Meneely Kathleen M, Ronnebaum Trey A, Riley Andrew P, Prisinzano Thomas E, Lamb Audrey L
Department of Molecular Biosciences, ‡Department of Chemistry, and §Department of Medicinal Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.
Biochemistry. 2016 Sep 27;55(38):5423-33. doi: 10.1021/acs.biochem.6b00735. Epub 2016 Sep 15.
Thiazolinyl imine reductases catalyze the NADPH-dependent reduction of a thiazoline to a thiazolidine, a required step in the formation of the siderophores yersiniabactin (Yersinia spp.) and pyochelin (Pseudomonas aeruginosa). These stand-alone nonribosomal peptide tailoring domains are structural homologues of sugar oxidoreductases. Two closed structures of the thiazolinyl imine reductase from Yersinia enterocolitica (Irp3) are presented here: an NADP(+)-bound structure to 1.45 Å resolution and a holo structure to 1.28 Å resolution with NADP(+) and a substrate analogue bound. Michaelis-Menten kinetics were measured using the same substrate analogue and the homologue from P. aeruginosa, PchG. The data presented here support the hypothesis that tyrosine 128 is the likely general acid residue for catalysis and also highlight the phosphopantetheine tunnel for tethering of the substrate to the nonribosomal peptide synthetase module during assembly line biosynthesis of the siderophore.
噻唑啉基亚胺还原酶催化NADPH依赖的噻唑啉向噻唑烷的还原反应，这是铁载体耶尔森菌素（耶尔森菌属）和绿脓菌素（铜绿假单胞菌）形成过程中的一个必要步骤。这些独立的非核糖体肽修饰结构域是糖氧化还原酶的结构同源物。本文展示了小肠结肠炎耶尔森菌（Irp3）的噻唑啉基亚胺还原酶的两种封闭结构：一种结合NADP(+)的结构，分辨率为1.45 Å；一种全酶结构，分辨率为1.28 Å，结合了NADP(+)和一种底物类似物。使用相同的底物类似物以及铜绿假单胞菌的同源物PchG测定了米氏动力学。本文提供的数据支持以下假设：酪氨酸128可能是催化反应的一般酸残基，同时也突出了在铁载体的装配线生物合成过程中，磷酸泛酰巯基乙胺通道用于将底物连接到非核糖体肽合成酶模块。
