PDF(Pubmed)
Abstract：
Peptidoglycan digestion by murein-degrading enzymes is a critical process in bacterial cell growth and/or cell division. The membrane-bound lytic murein transglycosylase A (MltA) is a murein-degrading enzyme; it catalyzes the cleavage of the β-1,4-glycosidic linkage between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans. Although substrate recognition and cleavage by MltA have been examined by previous structural and mutagenesis studies, the overall mechanism of MltA in conjunction with other functionally related molecules on the outer membrane of bacterial cells for peptidoglycan degradation has remained elusive. In this study, the crystal structure of MltA from the virulent human pathogen Acinetobacter baumannii is characterized and presented. The study indicated that MltA from A. baumannii forms homodimers via an extra domain which is specific to this species. Furthermore, the working mechanism of MltA with various functionally related proteins on the bacterial outer membrane was modeled based on the structural and biochemical analysis.
摘要：
在细菌细胞生长和/或细胞分裂过程中,肽聚糖的降解酶的消化是一个关键的过程。膜结合的裂解murein转糖基化酶A（MltA）是一种murein降解酶；它催化肽聚糖中N-乙酰胞壁酸和N-乙酰葡糖胺之间的β-1,4-糖苷键的裂解。尽管先前的结构和诱变研究已经检查了Mlta的底物识别和裂解，MltA与细菌细胞外膜上的其他功能相关分子一起降解肽聚糖的总体机制仍然难以捉摸。在这项研究中,对来自人致病菌鲍曼不动杆菌的MltA的晶体结构进行了表征和呈现。研究表明,来自鲍曼不动杆菌的MltA通过对该物种特异的额外结构域形成同源二聚体。此外，基于结构和生化分析，对细菌外膜上具有各种功能相关蛋白的MltA的工作机制进行了建模。
