Wang Lei, Xie Jinru, Wang Qing, Wang Penghe, Hu Xinxin, Nie Tongying, Hou Lei, Yang Xinyi, Wang Xiukun, You Xuefu, Li Congran
Beijing Key Laboratory of Technology and Application for Anti-Infective New Drugs Research and Development, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
Division for Medicinal Microorganisms Related Strains, CAMS Collection Center of Pathogenic Microorganisms, Beijing 100050, China.
Int J Mol Sci. 2025 Apr 25;26(9):4110. doi: 10.3390/ijms26094110.
Methicillin-resistant (MRSA) infection is a serious clinical threat, and D-Serine (D-Ser) showed significant sensitization effects on β-lactams against MRSA in our previous study. Quantitative PCR analysis found the elevated expression of the operon with D-Ser combination, which is responsible for wall teichoic acid (WTA) modification involving D-Alanine (D-Ala). This study aims to verify the effect of D-Ser on WTA modification through the pathway and explore the related effects on bacteria. The DltA and DltC were recombined, and enzyme kinetic evaluations with different D-amino acids were then conducted; it was found that D-Ser is the second-best substrate for DltA (just after D-Ala), no matter whether DltC is present or not. D-Ser treatment also lowered WTA generation as demonstrated by WTA phosphate quantification and native-PAGE electrophoresis, increased the susceptibility of to polymyxins, and elevated the mouse survival rate in the MRSA intraperitoneal infection model without affecting the bacterial loads in the main organs, indicating possible effects of D-Ser on MRSA virulence through WTA modification. In conclusion, the current study provided evidence for D-Ser modification of WTA via the pathway, and its possible involvement in D-Ser sensitization deserves further investigation.
耐甲氧西林金黄色葡萄球菌（MRSA）感染是一种严重的临床威胁，在我们之前的研究中，D-丝氨酸（D-Ser）对β-内酰胺类药物抗MRSA显示出显著的增敏作用。定量PCR分析发现，与D-Ser联合使用时，负责壁磷壁酸（WTA）修饰（涉及D-丙氨酸（D-Ala））的操纵子表达升高。本研究旨在通过该途径验证D-Ser对WTA修饰的作用，并探索其对细菌的相关影响。将DltA和DltC重组，然后用不同的D-氨基酸进行酶动力学评估；结果发现，无论DltC是否存在，D-Ser都是DltA的第二最佳底物（仅次于D-Ala）。WTA磷酸定量和非变性聚丙烯酰胺凝胶电泳表明，D-Ser处理还降低了WTA的生成，增加了对多粘菌素的敏感性，并提高了MRSA腹腔感染模型中小鼠的存活率，且不影响主要器官中的细菌载量，这表明D-Ser可能通过WTA修饰对MRSA毒力产生影响。总之，本研究为D-Ser通过该途径修饰WTA提供了证据，其在D-Ser增敏作用中的可能参与值得进一步研究。
