16 results on '"Katja M, Fisch"'
Search Results
2. Antimicrobial Potential of Bacteria Associated with Marine Sea Slugs from North Sulawesi, Indonesia
- Author
-
Nils Böhringer, Katja M. Fisch, Dorothee Schillo, Robert Bara, Cora Hertzer, Fabian Grein, Jan-Hendrik Eisenbarth, Fontje Kaligis, Tanja Schneider, Heike Wägele, Gabriele M. König, and Till F. Schäberle
- Subjects
0301 basic medicine ,Microbiology (medical) ,natural product ,medicine.drug_class ,Microorganism ,Antibiotics ,lcsh:QR1-502 ,microbiome ,medicine.disease_cause ,01 natural sciences ,Microbiology ,lcsh:Microbiology ,antibiotics ,03 medical and health sciences ,chemistry.chemical_compound ,medicine ,marine Heterobranchia ,Nudibranchia ,Microbiome ,Escherichia coli ,Original Research ,Natural product ,biology ,010405 organic chemistry ,NRPS ,PKS ,Antimicrobial ,biology.organism_classification ,0104 chemical sciences ,Sea slug ,030104 developmental biology ,chemistry ,Bacteria - Abstract
Nudibranchia, marine soft-bodied organisms, developed, due to the absence of a protective shell, different strategies to protect themselves against putative predators and fouling organisms. One strategy is to use chemical weapons to distract predators, as well as pathogenic microorganisms. Hence, these gastropods take advantage of the incorporation of chemical molecules. Thereby the original source of these natural products varies; it might be the food source, de novo synthesis from the sea slug, or biosynthesis by associated bacteria. These bioactive molecules applied by the slugs can become important drug leads for future medicinal drugs. To test the potential of the associated bacteria, the latter were isolated from their hosts, brought into culture and extracts were prepared and tested for antimicrobial activities. From 49 isolated bacterial strains 35 showed antibiotic activity. The most promising extracts were chosen for further testing against relevant pathogens. In that way three strains showing activity against methicillin resistant Staphylococcus aureus (MRSA) and one strain with activity against enterohemorrhagic Escherichia coli (EHEC), respectively, were identified. The obtained results indicate that the sea slug associated microbiome is a promising source for bacterial strains, which hold the potential for the biotechnological production of antibiotics.
- Published
- 2017
3. Oxidative dearomatisation: the key step of sorbicillinoid biosynthesis
- Author
-
Russell J. Cox, Marija Avramovic, Anna Osipow, Thomas J. Simpson, Ahmed al Fahad, Jack R. Davison, Joern Piel, Craig P. Butts, Amira Abood, and Katja M. Fisch
- Subjects
biology ,General Chemistry ,biology.organism_classification ,Penicillium chrysogenum ,medicine.disease_cause ,Polyketide ,chemistry.chemical_compound ,Biochemistry ,Biosynthesis ,chemistry ,Aspergillus nidulans ,Polyketide synthase ,Gene cluster ,biology.protein ,medicine ,Gene ,Escherichia coli - Abstract
An FAD-dependent monooxygenase encoding gene (SorbC) was cloned from Penicillium chrysogenum E01-10/3 and expressed as a soluble protein in Escherichia coli. The enzyme efficiently performed the oxidative dearomatisation of sorbicillin and dihydrosorbicillin to give sorbicillinol and dihydrosorbicillinol respectively. Bioinformatic examination of the gene cluster surrounding SorbC indicated the presence of two polyketide synthase (PKS) encoding genes designated sorbA and sorbB. The gene sorbA-encodes a highly reducing iterative PKS while SorbB encodes a non-reducing iterative PKS which features a reductive release domain usually involved in the production of polyketide aldehydes. Using these observations and previously reported results from isotopic feeding experiments a new and simpler biosynthetic route to the sorbicillin class of secondary metabolites is proposed which is consistent with all reported experimental results.
- Published
- 2014
4. ChemInform Abstract: Toolbox for Antibiotics Discovery from Microorganisms
- Author
-
Till F. Schaeberle and Katja M. Fisch
- Subjects
medicine.drug_class ,Chemistry ,Microorganism ,Antibiotics ,medicine ,General Medicine ,Toolbox ,Microbiology - Published
- 2016
5. Regio- and Stereoselective Oxidative Phenol Coupling inAspergillus niger
- Author
-
Wolfgang Hüttel, Axel A. Brakhage, Michael Müller, Christian Gil Girol, Stefan Günther, Thorsten Heinekamp, Jörn Piel, and Katja M. Fisch
- Subjects
Models, Molecular ,Oxidative Coupling ,biology ,Stereochemistry ,Aspergillus niger ,Stereoisomerism ,General Chemistry ,biology.organism_classification ,Catalysis ,Coupling reaction ,chemistry.chemical_compound ,Polyketide ,Phenols ,chemistry ,Coumarins ,Polyketides ,Stereoselectivity ,Oxidative coupling of methane ,Homology modeling - Abstract
Piecing it together: Aspergillus niger produces kotanin by dimerization of the monomeric, polyketide-synthase-derived (PKS) 7-demethylsiderin. A combined approach, comprising bioinformatics and gene-deletion experiments, identified the biosynthetic cluster responsible for kotanin production. Homology modeling and substrate docking provide a rationale for the regio- and stereoselective phenol coupling reaction.
- Published
- 2012
6. Rational Domain Swaps Decipher Programming in Fungal Highly Reducing Polyketide Synthases and Resurrect an Extinct Metabolite
- Author
-
Thomas J. Simpson, Russell J. Cox, Ahmed A. Yakasai, Walid Bakeer, Colin M. Lazarus, Katja M. Fisch, Zahida Wasil, Zhongshu Song, Andy M. Bailey, and Jennifer Pedrick
- Subjects
Models, Molecular ,biology ,Pyridones ,Aspergillus oryzae ,Metabolite ,General Chemistry ,Computational biology ,biology.organism_classification ,Biochemistry ,Catalysis ,Domain (software engineering) ,Polyketide ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Biosynthesis ,Gene cluster ,Secondary metabolism ,Oxidation-Reduction ,Polyketide Synthases ,Gene - Abstract
The mechanism of programming of iterative highly reducing polyketide synthases remains one of the key unsolved problems of secondary metabolism. We conducted rational domain swaps between the polyketide synthases encoding the biosynthesis of the closely related compounds tenellin and desmethylbassianin. Expression of the hybrid synthetases in Aspergillus oryzae led to the production of reprogrammed compounds in which the changes to the methylation pattern and chain length could be mapped to the domain swaps. These experiments reveal for the first time the origin of programming in these systems. Domain swaps combined with coexpression of two cytochrome P450 encoding genes from the tenellin biosynthetic gene cluster led to the resurrection of the extinct metabolite bassianin.
- Published
- 2011
7. Trichopyrone and Other Constituents from the Marine Sponge-Derived Fungus Trichoderma sp
- Author
-
Katja M. Fisch, Anthony D. Wright, and Ahmed Abdel-Lateff
- Subjects
Models, Molecular ,Trichoderma ,Magnetic Resonance Spectroscopy ,Antioxidant ,biology ,Chemistry ,Stereochemistry ,medicine.medical_treatment ,Trichoderma viride ,Free Radical Scavengers ,Fungus ,biology.organism_classification ,Antimicrobial ,General Biochemistry, Genetics and Molecular Biology ,Porifera ,Sponge ,Polyketide ,Pyrones ,medicine ,Animals ,Bioassay ,Seawater ,Marine fungi - Abstract
The fungus Trichoderma viride was isolated from the Caribbean sponge Agelas dispar, which was collected from waters around the island of Dominica. Its EtOAc extract, exhibiting mild radical scavenging properties, was mass cultivated and found to produce a new pyranone derivative, trichopyrone (1), and ten compounds, namely four sorbicillinoid polyketide derivatives, trichodermanone A-D (2 - 5), two hexaketide derivatives, rezishanone (6) and vertinolide (7), three known dodecaketides, trichodimerol (8), bislongiquinolide (trichotetronine, 9), and bisvertinol (10), as well as 2-furancarboxylic acid (11). The structures of all compounds were determined by interpretation of their spectroscopic data (1D and 2D NMR, MS, UV and IR). The biological activities of all isolates were evaluated in a series of bioassays (radical scavenging, antioxidant, antimicrobial, inhibition of HIV-1 RT). The majority had very weak or no effects in the applied test systems
- Published
- 2009
8. New Antioxidant Hydroquinone Derivatives from the Algicolous Marine Fungus Acremonium sp
- Author
-
Ulrich Höller, Peter G. Jones, Katja M. Fisch, Ahmed Abdel-Lateff, Gabriele M. König, and Anthony D. Wright
- Subjects
Stereochemistry ,Carboxylic acid ,Molecular Conformation ,Pharmaceutical Science ,Crystallography, X-Ray ,Antioxidants ,Catalysis ,Gas Chromatography-Mass Spectrometry ,Analytical Chemistry ,Hydrolysis ,chemistry.chemical_compound ,Picrates ,Glucoside ,Drug Discovery ,Organic chemistry ,Pharmacology ,chemistry.chemical_classification ,Dose-Response Relationship, Drug ,Molecular Structure ,Hydroquinone ,Bicyclic molecule ,Biphenyl Compounds ,Organic Chemistry ,Glycoside ,Stereoisomerism ,Free Radical Scavengers ,HIV Reverse Transcriptase ,Hydroquinones ,Acremonium ,Biphenyl compound ,Complementary and alternative medicine ,chemistry ,Cyclization ,Lymphocyte Specific Protein Tyrosine Kinase p56(lck) ,Spain ,Molecular Medicine ,Aliphatic compound - Abstract
A marine fungal isolate, identified as Acremonium sp., was mass cultivated and found to produce two novel hydroquinone derivatives, 7-isopropenylbicyclo[4.2.0]octa-1,3,5-triene-2,5-diol (1) and 7-isopropenylbicyclo[4.2.0]octa-1,3,5-triene-2,5-diol-5-beta-D-glucopyranoside (2). Compound 1 and its glucoside 2 possess a most unusual ring system. The new natural products (3R,4S)-3,4-dihydroxy-7-methyl-3,4-dihydro-1(2H)naphthalenone (3) and (3S,4S)-3,4-dihydroxy-7-methyl-3,4-dihydro-1(2H)-naphthalenone (4) were obtained as a 1:0.8 mixture. 2-(1-Methylethylidene)pentanedioic acid (5) was isolated for the first time as a natural product and its structure proven by X-ray analysis. In addition to these compounds an inseparable mixture of three new isomeric compounds, pentanedioic acid 2-(1-methylethylidene)-5-methyl ester (6), pentanedioic acid 2-(1-methylethylidene)-1-methyl ester (7), and pentanedioic acid 2-(1-methylethenyl)-5-methyl ester (8), was also obtained. Isolated together with the new compounds were three known hydroquinone derivatives, 9, 10, and 11. The structures of all compounds were determined by interpretation of their spectroscopic data (1D and 2D NMR, MS, UV, and IR). Each isolate was tested for its antioxidant properties, and compounds 1 and 9-11 were found to have significant activity.
- Published
- 2002
9. Oxidative dearomatisation: the key step of sorbicillinoid biosynthesis†Electronic supplementary information (ESI) available: Containing all experimental details. See DOI: 10.1039/c3sc52911hClick here for additional data file
- Author
-
Ahmed Al, Fahad, Amira, Abood, Katja M, Fisch, Anna, Osipow, Jack, Davison, Marija, Avramović, Craig P, Butts, Jörn, Piel, Thomas J, Simpson, and Russell J, Cox
- Subjects
Chemistry - Abstract
A new biosynthetic pathway to the sorbicillinoid natural products is proposed based on the observation of oxidative dearomatisation of dihydrosorbicillin 10b., An FAD-dependent monooxygenase encoding gene (SorbC) was cloned from Penicillium chrysogenum E01-10/3 and expressed as a soluble protein in Escherichia coli. The enzyme efficiently performed the oxidative dearomatisation of sorbicillin and dihydrosorbicillin to give sorbicillinol and dihydrosorbicillinol respectively. Bioinformatic examination of the gene cluster surrounding SorbC indicated the presence of two polyketide synthase (PKS) encoding genes designated sorbA and sorbB. The gene sorbA-encodes a highly reducing iterative PKS while SorbB encodes a non-reducing iterative PKS which features a reductive release domain usually involved in the production of polyketide aldehydes. Using these observations and previously reported results from isotopic feeding experiments a new and simpler biosynthetic route to the sorbicillin class of secondary metabolites is proposed which is consistent with all reported experimental results.
- Published
- 2013
10. Catalytic role of the C-terminal domains of a fungal non-reducing polyketide synthase
- Author
-
David Ivison, Andy M. Bailey, Katja M. Fisch, Thomas J. Simpson, Colin M. Lazarus, Russell J. Cox, and Elizabeth Skellam
- Subjects
Stereochemistry ,Methylation ,Catalysis ,Fungal Proteins ,Hydrolysis ,In vivo ,Polyketide synthase ,Materials Chemistry ,Cloning, Molecular ,Glutamine amidotransferase ,ATP synthase ,biology ,Molecular Structure ,Chemistry ,Metals and Alloys ,General Chemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biochemistry ,Terpene synthase N terminal domain ,Ceramics and Composites ,biology.protein ,Biocatalysis ,Oxidation-Reduction ,Polyketide Synthases - Abstract
The in vivo activity of truncated forms of methylorcinaldehyde synthase shows that the synthase retains a hydrolytic release activity in the absence of reductive chain release and that chain-length is not controlled by the reductive release domain; experiments using a methyltransferase inhibitor suggest that methylation occurs prior to aromatisation.
- Published
- 2010
11. Antioxidant Metabolites from Marine Derived Fungi
- Author
-
Ahmed Abdel-Lateff, Katja M. Fisch, and Gabriele M. König
- Subjects
Antioxidant ,Chemistry ,medicine.medical_treatment ,medicine ,Food science - Published
- 2006
12. Inhibition früher Schritte der Metastasierung durch Blockade von FAK (Focal Adhesion Kinase) in vivo
- Author
-
Jörg Haier, A. von Sengbusch, K. Schlüter, and Katja M. Fisch
- Subjects
Extracellular matrix ,Focal adhesion ,Circulating tumor cell ,ddc: 610 ,Chemistry ,Kinase ,Adhesion ,Cell adhesion ,Extravasation ,Intracellular ,Cell biology - Abstract
Formation of tumor cell adhesion and following extravasation are limiting steps in organ specific metastasis. Focal Adhesion Kinase (FAK) plays a pivotal role in the intracellular signaling during cell adhesion and migration, which can be modulated by shear forces acting on circulating tumor cells. The intrinsic FAK inhibitor FRNK (FAK-related-non-kinase) was overexpressed in HEP G2 and HT-29 cells to investigate the role of FAK during early steps of metastasis. Static adhesion was not influenced by FRNK expression, whereas dynamic adhesion under flow conditions was dramatically reduced, apparent by significant reduced dynamic adhesion rates DAR (FRNK+: 12 ± 9 cells vs. FRNK-: 32 ± 10 cells; p 80%, p < 0.001) and complete inhibition of migration of the cells to the parenchyma. Our results indicate that FAK is involved in stabilization of cell adhesion on extracellular matrix in vitro and in vivo, which allows circulating tumor cells to resist the shear forces. This kinase is therefore involved in the regulation of rate limiting steps in distant metastasis formation.
- Published
- 2005
13. A new antioxidant isobenzofuranone derivative from the algicolous marine fungus Epicoccum sp
- Author
-
Katja M. Fisch, Gabriele M. König, Ahmed Abdel-Lateff, and Anthony D. Wright
- Subjects
Antioxidant ,Magnetic Resonance Spectroscopy ,DPPH ,Linolenic acid ,Stereochemistry ,medicine.medical_treatment ,Pharmaceutical Science ,Fucus vesiculosus ,Secondary metabolite ,Antioxidants ,Gas Chromatography-Mass Spectrometry ,Analytical Chemistry ,chemistry.chemical_compound ,Picrates ,Drug Discovery ,Botany ,medicine ,TBARS ,Humans ,Hydroxymethyl ,Seawater ,Chromatography, High Pressure Liquid ,Pharmacology ,Natural product ,biology ,Plant Extracts ,Organic Chemistry ,Biphenyl Compounds ,Fungi ,alpha-Linolenic Acid ,biology.organism_classification ,Complementary and alternative medicine ,chemistry ,Molecular Medicine ,medicine.drug ,Phytotherapy - Abstract
The fungus Epicoccum sp., was isolated from the marine brown alga Fucus vesiculosus. After cultivation the fungus was investigated for its secondary metabolite content, and found to contain the new natural product 4,5,6-trihydroxy-7-methylphthalide (1, epicoccone), together with 5-(acetoxymethyl)-furan-2-carboxylic acid (2), furan-2-carboxylic acid (3), 5-(hydroxymethyl)-furan-2-carboxylic acid (4), (-)-(3 R,4 S)-4-hydroxymellein (5), and (-)-(3 R)-5-hydroxymellein (6). The structures of all compounds were determined by interpretation of their spectroscopic data (1D and 2D NMR, MS, UV, optical rotation and IR). Each isolate was tested for its antioxidative properties. Compound 1 was found to be potently active, showing 95 % DPPH radical scavenging effects at 25 microg/mL. Compound 1 also inhibited the peroxidation of linolenic acid in the TBARS assay (62 % inhibition at 37 microg/mL).
- Published
- 2003
14. Antioxidative meroterpenoids from the brown alga Cystoseira crinita
- Author
-
Katja M. Fisch, Gabriele M. König, Volker Böhm, and Anthony D Wright
- Subjects
Antioxidant ,DPPH ,medicine.medical_treatment ,Pharmaceutical Science ,Chlorella ,Pharmacognosy ,Phaeophyta ,Antioxidants ,Analytical Chemistry ,chemistry.chemical_compound ,Picrates ,Drug Discovery ,medicine ,TBARS ,Escherichia coli ,Organic chemistry ,Nuclear Magnetic Resonance, Biomolecular ,Pharmacology ,Molecular Structure ,Terpenes ,Organic Chemistry ,Biphenyl Compounds ,Fungi ,Stereoisomerism ,Terpenoid ,HIV Reverse Transcriptase ,Quinone ,Hydroquinones ,Biphenyl compound ,Complementary and alternative medicine ,chemistry ,Italy ,Bacillus megaterium ,Molecular Medicine ,Reverse Transcriptase Inhibitors ,Aliphatic compound ,Algorithms - Abstract
Six new tetraprenyltoluquinol derivatives (1-6), two new triprenyltoluquinol derivatives (7 and 8), and two new tetraprenyltoluquinone derivatives (9 and 10) were isolated from the brown alga Cystoseira crinita Duby together with four known tetraprenyltoluquinol derivatives (11-14). All structures were elucidated by employing spectroscopic techniques (NMR, MS, UV, and IR). Each compound was evaluated for its antioxidative properties in the TBARS and DPPH assay, and compounds 1, 2, 6, and 10-14 were additionally assessed in the TEAC and PCL assay. Hydroquinones were found to have powerful antioxidant activity.
- Published
- 2003
15. Biosynthesis of natural products by microbial iterative hybrid PKS–NRPS
- Author
-
Katja M. Fisch
- Subjects
chemistry.chemical_classification ,biology ,General Chemical Engineering ,Peptide Synthetases ,General Chemistry ,Ribosomal RNA ,biology.organism_classification ,chemistry.chemical_compound ,Polyketide ,Enzyme ,Biosynthesis ,chemistry ,Biochemistry ,polycyclic compounds ,Bacteria - Abstract
This review discusses the biosynthesis of natural products generated by iterative hybrid polyketide synthases–non ribosomal peptide synthetases (PKS–NRPS) from fungi and bacteria, the programming of the enzymes and bioengineering approaches.
- Published
- 2013
16. The programming role of trans-acting enoyl reductases during the biosynthesis of highly reduced fungal polyketides
- Author
-
Zahida Wasil, Ahmed A. Yakasai, Andy M. Bailey, Khomaizon A. Kadir, Russell J. Cox, Walid Bakeer, Thomas J. Simpson, Katherine Williams, Katja M. Fisch, Mary N. Heneghan, and Colin M. Lazarus
- Subjects
chemistry.chemical_classification ,biology ,Stereochemistry ,General Chemistry ,Reductase ,biology.organism_classification ,chemistry.chemical_compound ,Enzyme ,Biosynthesis ,chemistry ,Biochemistry ,Aspergillus oryzae ,Nonribosomal peptide ,Polyketide synthase ,polycyclic compounds ,biology.protein ,Trans-acting ,Gene - Abstract
A novel polyketide synthase nonribosomal peptide synthetase (PKS-NRPS) genecluster was isolated from Beauveria bassiania 992.05. The cluster encodes the enzymes responsible for the biosynthesis of the new 2-pyridone desmethylbassianin (DMB). DMB is structurally related to tenellin from B. bassiana 110.25 but it differs in chain length and degree of methylation. Despite these programming differences the 20 kb DMB biosynthetic genecluster has 90% sequence identity to the tenellingenecluster. Silencing of the PKS-NRPS gene, dmbS, resulted in total loss of DMB production. Co-expression of dmbS in Aspergillus oryzae with its cognate trans-actingenoyl reductase gene, dmbC, produced predesmethylbassianin A, the first isolable precursor in the biosynthetic pathway. Expression of dmbS with the tenellintrans-actingenoyl reductase gene, tenC, also resulted in the production of predesmethylbassianin A. Co-expression of tenS, the tenellin PKS-NRPS, with dmbC produced pretenellin A. These results show that the tenS and dmbS encoded PKS-NRPS contains the programme for polyketide biosynthesis, while the trans-actingERs appear to control the fidelity of the programme. Expression of a hybrid synthetase in which the PKS of the tenellin synthetase was fused to the NRPS from DMBS produced prototenellins A to C, indicating that the NRPS does not act as a selecting gatekeeper to affect the PKS programme.
- Published
- 2011
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.