Characterizing the SloR Binding Sequence in an IGR that Precedes the S. mutans sloR Gene by DNA Footprinting

Streptococcus mutans is a facultatively anaerobic bacterium that colonizes the human dentition and facilitates the development of dental caries. The Spatafora lab studies a 25kDa SloR protein in S. mutans, a metalloregulator... [ view full abstract ]

Streptococcus mutans is a facultatively anaerobic bacterium that colonizes the human dentition and facilitates the development of dental caries. The Spatafora lab studies a 25kDa SloR protein in S. mutans, a metalloregulator with a central role in regulating S. mutans-induced pathogenesis. The SloR protein mediates virulence gene expression, including the sloABC and sloR genes, via binding to a promoter-proximal recognition element (SRE) in the sloABC promoter. Whether SloR binds to the 184bp intergenic region (IGR) that houses the sloR promoter region has not been explored. 

Gel mobility shift assays are ongoing in our lab to elucidate SloR-IGR binding, and the experimental results support SloR binding in this region that is distal to the sloR promoter (Annie Cowan, 2018). I am using a DNA footprinting approach to identify the nucleotides to which SloR binds in the IGR. This work could elucidate differential SloR-mediated gene expression at the sloR (up-regulation) and sloABC (down-regulation) loci.  I am also introducing point mutations into two putative SloR binding sites in the IGR for expression profiling.  The AT-rich sequences at these sites have been correlated with DNA curvature, possibly contributing to SloR-mediated sloABCR expression.  

Ultimately, these experiments can provide a more thorough understanding of the SloR-DNA interaction at this and other virulence gene loci, and inform the design of a therapeutic aimed at alleviating or preventing dental caries.