Open AccessBiosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism
Author(s) -
Steven G. Van Lanen,
Shuangjun Lin,
Ben Shen
Publication year - 2008
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0708750105
Subject(s) - enediyne , biochemistry , chemistry , stereochemistry , biosynthesis , enzyme , atp synthase
C-1027 is an enediyne antitumor antibiotic composed of four distinct moieties: an enediyne core, a deoxy aminosugar, a β-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.