West China Journal of Stomatology ›› 2016, Vol. 34 ›› Issue (3): 302-306.doi: 10.7518/hxkq.2016.03.017

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

Wu Xinyu, Chen Xiaodan, Zhao Wanghong, Hou Jin, Chen Xuan   

  1. Nanfang Hospital, School of Stomatology, Southern Medical University, Guangzhou 510515, China) Supported by:The National Natural Science Foundation of China(81050035); Project of Talent Introduction in Universities of Guangdong Province (C1030636); President Foundation of Nanfang Hospital, Southern Medical University(2013B003). Correspondence: Zhao Wanghong, E-mail: zhaowh@smu.edu.com.
  • Received:2015-08-11 Revised:2016-03-05 Online:2016-06-01 Published:2016-06-01

Abstract: 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 (P<0.01) 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.

Key words: Streptococcus mutans, phosphotransferase system, ptxA gene, ptxB gene, L-ascorbate

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