Article

Lack of the Delta Subunit of RNA Polymerase Increases Virulence Related Traits of Streptococcus mutans

University of California Merced, United States of America
PLoS ONE (Impact Factor: 3.23). 05/2011; 6(5):e20075. DOI: 10.1371/journal.pone.0020075
Source: PubMed

ABSTRACT The delta subunit of the RNA polymerase, RpoE, maintains the transcriptional specificity in gram-positive bacteria. Lack of RpoE results in massive changes in the transcriptome of the human dental caries pathogen Streptococcus mutans. In this study, we analyzed traits of the ΔrpoE mutant which are important for biofilm formation and interaction with oral microorganisms and human cells and performed a global phenotypic analysis of its physiological functions. The ΔrpoE mutant showed higher self-aggregation compared to the wild type and coaggregated with other oral bacteria and Candida albicans. It formed a biofilm with a different matrix structure and an altered surface attachment. The amount of the cell surface antigens I/II SpaP and the glucosyltransferase GtfB was reduced. The ΔrpoE mutant displayed significantly stronger adhesion to human extracellular matrix components, especially to fibronectin, than the wild type. Its adhesion to human epithelial cells HEp-2 was reduced, probably due to the highly aggregated cell mass. The analysis of 1248 physiological traits using phenotype microarrays showed that the ΔrpoE mutant metabolized a wider spectrum of carbon sources than the wild type and had acquired resistance to antibiotics and inhibitory compounds with various modes of action. The reduced antigenicity, increased aggregation, adherence to fibronection, broader substrate spectrum and increased resistance to antibiotics of the ΔrpoE mutant reveal the physiological potential of S. mutans and show that some of its virulence related traits are increased.

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    • "The ability to bind human extracellular matrix (ECM) is one of the major mechanisms for streptococcal pathogenesis (Paterson and Orihuela, 2010). Because of the strong adherence of the S. mutans to the ECM components (Sklavounou and Germaine, 1980), its adherence to and invasion of host cells was tested in the current work using human epithelial cells HEp-2 as used before by Xue et al. (2011). Moreover, since many of the commensal oral streptococci produce hydrogen peroxide during aerobic growth (Carlsson et al., 1983), the free radicals stress on DNA molecule of host cells increases. "
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