Abstract
The complete genome sequence of Streptococcus mutans, a bacterial pathogen commonly associated with human dental caries, was published in 2002. The streamlined genome (2.03 Mb) revealed an organism that is well adapted to its obligately host-associated existence in multispecies biofilms on tooth surfaces: a dynamic environment that undergoes rapid and substantial fluctuations. However, S. mutans lacks many of the sensing systems and alternative sigma factors that bacteria often use to coordinate gene expression in response to stress and changes in their environment. Over the past 7 years, functional genomics and proteomics have enhanced our understanding of how S. mutans has integrated the stress regulon and global transcriptional regulators to coordinate responses to environmental fluctuations with modulation of virulence in a way that ensures persistence in the oral cavity and capitalizes on conditions that are favourable for the development of dental caries. Here, we highlight advances in dissection of the stress regulon of S. mutans and its intimate interrelationship with pathogenesis.
Highlights
Caries is a classic biofilm disease that develops when changes in the oral environment enhance the growth of cariogenic bacteria, which are highly efficient at converting carbohydrates to the organic acids that demineralize tooth enamel
Over the past 7 years, functional genomics and proteomics have enhanced our understanding of how S. mutans has integrated the stress regulon and global transcriptional regulators to coordinate responses to environmental fluctuations with modulation of virulence in a way that ensures persistence in the oral cavity and capitalizes on conditions that are favourable for the development of dental caries
Comparison of the proteome of mature biofilm and planktonic cells of S. mutans cells grown at neutral pH revealed that multiple proteins associated with carbon uptake and cell division were downregulated in biofilms, whereas proteins required for the development of genetic competence were upregulated (Rathsam et al, 2005a), the latter finding being consistent with the observation that the transformation efficiency of S. mutans is optimal during biofilm growth (Li et al, 2001b)
Summary
Caries is a classic biofilm disease that develops when changes in the oral environment enhance the growth of cariogenic bacteria, which are highly efficient at converting carbohydrates to the organic acids that demineralize tooth enamel. Comparison of the proteome of mature biofilm and planktonic cells of S. mutans cells grown at neutral pH revealed that multiple proteins associated with carbon uptake and cell division were downregulated in biofilms, whereas proteins required for the development of genetic competence were upregulated (Rathsam et al, 2005a), the latter finding being consistent with the observation that the transformation efficiency of S. mutans is optimal during biofilm growth (Li et al, 2001b). This observation is thought to have significance in terms of plaque ecology. The ‘sacrifice’ of a subset of cells may enable the establishment and survival of the remainder of the population
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