The bottromycin epimerase BotH defines a group of atypical α/β-hydrolase-fold enzymes
The bottromycin epimerase BotH defines a group of atypical α/β-hydrolase-fold enzymes
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DOI：
10.1038/s41589-020-0569-y
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发表时间：
2020-06-29
影响因子：
14.8
通讯作者：
Koehnke, Jesko
中科院分区：
文献类型：
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作者：
Sikandar, Asfandyar;Franz, Laura;Koehnke, Jesko
d-氨基酸赋予肽多种所需的特性，但是l-氨基酸翻译后和位点特异性差向异构化成它们的d-对应物是罕见的，并且在化学上具有挑战性。 Bottromycin 是核糖体合成和翻译后修饰的肽，克服了这一挑战，并具有 d-天冬氨酸 (d-Asp) 的特征，人们认为它是在生物合成过程中自发产生的。我们已经鉴定出高度不寻常的α/β-水解酶(ABH)折叠酶BotH作为肽差向异构酶，负责在底霉素生物合成过程中l-Asp到d-Asp的翻译后差向异构化。 BotH 的生化表征与 BotH 和 BotH-底物复合物的结构相结合，使我们能够提出该反应的机制。 BotH 同源物的生物信息学分析表明，在不同的生物合成基因簇中发现了相似的 ABH 酶。这使得 BotH 成为一组非典型 ABH 酶的创始成员，这些酶可能能够对不同次级代谢物家族的非天冬氨酸立体中心进行差向异构化。BotH 是一种不寻常的 α/β-水解酶折叠酶，它通过与其他已知的肽天然产物差向异构酶不同的机制，在底霉素生物合成过程中催化天冬氨酸残基的差向异构化。
d-amino acids endow peptides with diverse, desirable properties, but the post-translational and site-specific epimerization ofl-amino acids into theird-counterparts is rare and chemically challenging. Bottromycins are ribosomally synthesized and post-translationally modified peptides that have overcome this challenge and feature ad-aspartate (d-Asp), which was proposed to arise spontaneously during biosynthesis. We have identified the highly unusual alpha/beta-hydrolase (ABH) fold enzyme BotH as a peptide epimerase responsible for the post-translational epimerization ofl-Asp tod-Asp during bottromycin biosynthesis. The biochemical characterization of BotH combined with the structures of BotH and the BotH-substrate complex allowed us to propose a mechanism for this reaction. Bioinformatic analyses of BotH homologs show that similar ABH enzymes are found in diverse biosynthetic gene clusters. This places BotH as the founding member of a group of atypical ABH enzymes that may be able to epimerize non-Asp stereocenters across different families of secondary metabolites.BotH is an unusual alpha/beta-hydrolase-fold enzyme that catalyzes epimerization of an aspartate residue during bottromycin biosynthesis via a mechanism distinct from other known peptide natural product epimerases.