淋球菌溶解性转糖酶C体内功能的研究

Research on the Function of Lytic Transglycosylase C in Gonococcus

目的研究淋球菌溶解性转糖酶C(LtgC)的体内活性和功能,及其酸催化活性位点(Asp405),寻找新的抗淋球菌药物作用靶点。方法利用分子克隆和同源重组技术,将淋球菌体内ltgC敲除,并将潜在活性位点的405位的天冬氨酸突变为甘氨酸,对细胞形态和生长特性进行观察和比对。结果 LtgC影响淋球菌的生长和分裂,缺失突变株细胞表面粗糙、出现褶皱,405位天冬氨酸突变株有相同表型,两株突变株细胞均生长缓慢。结论 ltgC影响淋球菌表面肽聚糖的切割和分裂,405位天冬氨酸作为酸性催化的活性中心,提供质子,帮助肽聚糖发挥酶切作用,因此,溶解性转糖酶C是良好的药物作用靶位点。

Objective This research focused on the activity and function of Lytic transglycosylase C （LtgC） in gonococcus. The Asp405 was also identified as the acid catalyst responsible for cleaving the glycosidic bond. A new potential drug target was identified. Methods The ltgC was deleted and mutated in gonococcus using the technology of molecular cloning and homologus recombinant. The Asp405 mutated into glycine in ltgC was also constructed and identified. The phenotype of cell surface and abnormal septa were observed and compared with each other under electron microscope as well as by growth characteristic. Results The surface of mutates included ltgC deletion and Asp405 mutation were rough and abrasive. The mutates of ltgC caused aberrant separation and slowed down cell growth characteristics. Conclusion Lytic transglycosylase C effected on the growth and viability of bacteria. Specificly, 405 mutate blocked the whole catalytic activity of LtgC. Considering that Asp 405 is located at the activity center of LtgC, probably, it is the activity center that digests the peptidoglycan. Therefore, lytic transglycasylase C is a potential drug target.