rnc基因调控变形链球菌蔗糖依赖性黏附能力的机制研究

Regulation mechanism of rnc gene on sucrose-dependent cell adherence of Streptococcus mutans

目的:探讨rnc基因缺失后变形链球菌蔗糖依赖性黏附能力的改变,并分析其在细菌生物膜早期黏附中的作用机制。方法:采用PCR连接诱变法构建变形链球菌rnc基因缺失突变株,通过蔗糖依赖性黏附实验对比变形链球菌rnc基因缺失突变菌株和标准株UA159的黏附能力;RT-q PCR验证rnc缺失后变形链球菌蔗糖依赖性黏附相关基因的表达水平差异。结果:rnc缺失突变株蔗糖依赖性黏附能力及生物膜成膜能力较变形链球菌UA159降低;rnc缺失后蔗糖依赖性黏附相关调控基因gbp B,gtf B,gtf D,dex A显著上调,而gbp C、gbp D显著下调。结论:rnc缺失影响蔗糖依赖性黏附相关基因的表达,降低了变形链球菌蔗糖依赖性黏附能力,影响其致龋性。

Objective： The aim of the current study was to verify the involvement of rnc gene in the sucrose-dependent cell adherence of Streptococcus mutans（ S. mutans）,and to analyze its functional roles. Methods： An rnc knockout mutant（ Smurnc） was constructed by PCR ligation mutagenesis in S. mutans UA159. Sucrose-dependent cell adherence assay was performed to compare the adhesion ability of Streptococcus mutans UA159 and Smurnc. RT-q PCR was used to analyze the effects of rnc knockout on the expression of the sucrose-dependent cell adherence related genes at the transcriptional level.Results： The sucrose-dependent adhesion and the biofilm formation decreased in Smurnc. Expression of the sucrose-dependent cell adherence related genes gbp B,gtf B,gtf D and dex A had been significantly upregulated,gbp C and gbp D of the rnc knockout mutant had been significantly downregulated. Conclusion： Based on these findings,it was established that rnc depletion impaired sucrose-dependent adherence of S. mutans UA159. rnc gene may regulate the expression of sucrose-dependent adherence related genes and involve in the cariogenecity of Strptococcus mutans.