Fig. 5.

RT-PCR gene expression profiles of cipB and cipI, encoding the bacteriocin and immunity protein respectively, in S. mutans wild-type strain and mutants defective in the alternate sigma factor ComX and the response regulator ComE. In addition to the lack of detectable transcript in the ΔcomE mutant, both cipB and cipI have putative ComE binding sites in their promoter regions (van der Ploeg, 2005), suggesting that ComE activates transcription of these genes directly. The constitutively expressed 16SrRNA gene served as a loading control.