Abstract
GntR family transcription factors have been implicated in the regulation of carbohydrate transport and metabolism in many bacteria. However, the function of this transcription factor family is poorly studied in Streptococcus mutans, which is a commensal bacterium in the human oral cavity and a well-known cariogenic pathogen. One of the most important virulence traits of S. mutans is its ability to transport and metabolize carbohydrates. In this study, we identified a GntR transcription factor in S. mutans named StsR (Sugar Transporter Systems Regulator). The deletion of the stsR gene in S. mutans caused a decrease in both the formation of biofilm and the production of extracellular polysaccharides (EPS) at early stage. Global gene expression profiling revealed that the expression levels of 188 genes were changed in the stsR mutant, which could be clustered with the sugar PTS and ABC transporters. Furthermore, StsR protein was purified and its conserved DNA binding motif was determined using electrophoretic mobility shift assays (EMSA) and DNase I footprinting assays. Collectively, the results of this research indicate that StsR is an important transcription factor in S. mutans that regulates the expression of sugar transporter genes, production of EPS and formation of biofilm.
Highlights
Dental caries is a biofilm-mediated, sugar-driven, multifactorial, dynamic disease (Pitts et al, 2017)
Genes involved in the transport and metabolism of sugar in S. mutans are known to be regulated by transcription factors, sigma factor, two-component regulatory systems (TCS), and other proteins (Ajdic et al, 2002)
To identify the function of each GntR family transcription factor, we built a mutant library including each of the GntR family genes in S. mutans: S. mutans 640c, S. mutans 953c, S. mutans 1012c, S. mutans 1064c, S. mutans 1065c, S. mutans
Summary
Dental caries is a biofilm-mediated, sugar-driven, multifactorial, dynamic disease (Pitts et al, 2017). The transport and metabolism of sugar have been shown to play an important role in the regulation of EPS synthesis, biofilm formation and virulence of S. mutans (Kawada-Matsuo et al, 2016). Several genes of the PTS take part in energy and material metabolism for biofilm and the extracellular matrix, and they have been shown to significantly influence biofilm formation and EPS synthesis (Loo et al, 2003; Kawada-Matsuo et al, 2016; Zeng et al, 2017). Genes involved in the transport and metabolism of sugar in S. mutans are known to be regulated by transcription factors, sigma factor, two-component regulatory systems (TCS), and other proteins (Ajdic et al, 2002)
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