Dong Hui, Hu Tingting, He Guangzheng, Lu Deren, Qi Jianxun, Dou Yanshu, Long Wei, He Xin, Ju Jiansong, Su Dan
Key Laboratory of Tianjin Radiation and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences, Peking Union Medical College, Tianjin, China.
State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Collaborative Innovation Center for Biotherapy, Chengdu, China.
Biochem Biophys Res Commun. 2018 Feb 26;497(1):139-145. doi: 10.1016/j.bbrc.2018.02.041. Epub 2018 Feb 7.
Alanine racemase (Alr) is a pyridoxal-5'-phosphate-dependent (PLP) enzyme that catalyzes a reversible racemization between the enantiomers of alanine. d-Alanine is an indispensable constituent in the biosynthesis of bacterial cell-wall peptidoglycan, and its inhibition is lethal to prokaryotes, which makes it an attractive target for designing antibacterial drugs. In this study, the molecular structure of alanine racemase from Bacillus pseudofirmus OF4 (DadX) was determined by X-ray crystallography to a resolution of 1.8 Å. The comparison of DadX with alanine racemases from other bacteria demonstrated a conserved overall fold. Enzyme kinetics analysis showed that the conserved residues at the substrate entryway and the salt bridge at the dimer interface are critical for enzyme activity. These structural and biochemical findings provide a template for future structure-based drug-development efforts targeting alanine racemases.
丙氨酸消旋酶（Alr）是一种依赖于磷酸吡哆醛（PLP）的酶，它催化丙氨酸对映体之间的可逆消旋反应。D-丙氨酸是细菌细胞壁肽聚糖生物合成中不可或缺的成分，对其抑制对原核生物具有致死性，这使其成为设计抗菌药物的一个有吸引力的靶点。在本研究中，通过X射线晶体学确定了来自类芽孢杆菌OF4（DadX）的丙氨酸消旋酶的分子结构，分辨率为1.8埃。DadX与其他细菌的丙氨酸消旋酶的比较表明其整体折叠结构保守。酶动力学分析表明，底物入口处的保守残基和二聚体界面处的盐桥对酶活性至关重要。这些结构和生化研究结果为未来针对丙氨酸消旋酶的基于结构的药物开发工作提供了一个模板。
