Lopanik Nicole B, Shields Jennifer A, Buchholz Tonia J, Rath Christopher M, Hothersall Joanne, Haygood Margo G, Håkansson Kristina, Thomas Christopher M, Sherman David H
Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
Chem Biol. 2008 Nov 24;15(11):1175-86. doi: 10.1016/j.chembiol.2008.09.013.
The putative modular polyketide synthase (PKS) that prescribes biosynthesis of the bryostatin natural products from the uncultured bacterial symbiont of the marine bryozoan Bugula neritina possesses a discrete open reading frame (ORF) (bryP) that encodes a protein containing tandem acyltransferase (AT) domains upstream of the PKS ORFs. BryP is hypothesized to catalyze in trans acylation of the PKS modules for polyketide chain elongation. To verify conservation of function, bryP was introduced into AT-deletion mutant strains of a heterologous host containing a PKS cluster with similar architecture, and polyketide production was partially rescued. Biochemical characterization demonstrated that BryP catalyzes selective malonyl-CoA acylation of native and heterologous acyl carrier proteins and complete PKS modules in vitro. The results support the hypothesis that BryP loads malonyl-CoA onto Bry PKS modules, and provide the first biochemical evidence of the functionality of the bry cluster.
假定的模块化聚酮合酶（PKS）负责从海洋苔藓虫类动物内肛苔虫未培养的细菌共生体中生物合成苔藓抑素天然产物，它拥有一个离散的开放阅读框（ORF）（bryP），该阅读框编码一种蛋白质，该蛋白质在PKS的ORF上游含有串联酰基转移酶（AT）结构域。据推测，BryP催化PKS模块的反式酰化作用以实现聚酮链的延长。为了验证功能的保守性，将bryP导入含有具有相似结构的PKS簇的异源宿主的AT缺失突变菌株中，聚酮化合物的产生得到了部分挽救。生化特性表明，BryP在体外催化天然和异源酰基载体蛋白以及完整PKS模块的选择性丙二酰辅酶A酰化作用。这些结果支持了BryP将丙二酰辅酶A加载到Bry PKS模块上的假设，并提供了bry簇功能的首个生化证据。
