Role of EIIABMan and EIIGlc in regulation of energy metabolism, biofilms, and competence in Streptococcus mutans. Streptococcus mutans

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is the major carbohydrate transport system in oral streptococci. The mannose-PTS of Streptococcus mutans, which transports mannose and glucose, is involved in carbon catabolite repression (CCR) and regulates the expression of known virulence genes. In this study, we investigated the role of EIIGlc and EIIABMan in sugar metabolism, gene regulation, biofilm formation, and competence. The results demonstrate that the inactivation of ptsG, encoding a putative EIIGlc, did not lead to major changes in sugar metabolism or affect the phenotypes of interest. However, the loss of EIIGlc was shown to have a significant impact on the proteome and to affect the expression of a known virulence factor, fructan hydrolase (fruA). JAM1, a mutant strain lacking EIIABMan, had an impaired capacity to form biofilms in the presence of glucose and displayed a decreased ability to be transformed with exogenous DNA. Also, the lactose- and cellobiose-PTSs were positively and negatively regulated by EIIABMan, respectively. Microarrays were used to investigate the profound phenotypic changes displayed by JAM1, revealing that EIIABMan of S. mutans has a key regulatory role in energy metabolism, possibly by sensing the energy levels of the cells or the carbohydrate availability and, in response, regulating the activity of transcription factors and carbohydrate transporters. Keywords: Biofilms growth & development, Energy Metabolism, Gene Expression Regulation, Bacterial Overall design: S. mutans UA159 microarrays were provided by The Institute for Genomic Research (TIGR). The microarrays consisted of 1,948 70-mer oligonucleotides representing 1,960 open reading frames. The full 70-mer complement is printed four times on the surface of each microarray slide. Additional details regarding the arrays are available at TIGR's Streptococcus mutans UA159 Genome Page A reference RNA that had been isolated from 2 liters of UA159 cells grown in BHI broth to an optical density at 600 nm of 0.5 was used in every experiment. The reference RNA was purified as above, aliquoted, and stored at -80°C. Our experimental conditions consisted of S. mutans UA159 and JAM1 grown in BHI broth and collected at the mid-exponential phase of growth (optical density at 600 nm = 0.5). Six individual Cy3- labeled cDNA samples originating from six different cultures of UA159 or JAM1 were hybridized to the arrays along with Cy5-labeled reference cDNA, generating a total of 12 slides.