Regulation of PTSBio by transcriptional repressor NigR

In this study we analyzed the transcriptional regulation of the operon (OBio) encoding the PTSBio and showed that it was repressed by NigR, a LacI-like transcriptional regulator. To elucidate the role of NigR in regulation of S. mutans carbohydrate transporters we performed full genome expression microarrays using custom Affymetrix chip. Expression microarray analysis was performed with ΔnigR grown in CDM supplemented with glucose and compared to that of WT grown under identical conditions. Deletion of the nigR gene did not exert broad transcription changes in S. mutans under tested conditions. OBio was the only operon that was significantly upregulated in the ΔnigR strain (Supplemental Table 1). This data confirmed that NigR is the repressor of OBio and that OBio is its only PTS target under tested condition. Streptococcus mutans UA159 wild-type cells and ΔnigR strains were grown in a chemically-defined medium supplemented with glucose until the mid-log phase. The transcriptional profile of the whole genome was examined with microarray.