rnc基因调节变异链球菌环境耐受性及其机制研究  

Regulation mechanism of rnc gene on Streptococcus mutans environmental tolerance and its mechanism

作　　者：张茹 雷蕾[2] 杨英明[2] 胡涛[2] ZHANG Ru;LEI Lei;YANG Yingming;HU Tao(Department of Endodontics,School of Stomatology,Capital Medical University,Beijing 100050,China;Department of Preventive Dentistry,West China Hospital of Stomatology,Sichuan University,State Key Laboratory of Oral Diseases,Chengdu 610041,China)

机构地区：[1]首都医科大学附属北京口腔医院牙体牙髓科,北京100050 [2]四川大学华西口腔医院口腔预防科,口腔疾病研究国家重点实验室,四川成都610041

出　　处：《口腔疾病防治》2018年第8期504-507,共4页Journal of Prevention and Treatment for Stomatological Diseases

基　　金：国家自然科学基金项目(81300878,81771068);北京市自然科学基金项目(7144214);北京市医院管理局青年人才培养青苗计划项目(QML20151403)

摘　　要：目的 rnc基因敲除后,观察变异链球菌的耐酸、耐氧化、耐高渗透压性能的改变及其可能的调节机制。方法通过长链PCR连接诱变技术,构建rnc基因缺失突变株,分别对比突变菌株与野生菌株对氧化环境、酸性环境及高渗透压环境的耐受能力;采用real-time RT-PCR验证rnc缺失后变异链球菌环境耐受相关基因的转录水平表达变化。结果 rnc基因缺失后,变异链球菌的耐酸性(c2=13.464,P=0.001)及耐氧化性(c2=4.505,P=0.048)较野生菌株显著下降,但耐高渗透压性显著增加(c2=11.971,P=0.001)。环境耐受相关基因lux S与rop A的表达水平显著下调(P<0.001),分别为野生菌株的0.64倍、0.51倍;而htr A与brp A的表达水平显著上调(P<0.001),分别为野生菌株的1.56倍、1.80倍。结论 rnc基因缺失影响变异链球菌环境耐受相关基因的表达,降低了变异链球菌耐酸、耐氧化能力,增强了对高渗透压的耐受能力。Objective To study the changes of acid resistance, oxidation resistance and high osmotic pressure resistance of Streptococcus mutans after knockout of rnc gene and its possible regulatory mechanism. Methods Through PCR ligation mutagenesis, an rnc knockout mutant （Smurnc） was constructed. Acid tolerance, oxidation tolerance and high osmotic pressure tolerance were compared between Smurnc and the wild strain respectively. Real-time RT-PCR was used to verify the changes in expression of stress tolerance related genes at the transcriptional level. Results When rnc gene was knocked out, the acid tolerance （χ2=13.464, P=0.001） and oxidation tolerance （χ2=4.505, P=0.048） of Streptococcus mutans was significantly decreased, but the high osmotic pressure tolerance was significantly increased （χ2=11.971, P=0.001）. Expression of stress tolerance related genes luxS and ropA （0.64 and 0.51 times expression of the wild strain） had been significantly downregulated （P〈0.001）. Expression of htrA and brpA （1.56 and 1.80 times expression of the wild strain） had been significantly upregulated （P〈0.001）. Conclusion The deletion of rnc gene affects the expression of the environmental tolerance related genes of Streptococcus mutans, which reduces its acid resistance and oxidation resistance, and enhances its tolerance to hypertonic pressure.

关 键 词：变异链球菌 rnc基因 耐酸性 氧化应激 环境耐受性 

分 类 号：R780.2[医药卫生—口腔医学]