45 results on '"Alexander Titz"'
Search Results
2. 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
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- 2022
3. 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
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- 2023
4. 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
5. Neutralisation der Auswirkungen des Virulenzfaktors LecA aus Pseudomonas aeruginosa auf Humanzellen durch neue glykomimetische Inhibitoren
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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
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General Medicine - Published
- 2023
6. 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.
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- 2021
7. Pineapple Lectin AcmJRL Binds SARS-CoV-2 Spike Protein in a Carbohydrate-Dependent Fashion
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Sebastian Adam, Rolf Müller, Jan Dastbaz, Joscha Meiers, Alexander Titz, Peter Gross, Susanne Kirsch, Sari Rasheed, and Peter Meiser
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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
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- 2022
8. Discovery of
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Patrycja, Mała, Eike, Siebs, Joscha, Meiers, Katharina, Rox, Annabelle, Varrot, Anne, Imberty, and Alexander, Titz
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Mice ,Sulfonamides ,Lectins ,Biofilms ,Pseudomonas aeruginosa ,Thiourea ,Humans ,Animals ,Ligands ,Amides ,Anti-Bacterial Agents - Abstract
The Gram-negative pathogen
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- 2022
9. Lectin-Targeted Prodrugs Activated by
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Joscha, Meiers, Katharina, Rox, and Alexander, Titz
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Virulence Factors ,Lectins ,Biofilms ,Pseudomonas aeruginosa ,Humans ,Prodrugs ,Pseudomonas Infections ,Anti-Bacterial Agents ,Fluoroquinolones - Abstract
Chronic
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- 2022
10. Directing Drugs to Bugs: Antibiotic-Carbohydrate Conjugates Targeting Biofilm-Associated Lectins of Pseudomonas aeruginosa
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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.
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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.
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- 2020
11. Protein-observed 19F NMR of LecA from Pseudomonas aeruginosa
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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.
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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.
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- 2020
12. 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
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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.
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- 2022
13. Targeting extracellular lectins of
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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.
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- 2022
14. Concept trade-off and detailed design of a 1U NanoSat 100W deployable solar array and it’s in-orbit demonstration preparation
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Thomas Sinn, Thomas Lund, Joram Gruber, Alexander Titz, and Ambre Raharijaona
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- 2022
15. Correction: Concept trade-off and detailed design of a 1U NanoSat 100W deployable solar array and it’s in-orbit demonstration preparation
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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
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- 2022
16. Targeting undruggable carbohydrate recognition sites through focused fragment library design
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Elena Shanina, Sakonwan Kuhaudomlarp, Eike Siebs, Felix F. Fuchsberger, Maxime Denis, Priscila da Silva Figueiredo Celestino Gomes, Mads H. Clausen, Peter H. Seeberger, Didier Rognan, Alexander Titz, Anne Imberty, and Christoph Rademacher
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Chemical libraries ,Materials Chemistry ,Screening ,Environmental Chemistry ,Carbohydrate-protein interactions ,General Chemistry ,500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften ,Biochemistry - Abstract
Carbohydrate-protein interactions are key for cell-cell and host-pathogen recognition, but their hydrophilic nature makes the development of drug-like inhibitors a challenge. Here, screening of fragment libraries identifies metal-binding pharmacophores as novel scaffolds for the inhibition of Ca2+-dependent carbohydrate-protein interactions. Carbohydrate-protein interactions are key for cell-cell and host-pathogen recognition and thus, emerged as viable therapeutic targets. However, their hydrophilic nature poses major limitations to the conventional development of drug-like inhibitors. To address this shortcoming, four fragment libraries were screened to identify metal-binding pharmacophores (MBPs) as novel scaffolds for inhibition of Ca2+-dependent carbohydrate-protein interactions. Here, we show the effect of MBPs on the clinically relevant lectins DC-SIGN, Langerin, LecA and LecB. Detailed structural and biochemical investigations revealed the specificity of MBPs for different Ca2+-dependent lectins. Exploring the structure-activity relationships of several fragments uncovered the functional groups in the MBPs suitable for modification to further improve lectin binding and selectivity. Selected inhibitors bound efficiently to DC-SIGN-expressing cells. Altogether, the discovery of MBPs as a promising class of Ca2+-dependent lectin inhibitors creates a foundation for fragment-based ligand design for future drug discovery campaigns.
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- 2022
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17. NamZ1 and NamZ2 from the oral pathogen Tannerella forsythia are peptidoglycan processing exo-β-N-acetylmuramidases with distinct substrate specificity
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Andrew L. Lovering, Alexander Titz, Katja Balbuchta, Christoph Mayer, and Marina Borisova
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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.
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- 2021
18. Targeting the Central Pocket of the Pseudomonas aeruginosa Lectin LecA
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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)
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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.
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- 2021
19. Towards the sustainable discovery and development of new antibiotics
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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)
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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
20. 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
21. 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
22. 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
23. Expression, Purification, and Functional Characterization of Tectonin 2 from Laccaria bicolor: A Six-Bladed Beta-Propeller Lectin Specific for O-Methylated Glycans
- Author
-
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
24. 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
25. 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
26. 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
27. 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
28. Novel Strategies for the Treatment of Pseudomonas aeruginosa Infections
- Author
-
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
29. An efficient synthesis of 1,6-anhydro- N -acetylmuramic acid from N -acetylglucosamine
- Author
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Christoph Mayer, Matthew B. Calvert, Alexander Titz, Helmholtz Institut für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany., and HIPS, Helmholtz-Institut für pharmazeutische Forschung Saarland, Universitätscampus 8.1, 66123 Saarbrücken, Germany.
- Subjects
Future studies ,Letter ,antibiotic resistance ,Stereochemistry ,Carbohydrate synthesis ,010402 general chemistry ,01 natural sciences ,Bacterial cell structure ,lcsh:QD241-441 ,chemistry.chemical_compound ,lcsh:Organic chemistry ,N-Acetylglucosamine ,lcsh:Science ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,bacterial cell wall recycling ,Anhydro-N-acetylmuramic acid ,0104 chemical sciences ,carbohydrate synthesis ,N-Acetylmuramic acid ,lcsh:Q ,anhydrosugars ,N-acetylmuramic acid - 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.
- Published
- 2017
30. Photoswitchable Janus glycodendrimer micelles as multivalent inhibitors of LecA and LecB from Pseudomonas aeruginosa
- Author
-
Yingxue Hu, Rico F. Tabor, Alexander Titz, Brendan L. Wilkinson, Ghamdan Beshr, and Christopher J. Garvey
- Subjects
Dendrimers ,Photoisomerization ,010402 general chemistry ,01 natural sciences ,Micelle ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Dynamic light scattering ,Dendrimer ,Lectins ,Amphiphile ,Scattering, Small Angle ,Organic chemistry ,Janus ,Physical and Theoretical Chemistry ,Adhesins, Bacterial ,Micelles ,010405 organic chemistry ,Surfaces and Interfaces ,General Medicine ,Small-angle neutron scattering ,Dynamic Light Scattering ,0104 chemical sciences ,3. Good health ,Azobenzene ,chemistry ,Pseudomonas aeruginosa ,Biophysics ,Azo Compounds ,Hydrophobic and Hydrophilic Interactions ,Biotechnology - Abstract
The first example of the self-assembly and lectin binding properties of photoswitchable glycodendrimer micelles is reported. Light-addressable micelles were assembled from a library of 12 amphiphilic Janus glycodendrimers composed of variable carbohydrate head groups and hydrophobic tail groups linked to an azobenzene core. Spontaneous association in water gave cylindrical micelles with uniform size distribution as determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). Trans-cis photoisomerization of the azobenzene dendrimer core was used to probe the self-assembly behaviour and lectin binding properties of cylindrical micelles, revealing moderate-to-potent inhibition of lectins LecA and LecB from Pseudomonas aeruginosa.
- Published
- 2017
31. Amphiphilic Cationic β3R3-Peptides: Membrane Active Peptidomimetics and Their Potential as Antimicrobial Agents
- Author
-
Janos Keller, Stefanie Wagner, Laura Hartmann, Nahid Azzouz, Simone Mosca, Alexander Titz, Peter H. Seeberger, and Gerald Brezesinski
- Subjects
Staphylococcus aureus ,Polymers and Plastics ,Peptidomimetic ,Stereochemistry ,Antimicrobial peptides ,Bioengineering ,Microbial Sensitivity Tests ,Oligomer ,Biomaterials ,Structure-Activity Relationship ,Surface-Active Agents ,chemistry.chemical_compound ,Cations ,Amphiphile ,Escherichia coli ,Materials Chemistry ,Structure–activity relationship ,Dose-Response Relationship, Drug ,Molecular Structure ,Chemistry ,Cell Membrane ,Cationic polymerization ,Antimicrobial ,Anti-Bacterial Agents ,Micrococcus luteus ,Membrane ,Pseudomonas aeruginosa ,Peptidomimetics ,Peptides - Abstract
We introduce a novel class of membrane active peptidomimetics, the amphiphilic cationic β(3R3)-peptides, and evaluate their potential as antimicrobial agents. The design criteria, the building block and oligomer synthesis as well as a detailed structure-activity relationship (SAR) study are reported. Specifically, infrared reflection absorption spectroscopy (IRRAS) was employed to investigate structural features of amphiphilic cationic β(3R3)-peptide sequences at the hydrophobic/hydrophilic air/liquid interface. Furthermore, Langmuir monolayers of anionic and zwitterionic phospholipids have been used to model the interactions of amphiphilic cationic β(3R3)-peptides with prokaryotic and eukaryotic cellular membranes in order to predict their membrane selectivity and elucidate their mechanism of action. Lastly, antimicrobial activity was tested against Gram-positive M. luteus and S. aureus as well as against Gram-negative E. coli and P. aeruginosa bacteria along with testing hemolytic activity and cytotoxicity. We found that amphiphilic cationic β(3R3)-peptide sequences combine high and selective antimicrobial activity with exceptionally low cytotoxicity in comparison to values reported in the literature. Overall, this study provides further insights into the SAR of antimicrobial peptides and peptidomimetics and indicates that amphiphilic cationic β(3R3)-peptides are strong candidates for further development as antimicrobial agents with high therapeutic index.
- Published
- 2014
32. Development and optimization of a competitive binding assay for the galactophilic low affinity lectin LecA from Pseudomonas aeruginosa
- Author
-
Alexander Titz, Sebastian Rikker, Daniela Ponader, Roman Sommer, Sophia Boden, Laura Hartmann, Dirk Hauck, and Ines Joachim
- Subjects
medicine.drug_class ,Antibiotics ,Fluorescence Polarization ,010402 general chemistry ,medicine.disease_cause ,Ligands ,01 natural sciences ,Biochemistry ,Binding, Competitive ,Virulence factor ,Microbiology ,Structure-Activity Relationship ,medicine ,Structure–activity relationship ,Humans ,Physical and Theoretical Chemistry ,Adhesins, Bacterial ,Pathogen ,Fluorescent Dyes ,biology ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Pseudomonas aeruginosa ,Organic Chemistry ,Biofilm ,Lectin ,Galactose ,biology.organism_classification ,0104 chemical sciences ,biology.protein ,Blood Group Antigens ,Bacteria - Abstract
Infections with the Gram-negative bacterium Pseudomonas aeruginosa result in a high mortality among immunocompromised patients and those with cystic fibrosis. The pathogen can switch from planktonic life to biofilms, and thereby shields itself against antibiotic treatment and host immune defense to establish chronic infections. The bacterial protein LecA, a C-type lectin, is a virulence factor and an integral component for biofilm formation. Inhibition of LecA with its carbohydrate ligands results in reduced biofilm mass, a potential Achilles heel for treatment. Here, we report the development and optimization of a fluorescence polarization-based competitive binding assay with LecA for application in screening of potential inhibitors. As a consequence of the low affinity of D-galactose for LecA, the fluorescent ligand was optimized to reduce protein consumption in the assay. The assay was validated using a set of known inhibitors of LecA and IC50 values in good agreement with the known Kd values were obtained. Finally, we employed the optimized assay to screen sets of synthetic thio-galactosides and natural blood group antigens and report their structure–activity relationship. In addition, we evaluated a multivalent fluorescent assay probe for LecA and report its applicability in an inhibition assay.
- Published
- 2016
33. Conformational Constraints: Nature Does It Best with Sialyl Lewisx
- Author
-
Alessandro Dondoni, George Papandreou, Martin Smieško, Alexander Titz, Beat Ernst, Brian Cutting, and Alberto Marra
- Subjects
chemistry.chemical_classification ,Glycoproteins ,Conformational analysis ,Carbohydrates ,Stacking interactions ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Inflammatory cascade ,Tetrasaccharide ,Physical and Theoretical Chemistry ,Glycoprotein ,Selectin ,Methyl group - Abstract
Selectins play a key role in the inflammatory cascade. The interaction with their physiological ligands containing the tetrasaccharide sialyl Lewisx (sLex) leads to the recruitment of leukocytes from the vascular system to the site of injury. To facilitate the interaction under the shear stress conditions present in the blood vessel, the conformation of sLex is stabilized via lipophilic inter-residual contacts. sLex and two analogs were synthesized and evaluated for selectin binding, average conformation, and conformational dynamics. We could show that the methyl group in L-fucose is optimally suited to stabilize the sLex core through an interaction with the β-face of D-galactose and thus enables binding to the selectins under shear stress conditions.
- Published
- 2012
34. FORMULA-STUDENT-RENNWAGEN MIT SELEKTIVER ZYLINDERABSCHALTUNG
- Author
-
Dominik Thyroff, Alexander Titz, Moritz Schumacher, and Fabian Liebst
- Subjects
Engineering ,business.industry ,General Medicine ,business ,Manufacturing engineering - Published
- 2011
35. Abstract 3752: Preclinical pharmacology of MP0310: A 4-1BB/FAP bispecific DARPin drug candidate promoting tumor-restricted T-cell costimulation
- Author
-
Alexander Link, Mirela Matzner, Guy Lemaillet, Ralph Bessey, Elmar vom Baur, Christian Reichen, Julia Hepp, Patricia Schildknecht, Keith M. Dawson, Hong Ji, Alexander Titz, Joanna Taylor, Dan Snell, Laurent Juglair, Michael T. Stumpp, Ivana Tosevski, Victor Levitsky, Joerg Herbst, Christof Zitt, and Andreas Harstrick
- Subjects
030203 arthritis & rheumatology ,Cancer Research ,biology ,business.industry ,medicine.drug_class ,T cell ,CD137 ,Monoclonal antibody ,Memory T cell proliferation ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,Oncology ,Fibroblast activation protein, alpha ,DARPin ,030220 oncology & carcinogenesis ,biology.protein ,Cancer research ,Medicine ,Cytotoxic T cell ,Antibody ,business - Abstract
Agonistic antibodies against the T cell costimulatory receptor 4-1BB (CD137) have proved to be very efficacious anti-tumor agents in preclinical animal models. However, clinical development of 4-1BB agonistic antibodies has met with limited success thus far. Anti-4-1BB monoclonal antibodies have either been reported to cause significant dose-limiting hepatotoxicity or demonstrated limited efficacy as single agent therapeutics. Here we describe the generation of a tumor-targeted 4-1BB agonist aimed at inducing more effective triggering of 4-1BB without associated systemic toxicity. Tumor targeting is achieved via fibroblast activation protein (FAP) which is abundantly expressed by cancer associated fibroblasts present in many solid tumors. Drug candidate MP0310 comprises DARPin domains binding to 4-1BB and FAP and is devoid of an antibody Fc domain. Compared to first generation monoclonal antibodies targeting 4-1BB, MP0310 shows high potency in vitro and less systemic activation in vivo. In vitro reporter and T cell assays indicate that MP0310 is a potent T cell co-stimulator whose activity is restricted to the presence of FAP-expressing cells. In humanized mouse xenograft studies, FAP-targeted 4-1BB activation induced potent co-stimulation of CD8 T cells leading to tumor growth inhibition. On the other hand, the DARPin molecule did not induce effects associated with strong systemic activation such as hepatotoxicity or exacerbation of graft versus host disease observed in such models, unlike the first generation FcγR-dependent 4-1BB antibodies. In addition, no systemic activation of T cell proliferation was observed in the absence of FAP-positive tumors. In healthy cynomolgus monkeys, administration of MP0310 did not induce systemic stimulation of memory T cell proliferation in contrast to an anti-4-1BB antibody despite MP0310 being fully cross-reactive to cyno 4-1BB and binding effectively to cyno FAP. Therefore, we conclude that the tumor-restricted co-stimulation of 4-1BB may prevent toxicities caused by systemic 4-1BB activation and provide a safe and effective way to boost anti-tumor T cell responses. This could allow more effective dosing and better combination therapies with checkpoint inhibitors and other immune stimulating drugs. MP0310 is in preparation to enter clinical development. Citation Format: Alexander Link, Julia Hepp, Christian Reichen, Patricia Schildknecht, Ivana Tosevski, Joanna Taylor, Laurent Juglair, Alexander Titz, Mirela Matzner, Ralph Bessey, Christof Zitt, Guy Lemaillet, Joerg Herbst, Keith M. Dawson, Hong Ji, Victor Levitsky, Dan Snell, Michael T. Stumpp, Andreas Harstrick, Elmar vom Baur. Preclinical pharmacology of MP0310: A 4-1BB/FAP bispecific DARPin drug candidate promoting tumor-restricted T-cell costimulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3752.
- Published
- 2018
36. Molecular Basis for Galactosylation of Core Fucose Residues in Invertebrates
- Author
-
Alex Butschi, Markus Aebi, Ebrahim Razzazi-Fazeli, Markus Künzler, Alexander Titz, Michael O. Hengartner, Bernard Henrissat, Yao-Yun Fan, Iain B. H. Wilson, and Thierry Hennet
- Subjects
Galactosyltransferase ,Glycan ,biology ,Cell Biology ,biology.organism_classification ,Biochemistry ,Fucose ,Coprinopsis cinerea ,chemistry.chemical_compound ,chemistry ,Glycosyltransferase ,biology.protein ,Molecular Biology ,Gene ,Caenorhabditis elegans ,Galectin - Abstract
Galectin CGL2 from the ink cap mushroom Coprinopsis cinerea displays toxicity toward the model nematode Caenorhabditis elegans. A mutation in a putative glycosyltransferase-encoding gene resulted in a CGL2-resistant C. elegans strain characterized by N-glycans lacking the β1,4-galactoside linked to the α1,6-linked core fucose. Expression of the corresponding GALT-1 protein in insect cells was used to demonstrate a manganese-dependent galactosyltransferase activity. In vitro, the GALT-1 enzyme showed strong selectivity for acceptors with α1,6-linked N-glycan core fucosides and required Golgi- dependent modifications on the oligosaccharide antennae for optimal synthesis of the Gal-β1,4-fucose structure. Phylogenetic analysis of the GALT-1 protein sequence identified a novel glycosyltransferase family (GT92) with members widespread among eukarya but absent in mammals.
- Published
- 2009
37. Bisecting Galactose as a Feature of N-Glycans of Wild-type and Mutant Caenorhabditis elegans
- Author
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Alexander Titz, Iain B. H. Wilson, Shi Yan, Niclas G. Karlsson, Chunsheng Jin, Katharina Paschinger, Lothar Brecker, Martin Dragosits, and Verena Jantsch
- Subjects
Glycan ,Proteome ,Proton Magnetic Resonance Spectroscopy ,Mutant ,Biochemistry ,Methylation ,Fucose ,Analytical Chemistry ,chemistry.chemical_compound ,Gene Knockout Techniques ,Isomerism ,Polysaccharides ,Tandem Mass Spectrometry ,Mannosidases ,Animals ,Protein Isoforms ,Caenorhabditis elegans ,Molecular Biology ,Gene ,Fucosylation ,Chromatography, High Pressure Liquid ,Glycoproteins ,Chromatography, Reverse-Phase ,biology ,Research ,Wild type ,Galactose ,biology.organism_classification ,Fucosyltransferases ,chemistry ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Mutation ,biology.protein - Abstract
The N-glycosylation of the model nematode Caenorhabditis elegans has proven to be highly variable and rather complex; it is an example to contradict the existing impression that “simple” organisms possess also a rather simple glycomic capacity. In previous studies in a number of laboratories, N-glycans with up to four fucose residues have been detected. However, although the linkage of three fucose residues to the N,N′-diacetylchitobiosyl core has been proven by structural and enzymatic analyses, the nature of the fourth fucose has remained uncertain. By constructing a triple mutant with deletions in the three genes responsible for core fucosylation (fut-1, fut-6 and fut-8), we have produced a nematode strain lacking products of these enzymes, but still retaining maximally one fucose residue on its N-glycans. Using mass spectrometry and HPLC in conjunction with chemical and enzymatic treatments as well as NMR, we examined a set of α-mannosidase-resistant N-glycans. Within this glycomic subpool, we can reveal that the core β-mannose can be trisubstituted and so carries not only the ubiquitous α1,3- and α1,6-mannose residues, but also a “bisecting” β-galactose, which is substoichiometrically modified with fucose or methylfucose. In addition, the α1,3-mannose can also be α-galactosylated. Our data, showing the presence of novel N-glycan modifications, will enable more targeted studies to understand the biological functions and interactions of nematode glycans.
- Published
- 2015
38. Synthesis of mannoheptose derivatives and their evaluation as inhibitors of the lectin LecB from the opportunistic pathogen Pseudomonas aeruginosa
- Author
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Dirk Hauck, Roman Sommer, Inigo Göttker-Schnetmann, Anna Hofmann, Alexander Titz, Julia Stifel, and hemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany.
- Subjects
Stereochemistry ,medicine.disease_cause ,Crystallography, X-Ray ,Ligands ,Methylmannosides ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Amide ,Lectins ,Nitriles ,medicine ,Monosaccharide ,Amines ,chemistry.chemical_classification ,biology ,Pseudomonas aeruginosa ,Organic Chemistry ,Biofilm ,Diastereomer ,Lectin ,General Medicine ,biology.organism_classification ,Heptoses ,Sulfonamide ,chemistry ,biology.protein ,Bacteria ,Protein Binding - Abstract
Biofilm formation and chronic infections with Pseudomonas aeruginosa depend on lectins produced by the bacterium. The bacterial C-type lectin LecB binds to the two monosaccharides l-fucose and d-mannose and conjugates thereof. Previously, d-mannose derivatives with amide and sulfonamide substituents at C6 were reported as potent inhibitors of the bacterial lectin LecB and LecB-mediated bacterial surface adhesion. Because d-mannose establishes a hydrogen bond via its 6-OH group with Ser23 of LecB in the crystal structure and may be beneficial for binding affinity, we extended d-mannose and synthesized mannoheptoses bearing the free 6-OH group as well as amido and sulfonamido-substituents at C7. Two series of diastereomeric mannoheptoses were synthesized and the stereochemistry was determined by X-ray crystallography. The potency of the mannoheptoses as LecB inhibitors was assessed in a competitive binding assay. The data reveal a diastereoselectivity of LecB for (6S)-mannoheptose derivatives with increased activity over methyl α-d-mannoside.
- Published
- 2014
39. Copper dipicolinates as peptidomimetic ligands for the Src SH2 domain
- Author
-
Guofeng Ye, Keykavous Parang, Boris Schmidt, Alexander Titz, and Jan Jiricek
- Subjects
Magnetic Resonance Spectroscopy ,Peptidomimetic ,Stereochemistry ,Clinical Biochemistry ,Pharmaceutical Science ,Peptide ,Ligands ,SH2 domain ,Biochemistry ,Protein–protein interaction ,src Homology Domains ,chemistry.chemical_compound ,Drug Discovery ,Chelation ,Picolinic Acids ,Molecular Biology ,chemistry.chemical_classification ,Ligand ,Molecular Mimicry ,Organic Chemistry ,Electron Spin Resonance Spectroscopy ,Dipicolinic acid ,chemistry ,Molecular Medicine ,Peptides ,Copper ,Proto-oncogene tyrosine-protein kinase Src - Abstract
The introduction of copper chelates into peptide mimetics creates the Src SH2 binding ligands and paramagnetic complexes suitable for EPR studies of peptide protein interactions. The dipicolinic acid was attached to SH2 domain targeting fragments by two different linkers.
- Published
- 2004
40. Comparison of an FAP-targeted, CD137 activating DARPin drug candidate with a non-targeted, CD137 activating antibody in a human PBMC transplanted HT-29 mouse tumor model
- Author
-
Ralph Bessey, Michael T. Stumpp, Alexander Titz, Victor Levitsky, Clara Metz, Ulrike Fiedler, Ivana Tosevski, Simon Fontaine, Alexander Link, Keith M. Dawson, Christof Zitt, Dan Snell, Christian Reichen, Daniel Steiner, Patricia Schildknecht, Julia Hepp, Zita Arany, Laurent Juglair, and Yvonne Kaufmann
- Subjects
Cancer Research ,Non targeted ,biology ,Drug candidate ,business.industry ,medicine.drug_class ,CD137 ,Monoclonal antibody ,Peripheral blood mononuclear cell ,Molecular biology ,Oncology ,DARPin ,Cancer research ,biology.protein ,Medicine ,Mouse tumor ,Antibody ,business - Abstract
e14626 Background: Urelumab (BMS-663513) is a humanized monoclonal antibody binding to CD137 which, upon Fc-clustering, leads to activation of T-cells. Urelumab is currently in Phase 2 clinical development and has been reported to cause significant hepatotoxicities (around 15% Grade ≥2 ALT and AST elevation) when given as infusion every 3 weeks at doses ≥0.3 mg/kg. Currently ongoing clinical trials report decreased systemic toxicity but limited efficacy at lower doses of urelumab. We hypothesized that more effective triggering of CD137 without associated systemic toxicity may be achieved by targeting a CD137 agonistic engager without Fc to fibroblast activation protein (FAP) which is abundantly expressed in the stroma of many solid tumors. To achieve this, a targeted molecule belonging to the DARPin family of binding proteins was composed of one FAP- and two CD137-binding domains in a “beads on a string” format and tested in a mouse model with human PBMCs. Methods: Human PBMCs were used to reconstitute the immune system in NOG mice implanted subcutaneously with HT-29 human colon cancer cells. Mice were monitored for survival, body weight, and tumor size during the treatment phase of two weeks. Results: None of the mice in the control group died and no significant body weight loss was observed. Six of ten (60%) mice in the CD137 antibody group showed strong signs of graft vs. host disease and either died or reached the termination criterion of ≥20% body weight loss and were sacrificed. One of 30 (3%) mice died in the DARPin drug candidate groups but none of the animals showed body weight loss of ≥20% (p < 0.001, Log-rank test). Tumor growth inhibition was comparable for all treatment groups (around 20-30% at Day 18, p < 0.05 vs. control, Mann Whitney Test). Conclusions: This study confirms the hypothesis that systemic toxicities caused by the urelumab mode of action can be circumvented by FAP-targeting of a CD137 agonistic DARPin drug candidate while achieving comparable tumor growth inhibition. Consequently, higher clinical doses of tumor stroma-targeted agonistic DARPin drug candidates might be possible, and may result in stronger tumor growth inhibition.
- Published
- 2017
41. Methylated glycans as conserved targets of animal and fungal innate defense
- Author
-
Markus Aebi, Grigorij Sutov, Dirk Hauck, Robert Gauss, Alex Butschi, Stuart M. Haslam, Anne Dell, Stefanie S. Schmieder, Therese Wohlschlager, Paola Grassi, Markus Künzler, Martin Knobel, Alexander Titz, Michael O. Hengartner, University of Zurich, and Künzler, Markus
- Subjects
1000 Multidisciplinary ,Glycan ,Multidisciplinary ,Innate immune system ,biology ,Protein family ,Membrane transport protein ,Effector ,Lectin ,biology.organism_classification ,10124 Institute of Molecular Life Sciences ,Immunity, Innate ,Fucose ,chemistry.chemical_compound ,PNAS Plus ,chemistry ,Biochemistry ,Polysaccharides ,biology.protein ,570 Life sciences ,Animals ,Agaricales ,Caenorhabditis elegans - Abstract
Effector proteins of innate immune systems recognize specific non-self epitopes. Tectonins are a family of β-propeller lectins conserved from bacteria to mammals that have been shown to bind bacterial lipopolysaccharide (LPS). We present experimental evidence that two Tectonins of fungal and animal origin have a specificity for O-methylated glycans. We show that Tectonin 2 of the mushroom Laccaria bicolor (Lb-Tec2) agglutinates Gram-negative bacteria and exerts toxicity toward the model nematode Caenorhabditis elegans, suggesting a role in fungal defense against bacteria and nematodes. Biochemical and genetic analysis of these interactions revealed that both bacterial agglutination and nematotoxicity of Lb-Tec2 depend on the recognition of methylated glycans, namely O-methylated mannose and fucose residues, as part of bacterial LPS and nematode cell-surface glycans. In addition, a C. elegans gene, termed samt-1, coding for a candidate membrane transport protein for the presumptive donor substrate of glycan methylation, S-adenosyl-methionine, from the cytoplasm to the Golgi was identified. Intriguingly, limulus lectin L6, a structurally related antibacterial protein of the Japanese horseshoe crab Tachypleus tridentatus, showed properties identical to the mushroom lectin. These results suggest that O-methylated glycans constitute a conserved target of the fungal and animal innate immune system. The broad phylogenetic distribution of O-methylated glycans increases the spectrum of potential antagonists recognized by Tectonins, rendering this conserved protein family a universal defense armor.
- Published
- 2014
42. Carbohydrate-Based Anti-Virulence Compounds Against Chronic Pseudomonas aeruginosa Infections with a Focus on Small Molecules
- Author
-
Alexander Titz
- Subjects
biology ,Pseudomonas aeruginosa ,Chemistry ,Pseudomonas ,Biofilm ,Virulence ,medicine.disease_cause ,biology.organism_classification ,Small molecule ,Bacterial cell structure ,Microbiology ,medicine ,Bacteria ,Intracellular - Abstract
The Gram-negative bacterium Pseudomonas aeruginosa can establish life-threatening chronic infections through biofilm formation. The two bacterial lectins LecA and LecB play important roles in the formation of these biofilms and the inhibition of the lectins with carbohydrate-based ligands was shown to disrupt biofilms. These effects provide a novel therapeutic option against infections caused by P. aeruginosa. In addition to the urgent need for novel therapeutics against Pseudomonas infections, two major advantages arise from these lectins as targets for therapy: (1) the extracellular localization and site of activity of LecA and LecB circumvent the bacterial cell envelope as a particularly impermeable barrier of Gram-negative pathogens, which must be overcome by drugs against intracellular targets, and (2) the lectins are targets of the so-called anti-virulence therapy and therefore a reduced appearance of resistances towards lectin-directed drugs can be anticipated. In this review, the recent development of carbohydrate-based inhibitors against both lectins is summarized with a main focus on small molecules.
- Published
- 2014
43. Probing the carbohydrate recognition domain of E-selectin: the importance of the acid orientation in sLex mimetics
- Author
-
Martin Smieško, Alexander Titz, Oliver Schwardt, John L. Magnani, Beat Ernst, Zorana Radic, and John T. Patton
- Subjects
Models, Molecular ,Stereochemistry ,Carboxylic acid ,Clinical Biochemistry ,Pharmaceutical Science ,Oligosaccharides ,Ligands ,Biochemistry ,chemistry.chemical_compound ,Biomimetics ,Drug Discovery ,E-selectin ,Neuraminic acid ,Serine ,Tetrasaccharide ,Humans ,Sialyl Lewis X Antigen ,Molecular Biology ,chemistry.chemical_classification ,Binding Sites ,biology ,Chemistry ,Cell adhesion molecule ,Organic Chemistry ,Sialyl-Lewis X ,biology.protein ,Molecular Medicine ,Pharmacophore ,E-Selectin ,Selectin ,Protein Binding - Abstract
The selectin–leukocyte interaction is the initial event in the early inflammatory cascade. This interplay proceeds via the terminal tetrasaccharide sialyl Lewis x (sLe x ), present on physiological selectin ligands and E- and P-selectins located on the endothelial surface. Blocking this process is regarded as a promising therapeutic approach for inflammatory diseases where excessive leukocyte efflux is responsible for tissue damage. Selectin antagonists are generally based on sLe x as lead structure, containing the essential pharmacophores pre-oriented in the bioactive conformation. In this work, we describe a set of competitive sLe x mimetics possessing the carboxylic acid pharmacophore equipped with additional hydrophobic substituents as neuraminic acid (Neu5Ac) replacements. This small library of antagonists derived from Huisgen-1,3-dipolar cycloadditions allows to further probe the carbohydrate recognition domain of E-selectin.
- Published
- 2009
44. Complexation of copper(II)-Chelidamate: A multifrequency-pulsed electron paramagnetic resonance and electron nuclear double resonance analysis
- Author
-
and Alexander Titz, † Rüdiger-Albert Eichel, Klaus-Peter Dinse, Boris Schmidt, and Elvir Ramić
- Subjects
Models, Molecular ,Magnetic Resonance Spectroscopy ,Chemical Phenomena ,Pyridones ,Analytical chemistry ,Biophysics ,Molecular Conformation ,chemistry.chemical_element ,Electrons ,Ligands ,law.invention ,law ,Materials Chemistry ,Physical and Theoretical Chemistry ,Spin label ,Electron paramagnetic resonance ,Hyperfine structure ,Electron nuclear double resonance ,Models, Statistical ,Pulsed EPR ,Chemistry ,Chemistry, Physical ,Electron Spin Resonance Spectroscopy ,Dimethylformamide ,Copper ,Surfaces, Coatings and Films ,Oxygen ,Models, Chemical ,Spectrophotometry ,Quadrupole ,Solid solution - Abstract
Multifrequency electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) techniques were used to obtain structural information about the copper(II)-chelidamate complex. Well-resolved nitrogen ENDOR spectra could be recorded from solid solution samples by using selective excitation of spin packets. Evaluation of nuclear quadrupole and dipolar hyperfine interaction of the directly ligated nitrogen allowed for an identification of the bond direction to the copper ion within the eigen frame of the copper g-matrix. Invoking two-dimensional EPR techniques, additional hyperfine interaction with a "distant" nitrogen spin, identified as resulting from the solvent dimethylformamide (DMF), was observed. The experimental data are only consistent with formation of a stable pseudoplanar copper complex with single solvent ligation via its oxygen atom.
- Published
- 2006
45. Electrochemical synthesis of dimerizing and nondimerizing orthoquinone monoketals
- Author
-
Jean-Michel Léger, Isabelle Fabre, Denis Deffieux, Alexander Titz, and Stéphane Quideau
- Subjects
chemistry.chemical_classification ,Reaction mechanism ,Organic Chemistry ,Quinones ,Regioselectivity ,Stereoisomerism ,General Medicine ,Ketones ,Electrochemistry ,Combinatorial chemistry ,Quinone ,chemistry.chemical_compound ,chemistry ,Intramolecular force ,Organic chemistry ,Chemical stability ,Stereoselectivity ,Reactivity (chemistry) ,Methanol ,Bridged compounds ,Dimerization ,Oxidation-Reduction - Abstract
Anodic oxidation of appropriately substituted 2-methoxyphenols or alpha-(2-methoxyphenoxy)-2-methylpropionic acids in the presence of methanol furnishes stable orthoquinone monoketals, and thus constitutes a valuable alternative to the use of chemical oxidants that are often based on toxic metallic species. The propionic acid derivatives are initially converted into O-spirolactonic quinone bisketals that are then selectively hydrolyzed into the desired monoketal compounds. In the absence of blocking substituents, orthoquinone monoketals spontaneously undergo Diels-Alder dimerizations into tricyclododecadienedienones with extraordinary site selectivity, regioselectivity, and stereoselectivity. Suggestions are made to open up a new track for a long awaited rationalization of these controls on the basis of the intramolecular [2 + 2] reactivity of these orthoquinone monoketal-derived cyclodimers.
- Published
- 2004
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