Structure-based Mechanistic Insights into Terminal Amide Synthase in Nosiheptide-Represented Thiopeptides Biosynthesis.
Structure-based Mechanistic Insights into Terminal Amide Synthase in Nosiheptide-Represented Thiopeptides Biosynthesis.
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基于结构的机制洞察那西肽代表的硫肽生物合成中的末端酰胺合酶。
DOI：
10.1038/srep12744
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发表时间：
2015-08-05
影响因子：
4.6
通讯作者：
Cao C
中科院分区：
文献类型：
--
作者：
Liu S;Guo H;Zhang T;Han L;Yao P;Zhang Y;Rong N;Yu Y;Lan W;Wang C;Ding J;Wang R;Liu W;Cao C
那西肽是硫肽家族的一个母体化合物，对多种细菌病原体表现出有效的活性。其C-末端酰胺形成由NosA催化，这是通过加工其具有丝氨酸延伸的前体肽来使某些硫肽成熟的不寻常策略。本文报道了截短的NosA 1 -111变体的晶体结构，揭示了碱性赖氨酸49（K49）、酸性谷氨酸101（E101）和柔性C-末端环NosA 112 -151是那西肽生物合成中催化末端酰胺形成的关键元件。残基K49的侧链和C-末端环通过氢键和疏水相互作用固定底物。残基E101的侧链增强H2O对甲基亚胺中间体的亲核攻击，导致Cα-N键断裂和那西肽成熟。NosA及其同源物NocA、PbtH、TpdK和BerI的序列比对以及酶促分析表明，NosA的机制研究为NosA家族成员在硫肽生物合成过程中的功能提供了一个有趣的范例。
Nosiheptide is a parent compound of thiopeptide family that exhibit potent activities against various bacterial pathogens. Its C-terminal amide formation is catalyzed by NosA, which is an unusual strategy for maturating certain thiopeptides by processing their precursor peptides featuring a serine extension. We here report the crystal structure of truncated NosA1-111 variant, revealing three key elements, including basic lysine 49 (K49), acidic glutamic acid 101 (E101) and flexible C-terminal loop NosA112-151, are crucial to the catalytic terminal amide formation in nosiheptide biosynthesis. The side-chain of residue K49 and the C-terminal loop fasten the substrate through hydrogen bonds and hydrophobic interactions. The side-chain of residue E101 enhances nucleophilic attack of H2O to the methyl imine intermediate, leading to Cα-N bond cleavage and nosiheptide maturation. The sequence alignment of NosA and its homologs NocA, PbtH, TpdK and BerI, and the enzymatic assay suggest that the mechanistic studies on NosA present an intriguing paradigm about how NosA family members function during thiopeptide biosynthesis.