Structure and biosynthesis of the marine streptomycete ansamycin ansalactam A and its distinctive branched chain polyketide extender unit.
Reported is the structure and biosynthesis of ansalactam A, an ansamycin class polyketide produced by an unusual modification of the polyketide pathway. This new metabolite, produced by a marine sediment-derived bacterium of the genus  Streptomyces , possesses a novel spiro γ-lactam moiety and a distinctive isobutyryl polyketide fragment observed for the first time in this class of natural products. The structure of ansalactam A was defined by spectroscopic methods including X-ray crystallographic analysis. Biosynthetic studies with stable isotopes further led to the discovery of a new, branched chain polyketide synthase extender unit derived from (E)-4-methyl-2-pentenoic acid for polyketide assembly observed for the first time in this class of natural products.
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0204, United States.
Micheal C
MC
Wilson
Sang-Jip
SJ
Nam
Tobias A M
TA
Gulder
Christopher A
CA
Kauffman
Paul R
PR
Jensen
William
W
Fenical
Bradley S
BS
Moore
D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry*; D059001:Aquatic Organisms / Q000378:metabolism*; D001688:Biological Products / Q000737:chemistry / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology; D048630:Polyketide Synthases / Q000737:chemistry / Q000378:metabolism; D061065:Polyketides / Q000737:chemistry* / Q000378:metabolism; D017828:Rifabutin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism*; D013302:Streptomyces / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001688:Biological Products; D061065:Polyketides; C572734:ansalactam A; D017828:Rifabutin; D048630:Polyketide Synthases
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