Department for Chemistry , University of Basel , BPR 1096, Mattenstrasse 24a , Basel , Switzerland.
Structure and Function of Proteins , Helmholtz Centre for Infection Research , Inhoffenstr. 7 , 38124 , Braunschweig , Germany.
ACS Chem Biol. 2018 May 18;13(5):1333-1342. doi: 10.1021/acschembio.8b00127. Epub 2018 Apr 16.
Ergothioneine is an emerging factor in cellular redox homeostasis in bacteria, fungi, plants, and animals. Reports that ergothioneine biosynthesis may be important for the pathogenicity of bacteria and fungi raise the question as to how this pathway is regulated and whether the corresponding enzymes may be therapeutic targets. The first step in ergothioneine biosynthesis is catalyzed by the methyltransferase EgtD that converts histidine into N-α-trimethylhistidine. This report examines the kinetic, thermodynamic and structural basis for substrate, product, and inhibitor binding by EgtD from Mycobacterium smegmatis. This study reveals an unprecedented substrate binding mechanism and a fine-tuned affinity landscape as determinants for product specificity and product inhibition. Both properties are evolved features that optimize the function of EgtD in the context of cellular ergothioneine production. On the basis of these findings, we developed a series of simple histidine derivatives that inhibit methyltransferase activity at low micromolar concentrations. Crystal structures of inhibited complexes validate this structure- and mechanism-based design strategy.
麦角硫因是细菌、真菌、植物和动物细胞氧化还原动态平衡的一个新兴因素。有报道称，麦角硫因的生物合成可能对细菌和真菌的致病性很重要，这就提出了一个问题，即该途径是如何被调控的，以及相应的酶是否可能成为治疗靶点。麦角硫因生物合成的第一步是由甲基转移酶 EgtD 催化的，它将组氨酸转化为 N-α-三甲基组氨酸。本报告研究了来自耻垢分枝杆菌的 EgtD 对底物、产物和抑制剂结合的动力学、热力学和结构基础。这项研究揭示了一种前所未有的底物结合机制和精细的亲和力景观，这是决定产物特异性和产物抑制的因素。这两个特性都是进化特征，优化了 EgtD 在细胞麦角硫因产生背景下的功能。基于这些发现，我们开发了一系列简单的组氨酸衍生物，它们以低微摩尔浓度抑制甲基转移酶活性。抑制复合物的晶体结构验证了这种基于结构和机制的设计策略。
