Novel avermectins produced by mutational biosynthesis.

Dutton, Christopher J.; Gibson, S.P.; Goudie, A. C.; Holdom, Kelvin S.; Pacey, Michael S.; Ruddock, John C.; Bu’Lock, J. D.; Richards, Michelle

doi:10.7164/antibiotics.44.357

Cited by 164 publications

(102 citation statements)

References 19 publications

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“…5. The latter greatly facilitates the development of a larger selection of S. avermitilis bkd strains that can be used to generate valuable novel (unnatural) C-25-substituted antiparasitic avermectins (15).…”

Section: Vol 177 1995 S Avermitilis Bkdf Mutant and Avermectin Promentioning

confidence: 99%

“…The mutant could synthesize natural avermectins only when the ␣-branched-chain fatty acids or a precursor bearing the isopropyl or sec-butyl (S-form) group was added to the fermentation medium ( Fig. 1, bottom), while supplementation with a wide variety of alternative fatty acids results in the formation of a corresponding series of novel avermectins (15). These results are possible since short-chain fatty acids are readily taken up by S. avermitilis from the fermentation medium in a process that has been postulated to require at least a fatty acid binding and transport protein (probably similar to the Escherichia coli FadL protein) and a membrane-associated acylCoA synthetase (probably similar to the E. coli FadD protein) (17).…”

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confidence: 99%

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A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins

et al. 1995

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A second cluster of genes encoding the E1␣, E1␤, and E2 subunits of branched-chain ␣-keto acid dehydrogenase (BCDH), bkdFGH, has been cloned and characterized from Streptomyces avermitilis, the soil microorganism which produces anthelmintic avermectins. Open reading frame 1 (ORF1) (bkdF, encoding E1␣), would encode a polypeptide of 44,394 Da (406 amino acids). The putative start codon of the incompletely sequenced ORF2 (bkdG, encoding E1␤) is located 83 bp downstream from the end of ORF1. The deduced amino acid sequence of bkdF resembled the corresponding E1␣ subunit of several prokaryotic and eukaryotic BCDH complexes. An S. avermitilis bkd mutant constructed by deletion of a genomic region comprising the 5 end of bkdF is also described. The mutant exhibited a typical Bkd ؊ phenotype: it lacked E1 BCDH activity and had lost the ability to grow on solid minimal medium containing isoleucine, leucine, and valine as sole carbon sources. Since BCDH provides an ␣-branched-chain fatty acid starter unit, either S(؉)-␣-methylbutyryl coenzyme A or isobutyryl coenzyme A, which is essential to initiate the synthesis of the avermectin polyketide backbone in S. avermitilis, the disrupted mutant cannot make the natural avermectins in a medium lacking both S(؉)-␣-methylbutyrate and isobutyrate. Supplementation with either one of these compounds restores production of the corresponding natural avermectins, while supplementation of the medium with alternative fatty acids results in the formation of novel avermectins. These results verify that the BCDH-catalyzed reaction of branched-chain amino acid catabolism constitutes a crucial step to provide fatty acid precursors for antibiotic biosynthesis in S. avermitilis.

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Section: Vol 177 1995 S Avermitilis Bkdf Mutant and Avermectin Promentioning

confidence: 99%

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confidence: 99%

A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins

et al. 1995

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“…The degradation products of these amino acids are isovaleryl-CoA, isobutyryl-CoA, and 2-methylbutyryl-CoA, respectively (12), which are used as starting units for iso-and anteiso-fatty acids and also for several secondary metabolites from different bacteria (e.g. avermectin from Streptomyces avermitilis (13) or myxothiazol (14), myxalamides (15), and aurafuron 2 The abbreviations used are: Bkd, branched-chain keto acid dehydrogenase; FA, fatty acid; SCFA, straight-chain fatty acid; FAME, fatty acid methyl ester; IVA, isovalerate; iso15:0, 13-methyltetradecanoate; MvaS, 3-hydroxy-3-methylglutaryl-CoA synthase; kan, kanamycin; PE, phosphatidylethanolamine; di-iso15:0-PE, 1,2-di-(-O-(13-methyltetradecanoyl)glycero-3-phosphatidylethanolamine; VEPE, 1-O-(13-methyl-1-Z-tetradecenyl)-2-O-(13-methyltetradecanoyl)glycero-3-phosphatidylethanolamine; AEPE, 1-O-(13-methyltetradecyl)-2-O-(13-methyltetradecanoyl)glycero-3-phosphatidylethanolamine; TG-1, 1,2-di-(13-methyltetradecanoyl)-3-(13-methyltetradecyl)glycerol; TG-2, 1,2-di-(hexadecanoyl)-3-(13-methyltetradecyl)glycerol; TPG, glycerol tripalmitate; GC, gas chromatography; MS, mass spectrometry; MS/MS, tandem mass spectrometry; HPLC, high performance liquid chromatography; ESI, electrospray ionization; PR, peripheral rod.…”

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confidence: 99%

Novel Iso-branched Ether Lipids as Specific Markers of Developmental Sporulation in the Myxobacterium Myxococcus xanthus

Ring

Schwär

Thiel

et al. 2006

Journal of Biological Chemistry

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Myxobacteria are Gram-negative soil bacteria that can form fruiting bodies under starvation conditions (1). These fruiting bodies are visible to the naked eye and can reach a tree-like complexity in some species. During the developmental process, a certain amount of vegetative cells differentiates into heat-and desiccation-resistant myxospores enabling the survival of the colony. The model organism to study this highly complex process is Myxococcus xanthus from which different extracellular signals and regulators have already been described that can be combined in a model likely reflecting the essential parts of the underlying regulatory network (2, 3). However, the biochemical changes that are involved in this process or appear as a result of it have been barely identified. That biochemical changes occur is evident from change in cell shape from vegetative rods to round myxospores with thick spore coats (4, 5) and high amounts of trehalose (6), which is proposed to act as a compatible solute. Furthermore, the pioneering work of White and co-workers (7-9) showed that several enzymes involved in increase of carbohydrate biosynthesis are induced during sporulation.Ten years ago, Downard and coworkers identified a mutant that was disrupted in the branched-chain keto acid dehydrogenase (Bkd) 2 complex, which resulted in a developmental phenotype forming almost no aggregates or spores under starvation conditions (10). The Bkd complex is involved in the degradation of the branched-chain amino acids leucine, valine, and isoleucine, with all three being essential amino acids for M. xanthus (11). The degradation products of these amino acids are isovaleryl-CoA, isobutyryl-CoA, and 2-methylbutyryl-CoA, respectively (12), which are used as starting units for iso-and anteiso-fatty acids and also for several secondary metabolites from different bacteria (e.g. avermectin from Streptomyces avermitilis (13) or myxothiazol (14), myxalamides (15), and aurafuron * This work was supported by Deutsche Forschungsgemeinschaft Grants Bo1834/3-1 and Bo1834/4-1 (to H. B. B.) and Schu984/6-1 (to S. S.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. □ S The on-line version of this article (available at http://www.jbc.org) contains supplemental text and references. 1 To whom correspondence should be addressed. Tel.: 49-681-302-5494; Fax:49-681-302-5473; E-mail: h.bode@mx.uni-saarland.de.2 The abbreviations used are: Bkd, branched-chain keto acid dehydrogenase; FA, fatty acid; SCFA, straight-chain fatty acid; FAME, fatty acid methyl ester; IVA, isovalerate;

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“…Besides being important intermediates in the degradation of these abundant amino acids, the thioesters are important starting units in the biosynthesis of secondary metabolites and fatty acids (FAs). Well-known examples for IB-CoA-or 2MB-CoA-primed secondary metabolites are the avermectins (8), but there are also several secondary metabolites that use IV-CoA as a starting unit (e.g., myxothiazol [24] and aurafuron [15]). In FA biosynthesis, IV-CoA, IB-CoA, and 2MB-CoA are the starting units of iso-odd, iso-even, and ante-iso-odd FAs, respectively, which can be found in various bacteria and can substitute for unsaturated fatty acids to maintain membrane fluidity at different temperatures (12).…”

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confidence: 99%

3-Hydroxy-3-Methylglutaryl-Coenzyme A (CoA) Synthase Is Involved in Biosynthesis of Isovaleryl-CoA in the Myxobacterium Myxococcus xanthus during Fruiting Body Formation

et al. 2006

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Isovaleryl-coenzyme A (IV-CoA) is the starting unit for some secondary metabolites and iso-odd fatty acids in several bacteria. According to textbook biochemistry, IV-CoA is derived from leucine degradation, but recently an alternative pathway that branches from the well-known mevalonate-dependent isoprenoid biosynthesis has been described for myxobacteria. A double mutant was constructed in Myxococcus xanthus by deletion of genes involved in leucine degradation and disruption of mvaS encoding the 3-hydroxy-3-methylglutarylcoenzyme A synthase. A dramatic decrease of IV-CoA-derived iso-odd fatty acids was observed for the mutant, confirming mvaS to be involved in the alternative pathway. Additional quantitative real-time reverse transcription-PCR experiments indicated that mvaS is transcriptionally regulated by isovalerate. Furthermore, feeding studies employing an intermediate specific for the alternative pathway revealed that this pathway is induced during fruiting body formation, which presumably increases the amount of IV-CoA available when leucine is limited.

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Novel avermectins produced by mutational biosynthesis.

Cited by 164 publications

References 19 publications

A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins

A second branched-chain alpha-keto acid dehydrogenase gene cluster (bkdFGH) from Streptomyces avermitilis: its relationship to avermectin biosynthesis and the construction of a bkdF mutant suitable for the production of novel antiparasitic avermectins

Novel Iso-branched Ether Lipids as Specific Markers of Developmental Sporulation in the Myxobacterium Myxococcus xanthus

3-Hydroxy-3-Methylglutaryl-Coenzyme A (CoA) Synthase Is Involved in Biosynthesis of Isovaleryl-CoA in the Myxobacterium Myxococcus xanthus during Fruiting Body Formation

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