Characterization of the SgcF Epoxide Hydrolase Supporting an (R)-Vicinal Diol Intermediate for Enediyne Antitumor Antibiotic C-1027 Biosynthesis,Journal of the American Chemical Society

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Characterization of the SgcF Epoxide Hydrolase Supporting an (R)-Vicinal Diol Intermediate for Enediyne Antitumor Antibiotic C-1027 Biosynthesis
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2009-11-18 , DOI: 10.1021/ja901242s
Shuangjun Lin ₁ , Geoffrey P Horsman , Yihua Chen , Wenli Li , Ben Shen

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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.

中文翻译：

支持用于烯二炔抗肿瘤抗生素 C-1027 生物合成的 (R)-邻二醇中间体的 SgcF 环氧化物水解酶的表征

C-1027 是一种色蛋白抗肿瘤抗生素，由载脂蛋白和 C-1027 生色团组成。C-1027 发色团具有四个不同的结构部分——一个烯二炔核心、一个脱氧氨基糖、一个苯并恶唑啉酸盐和一个 (S)-3-氯-5-羟基-β-酪氨酸——后两个被提议附加通过收敛的生物合成策略到达烯二炔核心。在这里，我们报告了 SgcF 的体外表征，这是一种来自 C-1027 生物合成基因簇的环氧化物水解酶，可催化氧化苯乙烯的区域和立体定向水解，作为烯二炔核心环氧化物中间体模拟物，形成邻二醇。DeltasgcF 突变菌株 Streptomyces globisporus SB1010 中 C-1027 生产的废除明确表明 sgcF 在 C-1027 生物合成中起着不可或缺的作用。SgcF 有效地水解 (S)-氧化苯乙烯，显示表观 K(m) 为 0.6 +/- 0.1 mM 和 k(cat) 为 48 +/- 1 min(-1)，通过在 alpha 位置进行攻击以专门生成 (R)-苯基邻二醇，与 C-1027 发色团的立体化学一致。这些发现支持 SgcF 在拟议的 C-1027 生物合成收敛途径中的作用，揭示了 (R)-邻二醇作为关键中间体。有趣的是，SgcF 还可以水解 (R)-氧化苯乙烯，通过攻击 β 位优先提供 (R)-苯基邻二醇，尽管效率显着降低（表观 K(m) 为 2.0 +/- 0.4 mM 和k（猫）= 4.3 +/- 0.3 分钟（-1））。尽管后一种活性不太可能有助于体内 C-1027 的生物合成，

更新日期：2009-11-18

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