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Characterization of the sgcf epoxide hydrolase supporting an (r)-vicinal diol intermediate for enediyne antitumor antibiotic c-1027 biosynthesis

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Overview

authors

  • Lin, S. J.
  • Horsman, G. P.
  • Chen, Y. H.
  • Li, W. L.
  • Shen, Ben

publication date

  • November 2009

journal

  • Journal of the American Chemical Society  Journal

abstract

  • C-1027 is a chromoprotein antitumor antibiotic consisting of an apoprotein and the C-1027 chromophore. The C-1027 chromophore possesses four distinct structural moieties-an enediyne core, a deoxy aminosugar, a benzoxazolinate, and an (S)-3-chloro-5-hydroxy-beta-tyrosine-the latter two of which are proposed to be appended to the enediyne core via a convergent biosynthetic strategy. Here we report the in vitro characterization of SgcF, an epoxide hydrolase from the C-1027 biosynthetic gene cluster that catalyzes regio- and stereospecific hydrolysis of styrene oxide, serving as an enediyne core epoxide intermediate mimic, to form a vicinal diol. Abolishment of C-1027 production in the DeltasgcF mutant strain Streptomyces globisporus SB1010 unambiguously establishes that sgcF plays an indispensable role in C-1027 biosynthesis. SgcF efficiently hydrolyzes (S)-styrene oxide, displaying an apparent K(m) of 0.6 +/- 0.1 mM and k(cat) of 48 +/- 1 min(-1), via attack at the alpha-position to exclusively generate the (R)-phenyl vicinal diol, consistent with the stereochemistry of the C-1027 chromophore. These findings support the role of SgcF in the proposed convergent pathway for C-1027 biosynthesis, unveiling an (R)-vicinal diol as a key intermediate. Interestingly, SgcF can also hydrolyze (R)-styrene oxide to afford preferentially the (R)-phenyl vicinal diol via attack at the beta-position, albeit with significantly reduced efficiency (apparent K(m) of 2.0 +/- 0.4 mM and k(cat) = 4.3 +/- 0.3 min(-1)). Although the latter activity unlikely contributes to C-1027 biosynthesis in vivo, such enantioconvergence arising from complementary regioselective hydrolysis of a racemic substrate could be exploited to engineer epoxide hydrolases with improved regio- and/or enantiospecificity.

subject areas

  • Antibiotics, Antineoplastic
  • Epoxide Hydrolases
  • Molecular Conformation
  • Stereoisomerism
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Identity

PubMed Central ID

  • PMC2783762

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/ja901242s

PubMed ID

  • 19856960
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Additional Document Info

start page

  • 16410

end page

  • 16417

volume

  • 131

issue

  • 45

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