Structural and Functional Studies of Pavine N-Methyltransferase from Thalictrum flavum Reveal Novel Insights into Substrate Recognition and Catalytic Mechanism
作者:Miguel A. Torres、Elesha Hoffarth、Luiz Eugenio、Julia Savtchouk、Xue Chen、Jeremy S. Morris、Peter J. Facchini、Kenneth K.-S. Ng
DOI:10.1074/jbc.m116.747261
日期:2016.11
nitrogen atom of the alkaloid acceptor decreased enzyme activity without disrupting the structure of the protein. The binding site for THP provides a framework for understanding substrate specificity amongst numerous NMTs involved in the biosynthesis of BIAs and other specialized metabolites. This information will facilitate metabolic engineering efforts aimed at producing medicinally important compounds
苄基异喹啉生物碱(BIA)可在多种植物中生产,并且包括许多常见的镇痛药,镇咳药和抗癌药。独特的S-腺苷甲硫氨酸(SAM)依赖性N-甲基转移酶(NMT)家族的几个成员在BIA生物合成中起着关键作用,但是参与BIA代谢的NMT尚不知道底物识别和催化的分子基础。为了解决这个问题,使用硒代蛋氨酸取代的蛋白质(dmin = 2.8 A)解决了黄藻中牛NMT(PavNMT)的晶体结构问题。确定了天然蛋白(dmin = 2.0 A)以及与SAM的二元复合物(dmin = 2.3 A)或反应产物S-腺苷同型半胱氨酸(SAH)(dmin = 1.6 A)的其他结构。SAH和两个四氢罂粟碱(THP,一个是S构象异构体,另一个是R构型(dmin = 1.8 A)揭示了底物识别的关键特征。PavNMT将外消旋THP转化为月桂苷,但该酶显示出优先选择(+/-)-牛筋和(S)-网状尿素作为底物。这些结构表明在活性位点