, 2004). Since we showed that ComX regulated cinA expression increases dramatically in response to CSP, we investigated the role of CinA in genetic transformation by assessing the TF of S. mutans FK866 solubility dmso UA159 wild type and SmuCinA in the presence and absence of synthetic CSP. Relative to wild type, the natural transformability and TF with added CSP of SmuCinA was significantly decreased by 15- and 74-fold, respectively (P < 0.001) (Fig. 3). Since we showed that cinA was co-transcribed with recA under competence-inducing conditions, and because deletion of cinA caused polar effects on recA expression, we constructed a CinA complemented strain SmuCinA+pCinAHis

that was used in TF assays to validate CinA’s role in genetic transformation.

In the CinA complemented strain, although transformability was drastically increased relative to the CinA-deficient mutant, TF was not restored to wild type levels as observed under no-CSP and plus-CSP conditions (Fig. 3). More specifically, an approximate 5-fold decrease in TF was observed in the SmuCinA+pCinAHis strain relative to UA159 in the presence or absence of CSP (P < 0.001) (Fig. 3). Despite polar effects on recA as judged by expression analysis using SmuCinA and UA159 strains, partial restoration of DNA Damage inhibitor the competence phenotype by the CinA complemented strain demonstrates a clear role for cinA in genetic transformation in S. mutans. Carteolol HCl However, we cannot ignore the possible contribution of recA to the transformation results we observed. RecA is a major component of the bacterial homologous recombination apparatus and is essential for the transformation of both plasmid and chromosomal DNA in S. pneumoniae (Mortier-Barriere et al., 1998). Our inability to fully complement the CinA deficiency was likely caused by diminished recA expression in the SmuCinA mutant. Recently Mashburn-Warren et al. (2010) showed that S. mutans ComR serves as the proximal regulator of ComX, that ComR is activated by exogenous XIP. Hence, it is likely that the ComRS system also regulates cinA transcription

by activating ComX. Examination of other two component signaling systems in S. mutans suggests that in addition to the CSP-activated ComDE, other systems including RelRS, CiaRH, and VicRK also modulate ComX activity [(Ahn et al., 2006), unpublished data], thus affecting expression of cinA. While here we focused on understanding ComX-mediated effects on cinA transcription and function, the regulatory roles of these other systems on ComX and CinA also warrant additional experimentation. Since cinA was up-regulated in the presence of CSP, and CSP was shown to modulate cell death via activity of ComX (Perry et al., 2009; Lemme et al., 2011), we hypothesized that CinA participated in CSP-induced cell lysis. To test this, we first monitored the growth of S.