Physiological and Molecular Characterization of Genetic Competence in Streptococcus sanguinis

The ability of bacteria to assimilate free DNA from the environment is known as competence. Though many studies have focused on competence regulation in Streptococcus pneumoniae and Streptococcus gordonii, Streptococcus sanguinis has yet to be examined. Physiological characterization of competence in S. sanguinis strain SK36 and its comC mutant, JFP41, led to the genome-wide transcriptional analysis of cells induced to competence via addition of competence-stimulating peptide (CSP). A total of 128 genes were induced at least 2-fold, 74 of which were classified as either “early” or “late” based on their induction patterns. Expression patterns were verified using qRT-PCR. This study identified genes not up-regulated in S. pneumoniae or S. gordonii and lays the foundation for bioinformatic studies to identify conserved binding sites upstream from CSP-regulated genes. These results also shed light on the possible existence and identity of expected CSP exporters in S. sanguinis, which have so far eluded discovery