Tao Ye, Lei Li, Wang Shuhui, Zhang Xuemei, Yin Yibing, Zheng Yuqiang
Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders and Chongqing Key Laboratory of Pediatric Metabolism and Inflammatory Diseases, Chongqing, China.
Dujiangyan People's Hospital, Chengdu, China.
Front Microbiol. 2025 Jan 3;15:1513884. doi: 10.3389/fmicb.2024.1513884. eCollection 2024.
capsular polysaccharide (CPS) is a crucial virulence factor for this pathogenic bacterium and is partially under transcriptional control. In this study, we used electrophoretic mobility shift assays and DNA enzyme footprinting to identified the hypothetical protein SPD_0410 as a negative regulator of locus. Our results showed that the D39Δ mutant strain exhibited significantly elevated CPS levels compared to the parental strain D39s. SPD_0410 directly binds at two specific sites on the promoter. The regulatory effect of SPD_0410 on CPS was weakened after the mutation of specific binding sites in the promoter. RNAseq analysis revealed that the deletion of led to alterations in glucose metabolism. However, the altered glucose levels appeared to eliminate the regulation of CPS synthesis by SPD_0410. Deleting the gene resulted in higher invasion and phagocytic resistance of bacteria and mouse experiments confirmed that D39Δ caused more severe systemic disease than the parental strain D39s. Our results indicated that SPD_0410 negatively regulates the synthesis of capsules and can directly alter pneumococcal virulence.
荚膜多糖（CPS）是这种病原菌的关键毒力因子，且部分受转录调控。在本研究中，我们使用电泳迁移率变动分析和DNA酶足迹法确定假定蛋白SPD_0410为某基因座的负调控因子。我们的结果表明，与亲本菌株D39s相比，D39Δ突变株的CPS水平显著升高。SPD_0410直接结合在某启动子上的两个特定位点。启动子中特定位点发生突变后，SPD_0410对CPS的调控作用减弱。RNA测序分析显示，某基因的缺失导致葡萄糖代谢改变。然而，葡萄糖水平的改变似乎消除了SPD_0410对CPS合成的调控。缺失该基因导致细菌的侵袭力和吞噬抗性增强，小鼠实验证实D39Δ比亲本菌株D39s引起更严重的全身性疾病。我们的结果表明，SPD_0410负调控某荚膜的合成，并可直接改变肺炎球菌的毒力。
