Increased valinomycin production in mutants of Streptomyces sp. M10 defective in bafilomycin biosynthesis and branched-chain α-keto acid dehydrogenase complex expression.
Streptomyces sp. M10 is a valinomycin-producing bacterial strain that shows potent bioactivity against Botrytis blight of cucumber plants. During studies to increase the yield of valinomycin (a cyclododecadepsipeptide) in strain M10, additional antifungal metabolites, including bafilomycin derivatives (macrolide antibiotics), were identified. To examine the effect of bafilomycin biosynthesis on valinomycin production, the bafilomycin biosynthetic gene cluster was cloned from the genome of strain M10, as were two branched-chain α-keto acid dehydrogenase (BCDH) gene clusters related to precursor supply for bafilomycin biosynthesis. A null mutant (M10bafm) of one bafilomycin biosynthetic gene (bafV) failed to produce bafilomycin, but resulted in a 1.2- to 1.5-fold increase in the amount of valinomycin produced. In another null mutant (M10bkdFm) of a gene encoding a subunit of the BCDH complex (bkdF), bafilomycin production was completely abolished and valinomycin production increased fourfold relative to that in the wild-type M10 strain. The higher valinomycin yield was likely the result of redistribution of the metabolic flux from bafilomycin to valinomycin biosynthesis, because the two antibiotics share a common precursor, 2-ketoisovaleric acid, a deamination product of valine. The results show that directing precursor flux toward active ingredient biosynthesis could be used as a prospective tool to increase the competence of biofungicides.
Plant Pharmacology Laboratory, Department of Biosystems and Biotechnology, Korea University Graduate School, Seoul, 136-713, Republic of Korea.
Dong Wan
DW
Lee
Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Republic of Korea.
Bee Gek
BG
Ng
Plant Pharmacology Laboratory, Department of Biosystems and Biotechnology, Korea University Graduate School, Seoul, 136-713, Republic of Korea. biskim@korea.ac.kr.|Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, Republic of Korea. biskim@korea.ac.kr.
Beom Seok
BS
Kim
D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) / Q000172:deficiency / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D000935:Antifungal Agents / Q000378:metabolism; D045782:Hemiterpenes; D007651:Keto Acids / Q000378:metabolism; D018942:Macrolides / Q000378:metabolism*; D005810:Multigene Family / Q000235:genetics; D011446:Prospective Studies; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism*; D014634:Valinomycin / Q000096:biosynthesis*
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D045782:Hemiterpenes; D007651:Keto Acids; D018942:Macrolides; D014634:Valinomycin; C001505:alpha-ketoisovalerate; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Antifungal metabolite; Bafilomycin biofungicide; Biosynthetic gene cluster; Branched-chain α-keto acid dehydrogenase; Streptomyces; Valinomycin