2002 Fiscal Year Final Research Report Summary
Analysis of the biosynthetic gene of a polyketide-peptide hybrid type antibiotic produced by a myxobacterium
| Project/Area Number |
12480172
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bioorganic chemistry
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| Research Institution | Nagoya university |
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Principal Investigator |
OJIKA Makoto Nagoya university Graduate school of bioagricultural sciences Professor, 大学院・生命農学研究科, 教授 (50152492)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAGAMI Youji Nagoya university Graduate school of bioagricultural sciences Professor, 大学院・生命農学研究科, 教授 (80107408)
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| Project Period (FY) |
2000 – 2002
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| Keywords | myxobacteria / polyketide biosynthesis / biosynthetic gene / antifungal / cytotoxic / molecular biology |
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| Research Abstract |
Cystothiazole A is an antifungal and cytotoxic metabolite isolated from the myxobacteria Cystobacter fuscus by us and inhibits the mitochondrial respiratory chain. To produce the antibiotic and its congener by metabolic and genetic engineering, we tried to explore the biosynthetic route and genes of cystothiazole A. Firstly the biosynthetic precursors (acetate, propionate, cysteine, and valine) were determined by feeding experiments, indicating that this metabolite is a polyketide-peptide hybrid type antibiotic. Several related metabolites isolated from culture broth of C.fuscus were found to be produced by oxidative metabolism of cystothiazole A by the producer itself by experiments of external addition of cystothiazole A into culture broth. Based on these preliminary results, we designed PCR primers derived from highly conserved resions of β-ketosynthase (KS) genes of polyketide synthases (PKS) genes. After PCR experiments using the genomic DNA as template, a fragment of 700 bp that shows high homology with a KS sequence of a known myxobacterial antibiotic was isolated. The gene walking experiments using the specific sequence of this fragment was carried out to reveal total 30-kbp regions of the restriction map, which is estimated to correspond to approximately 80% of the biosynthetic gene cluster of cystothiazole A. The search for the unknown ca.6-kbp region, sequencing analysis, and functional analysis are now in progress.
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