Mechanisms of Sugar Aminotransferase-like Enzymes to Synthesize Stereoisomers of Non-proteinogenic Amino Acids in Natural Product Biosynthesis
Mechanisms of Sugar Aminotransferase-like Enzymes to Synthesize Stereoisomers of Non-proteinogenic Amino Acids in Natural Product Biosynthesis
复制标题
DOI：
10.1021/acschembio.2c00823
复制
发表时间：
2023-01-20
影响因子：
4
通讯作者：
Nishiyama，Makoto
中科院分区：
文献类型：
--
作者：
Kurosawa，Sumire;Okamura，Hironori;Nishiyama，Makoto
（2，6）-二氨基-（5，7）-二羟基庚酸（DADH），一种非蛋白质氨基酸，转化为含1-氮杂双环[3.1.0]己烷环的氨基酸，随后掺入纤维素霉素和vazabitide A中。本研究表明，糖氨基转移酶样酶Fic 25和Vzb 9，具有较高的氨基酸序列的同一性（56%），相互合成的立体异构体的DADH（6S）和（6 R）构型，分别。具有PLP-（6S）-N2-乙酰基-DADH加合物的Fic 25复合物的晶体结构表明Asn 45和Gln 197（Vzb 9中的Asn 205和Ala 53）位于影响所合成的DADH的立体化学的位置。一项建模研究表明，Fic 25和Vzb 9之间的氨基酸取代允许酶与底物结合，在DADH分子的C5-C7部分几乎旋转180°，伴随着C1-C4部分的伴随位移。为了支持该结果，Fic 25和Vzb 9中两个相应残基的替换分别增加了（6 R）和（6S）立体选择性。DADH的C6处的不同立体化学导致1-氮杂双环[3.1.0]己烷环的氮丙啶部分的不同立体化学/取向，其在纤维素霉素和伐扎比特A之间的生物活性中起关键作用。一项基因分析表明，Fic 25和Vzb 9从糖氨基转移酶进化而来，产生了不寻常的构建模块，用于扩大次级代谢产物的结构多样性。
(2,6)-Diamino-(5,7)-dihydroxyheptanoic acid (DADH), a non-proteinogenic amino acid, is converted to 1-azabicyclo[3.1.0]hexane ring-containing amino acids that are subsequently incorporated into ficellomycin and vazabitide A. The present study revealed that the sugar aminotransferase-like enzymes Fic25 and Vzb9, with a high amino acid sequence identity (56%) to each other, synthesized stereoisomers of DADH with (6S) and (6R) configurations, respectively. The crystal structure of the Fic25 complex with a PLP-(6S)–N2-acetyl-DADH adduct indicated that Asn45 and Gln197 (Asn205 and Ala53 in Vzb9) were located at positions that affected the stereochemistry of DADH being synthesized. A modeling study suggested that amino acid substitutions between Fic25 and Vzb9 allowed the enzymes to bind to the substrate with almost 180° rotation in the C5–C7 portions of the DADH molecules, accompanied by a concomitant shift in their C1–C4 portions. In support of this result, the replacement of two corresponding residues in Fic25 and Vzb9 increased (6R) and (6S) stereoselectivities, respectively. The different stereochemistry at C6 of DADH resulted in a different stereochemistry/orientation of the aziridine portion of the 1-azabicyclo[3.1.0]hexane ring, which plays a crucial role in biological activity, between ficellomycin and vazabitide A. A phylogenic analysis suggested that Fic25 and Vzb9 evolved from sugar aminotransferases to produce unusual building blocks for expanding the structural diversity of secondary metabolites.