Isolation and structure determination of two new nosiheptide-type compounds provide insights into the function of the cytochrome P450 oxygenase NocV in nocathiacin biosynthesis
Isolation and structure determination of two new nosiheptide-type compounds provide insights into the function of the cytochrome P450 oxygenase NocV in nocathiacin biosynthesis
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DOI：
10.1039/c9qo01328h
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发表时间：
2020-02-07
影响因子：
5.4
通讯作者：
Liu, Wen
中科院分区：
文献类型：
--
作者：
Bai, Xuebing;Guo, Heng;Liu, Wen
硫硫肽是一类富硫、核糖体合成和翻译后修饰的多肽，在治疗口腔病原体引起的疾病方面具有巨大的潜力。诺卡西酸I(NOC-I)和诺西肽(NOS)是两个结构相似的硫肽成员，具有吲哚侧环。在NOC-I的结构中，这个侧环通过形成乙醚键而进一步刚性；然而，相关的生物合成过程仍然知之甚少。在这里，我们报告了一种在NOC-I生物合成途径中独特的细胞色素P450蛋白NocV，它负责通过两个氧化步骤建立分子内醚键。这一观察结果得益于nocv基因在产生双环NOS中间体NOS1260的工程菌中的异源过表达，以及随后两个功能化产物的分离和结构鉴定。产物NOS-V1在残基Glu6的Cα处含有一个新的羟基，与另一种产物NOS-V2形成对比，在该产物中，该羟基进一步与吲哚部分的C4甲基偶联形成醚键。这些发现为NocV在NOC-I生物合成中的催化逻辑提供了见解，在此过程中，这种细胞色素P450蛋白似乎通过选择性羟化Glu6，然后氧化偶联吲哚部分，在NOS1260的两个位置上协同作用。通过醚键形成对侧环进行硬化对NOS型硫肽的抗菌性能有积极的影响，与NOS1260相比，NOC-V2对各种受试口腔病原体的活性提高就是明证。
Thiopeptides, which are a class of sulfur-rich, ribosomally synthesized and post-translationally modified peptides (RiPPs), have great potential in the treatment of diseases caused by oral pathogens. Nocathiacin I (NOC-I) and nosiheptide (NOS) are two structurally similar thiopeptide members that feature an indolic side ring. In the structure of NOC-I, this side ring is further rigidified through the formation of an ether linkage; however, the related biosynthetic process remains poorly understood. Here, we report that NocV, a cytochrome P450 protein found to be unique in the biosynthetic pathway of NOC-I, is responsible for the establishment of the intramolecular ether linkage through two oxidation steps. This observation benefited from the heterologous overexpression of the gene nocV in an engineered Streptomyces strain producing the bicyclic NOS intermediate NOS1260, and subsequent isolation and structure characterization of two functionalized products. The product NOS-V1 contains a new hydroxyl group at C alpha of the residue Glu6, in contrast with the other product NOS-V2, in which this hydroxyl group is further coupled with the C4 methyl group of the indolic moiety to form an ether linkage. These findings provide insights into the catalytic logic of NocV in the biosynthesis of NOC-I, during which this cytochrome P450 protein appears to act in tandem on two positions in NOS1260 by selectively hydroxylating Glu6 and then oxidatively coupling the indolic moiety. Rigidifying the side ring via ether bond formation has a positive impact on the antibacterial properties of NOS-type thiopeptides, evidenced by the improved activity of NOC-V2 against various tested oral pathogens compared with NOS1260.