Genome-wide characterization of the SloR metalloregulome in Streptococcus mutans.
Streptococcus mutans is the primary causative agent of human dental caries, a ubiquitous infectious disease for which effective treatment strategies remain elusive. We investigated a 25-kDa SloR metalloregulatory protein in this oral pathogen, along with its target genes that contribute to cariogenesis. Previous studies have demonstrated manganese- and SloR-dependent repression of the sloABCR metal ion transport operon in S. mutans. In the present study, we demonstrate that S. mutans coordinates this repression with that of certain virulence attributes. Specifically, we noted virulence gene repression in a manganese-containing medium when SloR binds to promoter-proximal sequence palindromes on the S. mutans chromosome. We applied a genome-wide approach to elucidate the sequences to which SloR binds and to reveal additional "class I" genes that are subject to SloR- and manganese-dependent repression. These analyses identified 204 S. mutans genes that are preceded by one or more conserved palindromic SloR recognition elements (SREs). We cross-referenced these genes with those that we had identified previously as SloR and/or manganese modulated in microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) experiments. From this analysis, we identified a number of S. mutans virulence genes that are subject to transcriptional upregulation by SloR and noted that such "class II"-type regulation is dependent on direct SloR binding to promoter-distal SREs. These observations are consistent with a bifunctional role for the SloR metalloregulator and implicate it as a target for the development of therapies aimed at alleviating S. mutans-induced caries formation.
O'Rourke
Kevin P
KP
Department of Biology, Middlebury College, 276 Bicentennial Way, MBH354, Middlebury, VT 05753. spatafor@middlebury.edu.
Shaw
Jeremy D
JD
Pesesky
Mitchell W
MW
Cook
Brian T
BT
Roberts
Susanne M
SM
Bond
Jeffrey P
JP
Spatafora
Grace A
GA
D001665:Binding Sites; D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D055029:Inverted Repeat Sequences; D008345:Manganese / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000235:genetics / Q000502:physiology*; D037521:Virulence Factors / Q000096:biosynthesis*
D004269:DNA, Bacterial; D012097:Repressor Proteins; D037521:Virulence Factors; D008345:Manganese