On-Line Polyketide Cyclization into Diverse Medium-Sized Lactones by a Specialized Ketosynthase Domain
作者:Srividhya Sundaram、Hak Joong Kim、Ruth Bauer、Tawatchai Thongkongkaew、Daniel Heine、Christian Hertweck
DOI:10.1002/anie.201804991
日期:2018.8.27
Ketosynthase (KS) domains of modular type I polyketide synthases (PKSs) typically catalyze the Claisen condensation of acyl and malonyl units to form linear chains. In stark contrast, the KS of the rhizoxin PKS branching module mediates a Michael addition, which sets the basis for a pharmacophoric δ‐lactone moiety. The precise role of the KS was evaluated by site‐directed mutagenesis, chemical probes
模块化I型聚酮化合物合酶(PKS)的酮合酶(KS)域通常催化酰基和丙二酰单元的Claisen缩合形成线性链。与之形成鲜明对比的是,根瘤菌素PKS分支模块的KS介导了迈克尔加成反应,这为药效基团δ-内酯部分奠定了基础。通过定点诱变,化学探针和生物转化评估了KS的确切作用。生化和动力学分析有助于剖析分支和内酯化反应,并将整个序列明确分配给KS。在体外用各种合成替代物探测可接受的底物范围时,我们发现KS可以耐受定义的酰基链长度,以产生5至7元内酯。这些结果表明,KS具有催化β分支和内酯化的功能,因此具有多功能性。