title: [Effect of ptxA and ptxB genes of phosphotransferase system on growth of Streptococcus mutans].
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 ptxAB-double 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 levelsof 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.
  
  
  CONCLUSIONS
  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.
authors.forename: Wu
authors.initials: W
authors.lastname: Xinyu
authors.forename: Chen
authors.initials: C
authors.lastname: Xiaodan
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wanghong
authors.forename: Hou
authors.initials: H
authors.lastname: Jin
authors.forename: Chen
authors.initials: C
authors.lastname: Xuan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D005798:Genes, Bacterial; D010770:Phosphotransferases / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors; C073470:LysR protein, Bacteria; D010770:Phosphotransferases