title: Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism.
abstract: C-1027 is an enediyne antitumor antibiotic composed of four distinct moieties: an enediyne core, a deoxy aminosugar, a beta-amino acid, and a benzoxazolinate moiety. We now show that the benzoxazolinate moiety is derived from chorismate by the sequential action of two enzymes-SgcD, a 2-amino-2-deoxyisochorismate (ADIC) synthase and SgcG, an iron-sulfur, FMN-dependent ADIC dehydrogenase-to generate 3-enolpyruvoylanthranilate (OPA), a new intermediate in chorismate metabolism. The functional elucidation and catalytic properties of each enzyme are described, including spectroscopic characterization of the products and the development of a fluorescence-based assay for kinetic analysis. SgcD joins isochorismate (IC) synthase and 4-amino-4-deoxychorismate (ADC) synthase as anthranilate synthase component I (ASI) homologues that are devoid of pyruvate lyase activity inherent in ASI; yet, in contrast to IC and ADC synthase, SgcD has retained the ability to aminate chorismate identically to that observed for ASI. The net conversion of chorismate to OPA by the tandem action of SgcD and SgcG unambiguously establishes a new branching point in chorismate metabolism.
authors.affiliation: Division of Pharmaceutical Sciences, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Van Lanen
authors.forename: Shuangjun
authors.initials: S
authors.lastname: Lin
authors.forename: Ben
authors.initials: B
authors.lastname: Shen
mesh_terms: D026905:Amino Acid Transport Systems / Q000378:metabolism; D000617:Aminoglycosides / Q000737:chemistry* / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017920:Antiporters / Q000378:metabolism; D001665:Binding Sites; D002827:Chorismic Acid / Q000378:metabolism*; D002833:Choroiditis; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology; D004247:DNA / Q000737:chemistry; D053281:Enediynes / Q000737:chemistry* / Q000494:pharmacology*; D029968:Escherichia coli Proteins / Q000378:metabolism; D007700:Kinetics; D008956:Models, Chemical; D009369:Neoplasms / Q000188:drug therapy*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry / Q000494:pharmacology*; D013302:Streptomyces / Q000378:metabolism; D000637:Transaminases / Q000737:chemistry / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000737:chemistry
chemical_list: C526270:3-enolpyruvoylanthranilate; C476528:AdiC protein, E coli; D026905:Amino Acid Transport Systems; D000617:Aminoglycosides; D000970:Antineoplastic Agents; D017920:Antiporters; D053281:Enediynes; D029968:Escherichia coli Proteins; D062367:ortho-Aminobenzoates; C058024:C 1027; D004247:DNA; C526272:2-amino-2-deoxyisochorismate dehydrogenase, Streptomyces globisporus; D044925:Oxidoreductases Acting on CH-CH Group Donors; C526271:2-amino-2-deoxyisochorismate synthase, Streptomyces globisporus; D000637:Transaminases; D002827:Chorismic Acid