title: Analysis and refactoring of the A-74528 biosynthetic pathway.
abstract: A-74528 is a C30 polyketide natural product that functions as an inhibitor of 2',5'-oligoadenylate phosphodiesterase (2'-PDE), a key regulatory enzyme of the interferon pathway. Modulation of 2'-PDE represents a unique therapeutic approach for regulating viral infections. The gene cluster responsible for biosynthesis of A-74528 yields minute amounts of this natural product together with considerably larger quantities of a structurally dissimilar C30 cytotoxic agent, fredericamycin. Through construction and analysis of a series of knockout mutants, we identified the genes necessary for A-74528 biosynthesis. Remarkably, the formation of six stereocenters and the regiospecific formation of six rings in A-74528 appear to be catalyzed by only two tailoring enzymes, a cyclase and an oxygenase, in addition to the core polyketide synthase. The inferred pathway was genetically refactored in a heterologous host, Streptomyces coelicolor CH999, to produce 3 mg/L A-74528 in the absence of fredericamycin.
authors: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors: Jay T
authors: JT
authors: Fitzgerald
authors: Louise K
authors: LK
authors: Charkoudian
authors: Katharine R
authors: KR
authors: Watts
authors: Chaitan
authors: C
authors: Khosla
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D015394:Molecular Structure; D010105:Oxygenases / Q000378:metabolism*; D011083:Polycyclic Compounds / Q000737:chemistry / Q000378:metabolism*; D011753:Pyrones / Q000737:chemistry / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000737:chemistry / Q000378:metabolism*
chemical_list: C506219:A-74528; D011083:Polycyclic Compounds; D011753:Pyrones; D010105:Oxygenases; D000262:Adenylyl Cyclases