Substrate flexibility of vicenisaminyltransferase VinC involved in the biosynthesis of vicenistatin.
Substrate flexibility of vicenisaminyltransferase VinC involved in the biosynthesis of vicenistatin.
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DOI：
10.1021/ja0685250
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发表时间：
2007-03
影响因子：
15
通讯作者：
A. Minami;T. Eguchi
中科院分区：
文献类型：
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作者：
A. Minami;T. Eguchi
一种糖基转移酶VinC参与抗肿瘤β -糖苷类抗生素vicenistatin的生物合成。它催化dtdp - α - d -维森胺和维森内酰胺之间的糖基转移反应。先前鉴定其对各种糖基受体的广泛底物特异性使我们能够探索VinC在糖多样化方面的潜力。体外研究了vicenilactam对几种dtdp -2-脱氧-d糖的底物特异性，发现VinC与几种dtdp -2-脱氧-d糖（如mycarose， digitoxose， olivose和2-脱氧葡萄糖）的α -异位体具有活性，以提供各自的β -糖苷。值得注意的是，dtdp -2-脱氧-d糖的β -异头物似乎也被VinC接受形成α -糖苷。此外，VinC还能催化dTDP-l-mycarose的α -异头体和β -异头体分别转化为β -糖苷和α -糖苷的糖基转移反应。这些结果表明VinC是一种独特的糖基转移酶，具有广泛的底物特异性。这种轴向糖苷键的形成机理可以用糖基转移反应中dtdp糖的构象转变为船形构象来解释。为了利用VinC的这些特征进行糖多样化，我们利用非天然糖基供体和受体构建了22组结构多样化的糖苷。
A glycosyltransferase VinC is involved in the biosynthesis of antitumor beta-glycoside antibiotic vicenistatin. It catalyzes a glycosyl transfer reaction between dTDP-alpha-D-vicenisamine and vicenilactam. Previous identification of its broad substrate specificity toward various glycosyl acceptors enabled us to explore the potential of VinC for glycodiversification. In vitro study of the substrate specificity toward several dTDP-sugars with vicenilactam established that VinC displayed activities with alpha-anomers of several dTDP-2-deoxy-D-sugars such as mycarose, digitoxose, olivose, and 2-deoxyglucose to afford respective beta-glycosides. Notably, beta-anomers of dTDP-2-deoxy-D-sugars also appeared to be accepted by VinC to form alpha-glycosides. Furthermore, VinC is capable of catalyzing glycosyl transfer reactions from both the alpha-anomer and beta-anomer of dTDP-l-mycarose, respectively, into beta-glycoside and alpha-glycoside. These results indicate that VinC is a unique glycosyltransferase possessing broad substrate specificity. The mechanism of this axially oriented glycosidic bond formation from the equatorially oriented dTDP-sugar might be explained by conformational change of dTDP-sugar to a boat conformation during the glycosyl transfer reaction. To apply these features of VinC for glycodiversification, 22 sets of structurally diverse glycosides were constructed using unnatural glycosyl donors and acceptors.