Weissman K J, Bycroft M, Staunton J, Leadlay P F
Cambridge Centre for Molecular Recognition and Department of Organic Chemistry, University of Cambridge, Cambridge, UK.
Biochemistry. 1998 Aug 4;37(31):11012-7. doi: 10.1021/bi9806246.
Modular polyketide synthases (PKSs), such as the 6-deoxyerythronolide B synthase (DEBS), are multifunctional proteins that govern the synthesis of a number of clinically important natural products. The modular arrangement of active sites within these enzymes suggests the possibility of a combinatorial approach to the synthesis of novel bioactive polyketides. The efficacy of combinatorial strategies toward altering the starter unit specificity of polyketide synthases critically depends on controlling the supply of competing endogenous starter acids. Using DEBS 1-TE, a bimodular derivative of DEBS, we aimed to determine whether the beta-ketosynthase (KS) domain responsible for condensation in the first module also has the ability to prime its own biosynthesis by catalyzing the decarboxylation of methylmalonyl-CoA to produce propionyl-CoA. In contrast to earlier reports with a closely similar mini-PKS DEBS 1+TE, we have found that rigorously purified DEBS 1-TE does not catalyze the decarboxylation of methylmalonyl-CoA.
模块化聚酮合酶（PKSs），如6-脱氧红霉内酯B合酶（DEBS），是调控多种具有重要临床意义的天然产物合成的多功能蛋白质。这些酶中活性位点的模块化排列表明，有可能采用组合方法来合成新型生物活性聚酮化合物。改变聚酮合酶起始单元特异性的组合策略的有效性关键取决于控制竞争性内源性起始酸的供应。我们使用DEBS 1-TE（DEBS的一种双模块衍生物），旨在确定负责第一个模块中缩合反应的β-酮硫合酶（KS）结构域是否也具有通过催化甲基丙二酰辅酶A脱羧生成丙酰辅酶A来启动自身生物合成的能力。与早期关于非常相似的小型PKS DEBS 1+TE的报道不同，我们发现经过严格纯化的DEBS 1-TE不会催化甲基丙二酰辅酶A的脱羧反应。
