fold. Tectonin 2 from Laccaria bicolor, Lb-Tec2, is the first fungal representative of the tectonin superfamily that has been described. In-depth characterization revealed a specificity for O-methylated glycans and identified a unique sequence motif and binding site architecture underlying this unusual specificity. This chapter provides information on how to produce and purify recombinant Lb-Tec2, characterize its interaction with O-methylated glycans and demonstrate its biological function.
- Published
- 2020
44. Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans
- Author
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Alexander Titz, Annabelle Varrot, Therese Wohlschlager, Markus Künzler, Institute of Microbiology [Zurich], Universität Salzburg, Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Institute of Medical Microbiology [Zurich], Universität Zürich [Zürich] = University of Zurich (UZH), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Centre de Recherches sur les Macromolécules Végétales (CERMAV), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)
- Subjects
Glycan ,O-Methylated glycans ,030303 biophysics ,Nematotoxic lectin ,law.invention ,Beta-propeller ,Defense effector ,03 medical and health sciences ,Laccaria bicolor ,law ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Binding site ,030304 developmental biology ,Innate immunity ,0303 health sciences ,Innate immune system ,biology ,Chemistry ,Non-self recognition ,Lectin ,biology.organism_classification ,Biochemistry ,β-Propeller ,biology.protein ,Recombinant DNA ,Sequence motif - Abstract
International audience; Tectonins are conserved defense proteins of innate immune systems featuring a β-propeller fold. Tectonin 2 from Laccaria bicolor, Lb-Tec2, is the first fungal representative of the tectonin superfamily that has been described. In-depth characterization revealed a specificity for O-methylated glycans and identified a unique sequence motif and binding site architecture underlying this unusual specificity. This chapter provides information on how to produce and purify recombinant Lb-Tec2, characterize its interaction with O-methylated glycans and demonstrate its biological function.
- Published
- 2020
45. Ciprofloxacin-loaded lipid-core nanocapsules as mucus penetrating drug delivery system intended for the treatment of bacterial infections in cystic fibrosis
- Author
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Alexander Titz, Edilene Gadelha de Oliveira, Marc Schneider, Silvia Stanisçuaski Guterres, Paula dos Santos Chaves, Afra Torge, Ruy Carlos Ruver Beck, Stefanie Wagner, Adriana Raffin Pohlmann, and Helmholtz Institut für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany.
- Subjects
0301 basic medicine ,Staphylococcus aureus ,Cystic Fibrosis ,medicine.drug_class ,Antibiotics ,Pharmaceutical Science ,02 engineering and technology ,Biology ,medicine.disease_cause ,Cystic fibrosis ,Nanocapsules ,Microbiology ,03 medical and health sciences ,Ciprofloxacin ,medicine ,Drug Carriers ,Pseudomonas aeruginosa ,Bacterial Infections ,021001 nanoscience & nanotechnology ,medicine.disease ,Lipids ,Mucus ,030104 developmental biology ,Delayed-Action Preparations ,Drug delivery ,0210 nano-technology ,Drug carrier ,medicine.drug - Abstract
Treatment of bacterial airway infections is essential for cystic fibrosis therapy. However, effectiveness of antibacterial treatment is limited as bacteria inside the mucus are protected from antibiotics and immune response. To overcome this biological barrier, ciprofloxacin was loaded into lipid-core nanocapsules (LNC) for high mucus permeability, sustained release and antibacterial activity. Ciprofloxacin-loaded LNC with a mean size of 180nm showed a by 50% increased drug permeation through mucus. In bacterial growth assays, the drug in the LNC had similar minimum inhibitory concentrations as the free drug in P. aeruginosa and S. aureus. Interestingly, formation of biofilm-like aggregates, which were observed for S. aureus treated with free ciprofloxacin, was avoided by exposure to LNC. With the combined advantages over the non-encapsulated drug, ciprofloxacin-loaded LNC represent a promising drug delivery system with the prospect of an improved antibiotic therapy in cystic fibrosis.
- Published
- 2017
46. Efficient Two Step β‐Glycoside Synthesis from N ‐Acetyl <scp>d</scp> ‐Glucosamine: Scope and Limitations of Copper(II) Triflate‐Catalyzed Glycosylation
- Author
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Alexander Titz, Roman Sommer, Dirk Hauck, and HIPS, Helmholtz-Institute für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany.
- Subjects
N Acetyl D Glucosamine ,Glycosylation ,Copper(II) triflate ,Scope (project management) ,010405 organic chemistry ,Stereochemistry ,Two step ,Inorganic chemistry ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Glycoside synthesis ,0104 chemical sciences ,Catalysis ,carbohydrates (lipids) ,chemistry.chemical_compound ,chemistry ,N acetyl glucosamine - Abstract
β‐Linked glycosides of N‐acetyl glucosamine are widespread in nature. Their direct synthesis is hampered by the low reactivity of GlcNAc as a glycosyl donor. We report a selective and rapid copper(II) triflate‐catalyzed two‐step synthesis of β‐glycosides of GlcNAc from cheap GlcNAc as starting material without purification of intermediates. α‐Specific glycosylation can be achieved by increasing the amount of catalyst and extending reaction times.
- Published
- 2017
47. Induction of rare conformation of oligosaccharide by binding to calcium-dependent bacterial lectin: X-ray crystallography and modelling study
- Author
-
Annabelle Varrot, Sakonwan Kuhaudomlarp, Alexander Titz, Emanuele Paci, Anne Imberty, Roman Sommer, Mickaël Lelimousin, Martin Lepšík, Centre de Recherches sur les Macromolécules Végétales (CERMAV ), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), School of Chemistry [Leeds], University of Leeds, HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany., Lepsik M., Sommer R., Kuhaudomlarp S., Lelimousin M., Paci E., Varrot A., Titz A., and Imberty A.
- Subjects
Molecular dynamic ,Carbohydrate ,Glycan ,Glycoconjugate ,Stereochemistry ,Molecular Conformation ,Oligosaccharides ,Molecular Dynamics Simulation ,Molecular dynamics ,Crystallography, X-Ray ,Ligands ,010402 general chemistry ,01 natural sciences ,Quantum effect ,Epitope ,03 medical and health sciences ,Lectins ,Calcium ion ,Drug Discovery ,Theoretical chemistry ,[CHIM]Chemical Sciences ,Binding site ,Receptor ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Pharmacology ,chemistry.chemical_classification ,Glucosamine ,0303 health sciences ,Binding Sites ,biology ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Lectin ,General Medicine ,Oligosaccharide ,0104 chemical sciences ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Mutation ,Pseudomonas aeruginosa ,biology.protein ,Calcium ,N-Acetyl ,Protein Binding - Abstract
Pathogenic micro-organisms utilize protein receptors in adhesion to host tissues, a process that in some cases relies on the interaction between lectin and human glycoconjugates. Oligosaccharide epitopes are recognized through their three-dimensional structure and their flexibility is a key issue in specificity. In this paper, we analyse by X-ray crystallography the structures of the lectin LecB from two strains of Pseudomonas aeruginosa in complex with Lewis x oligosaccharide present on cell surfaces of human tissues. An unusual conformation of the glycan was observed in all binding sites with a non-canonical syn orientation of the N-acetyl group of N-acetyl-glucosamine. A PDB-wide search revealed that such an orientation occurs only in 2% of protein/carbohydrate complexes. Theoretical chemistry calculations showed that the observed conformation is unstable in solution but stabilised by the lectin. A reliable description of LecB/Lewis x complex by force field-based methods had proven as especially challenging due to the special feature of the binding site, two closely apposed Ca2+ ions which induce strong charge delocalisation. By comparing various force-field parametrisations, we design general protocols which will be useful in near future for designing carbohydrate-based ligands (glycodrugs) against other calcium-dependent protein receptors.
- Published
- 2019
48. Lectin antagonists in infection, immunity, and inflammation
- Author
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Alexander Titz, Joscha Meiers, Eike Siebs, Eva Zahorska, and HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany.
- Subjects
0301 basic medicine ,Allosteric regulation ,Chemical biology ,010402 general chemistry ,Infections ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,03 medical and health sciences ,Glycomimetic ,Lectins ,Drug Discovery ,Animals ,Humans ,Avidity ,Inflammation ,biology ,Drug discovery ,Chemistry ,Immunity ,Lectin ,Ligand (biochemistry) ,Small molecule ,0104 chemical sciences ,030104 developmental biology ,biology.protein - Abstract
Lectins are proteins found in all domains of life with a plethora of biological functions, especially in the infection process, immune response, and inflammation. Targeting these carbohydrate-binding proteins is challenged by the fact that usually low affinity interactions between lectin and glycoconjugate are observed. Nature often circumvents this process through multivalent display of ligand and lectin. Consequently, the vast majority of synthetic antagonists are multivalently displayed native carbohydrates. At the cost of disadvantageous pharmacokinetic properties and possibly a reduced selectivity for the target lectin, the molecules usually possess very high affinities to the respective lectin through ligand epitope avidity. Recent developments include the advent of glycomimetic or allosteric small molecule inhibitors for this important protein class and their use in chemical biology and drug research. This evolution has culminated in the transition of the small molecule GMI-1070 into clinical phase III. In this opinion article, an overview of the most important developments of lectin antagonists in the last two decades with a focus on the last five years is given.
- Published
- 2019
49. Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections
- Author
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Alexander Titz, Varsha R. Jumde, and Matthew B. Calvert
- Subjects
0301 basic medicine ,medicine.medical_specialty ,Antivirulence ,medicine.drug_class ,Antibiotics ,bacterial adhesins ,Review ,01 natural sciences ,World health ,lcsh:QD241-441 ,03 medical and health sciences ,Antibiotic resistance ,lcsh:Organic chemistry ,medicine ,antimicrobial resistance ,Intensive care medicine ,lcsh:Science ,pathoblockers ,bacterial toxins ,Resistance development ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,quorum sensing ,Pathogenicity ,0104 chemical sciences ,Bacterial adhesin ,030104 developmental biology ,Bacterial virulence ,lcsh:Q - Abstract
The rapid development of antimicrobial resistance is threatening mankind to such an extent that the World Health Organization expects more deaths from infections than from cancer in 2050 if current trends continue. To avoid this scenario, new classes of anti-infectives must urgently be developed. Antibiotics with new modes of action are needed, but other concepts are also currently being pursued. Targeting bacterial virulence as a means of blocking pathogenicity is a promising new strategy for disarming pathogens. Furthermore, it is believed that this new approach is less susceptible towards resistance development. In this review, recent examples of anti-infective compounds acting on several types of bacterial targets, e.g., adhesins, toxins and bacterial communication, are described.
- Published
- 2018
50. Novel Strategies for the Treatment of Pseudomonas aeruginosa Infections
- Author
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Martin Empting, Stefan Hinsberger, Roman Sommer, Cenbin Lu, Rolf W. Hartmann, Stefanie Wagner, and Alexander Titz
- Subjects
Models, Molecular ,0301 basic medicine ,medicine.drug_class ,030106 microbiology ,Antibiotics ,Biology ,medicine.disease_cause ,Cystic fibrosis ,Microbiology ,03 medical and health sciences ,Pseudomonas aeruginosa Infections ,Drug Discovery ,medicine ,Animals ,Humans ,Pseudomonas Infections ,Molecular Targeted Therapy ,Mode of action ,Pathogen ,Cross-resistance ,Pseudomonas aeruginosa ,Biofilm ,Quorum Sensing ,medicine.disease ,Anti-Bacterial Agents ,Biofilms ,Molecular Medicine - Abstract
Infections with Pseudomonas aeruginosa have become a concerning threat in hospital-acquired infections and for cystic fibrosis patients. The major problem leading to high mortality lies in the appearance of drug-resistant strains. Therefore, a vast number of approaches to develop novel anti-infectives is currently pursued. These diverse strategies span from killing (new antibiotics) to disarming (antivirulence) the pathogen. Particular emphasis lies on the development of compounds that inhibit biofilms formed in chronic infections to restore susceptibility toward antibiotics. Numerous promising results are summarized in this perspective. Antibiotics with a novel mode of action will be needed to avoid cross resistance against currently used therapeutic agents. Importantly, antivirulence drugs are expected to yield a significantly reduced rate of resistance development. Most developments are still far from the application. It can however be expected that combination therapies, also containing antivirulence agents, will pave the way toward novel treatment options against P. aeruginosa.
- Published
- 2016
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