变异链球菌磷酸转移酶系统ptxA、ptxB基因对细菌生长能力的影响  

Effect of ptxA and ptxB genes of phosphotransferase system on growth of Streptococcus mutans

作　　者：吴昕彧 陈晓丹[1] 赵望泓[1] 侯晋[1] 陈璇[1] 

机构地区：[1]南方医科大学南方医院.南方医科大学口腔医学院,广州510515

出　　处：《华西口腔医学杂志》2016年第3期302-306,共5页West China Journal of Stomatology

基　　金：国家自然科学基金项目(81050035);广东省高校人才引进项目(C1030636);南方医科大学南方医院院长基金项目(20-13B003)~~

摘　　要：目的研究变异链球菌(S.mutans)磷酸转移酶系统(PTS)中抗坏血酸家族ptxA、ptxB基因对细菌生长能力的影响。方法构建ptxA、ptxB和ptxAB双重基因缺陷菌株以及ptxAB功能补偿菌株。在仅以抗坏血酸作为唯一碳源时,使用实时荧光定量聚合酶链反应检测野生株中ptxA、ptxB基因的表达情况。连续监测野生株、缺陷株和补偿株的菌液OD600值,比较其生长能力。结果经过聚合酶链反应和测序鉴定,结果证明缺陷株和补偿株构建成功。在以抗坏血酸作为唯一碳源的培养基中,野生株ptxA、ptxB基因的表达量均明显增高(P<0.01)。缺陷株的生长能力较野生株有所下降,但是在补偿株中可以得到补偿。结论 ptxA、ptxB基因与S.mutans对抗坏血酸的吸收利用密切相关,缺陷株和补偿株的构建为进一步研究目的基因在S.mutans抗坏血酸代谢中的作用机制提供了理论基础。Objective This study aims to evaluate the effect of ptxA and ptxB genes, which are important genes in the L-ascorbate phosphotransferase system（PTS） of Streptococcus mutans（S. mutans）. Methods The ptxA-, ptxB-, and ptxABdouble deficient mutant as well as ptxAB-complemented strain were constructed. Quantitative real-time polymerase chain reaction analysis was performed to evaluate the expression of the target genes of wild-type S. mutans when L-ascorbate was used as the sole carbohydrate source. The OD600 values of the wild type, deficient, and complemented strains were continuously monitored, and their growth curves were constructed to compare growth capacity. Results Polymerase chain reaction and sequencing analyses suggested that deficient and complemented strains were successfully constructed. The expression levels of ptxA and ptxB significantly increased（P0.01） when L-ascorbate was used as the sole carbohydrate source. The growth capacity of the deficient mutants decreased compared with that of the wild-type strain. However, the wild-type phenotype could be restored in the complemented strain. Conclusion ptxA and ptxB genes are associated with L-ascorbate metabolism of S. mutans. The construction of deficient strains and complemented strain lay a foundation for further mechanism study on L-ascorbate metabolism in S. mutans.

关 键 词：变异链球菌 磷酸转移酶系统 ptxA基因 ptxB基因 抗坏血酸 

分 类 号：R781.1[医药卫生—口腔医学]