| Summary: | <p>Abstract</p> <p>Background</p> <p>An open reading frame encoding a putative antiterminator protein, LicT, was identified in the genomic sequence of <it>Streptococcus mutans</it>. A potential ribonucleic antitermination (RAT) site to which the LicT protein would potentially bind has been identified immediately adjacent to this open reading frame. The <it>licT </it>gene and RAT site are both located 5' to a beta-glucoside PTS regulon previously described in <it>S. mutans </it>that is responsible for esculin utilization in the presence of glucose. It was hypothesized that antitermination is the regulatory mechanism that is responsible for the control of the <it>bglP </it>gene expression, which encodes an esculin-specific PTS enzyme II.</p> <p>Results</p> <p>To localize the promoter activity associated with the <it>bglP </it>locus, a series of transcriptional <it>lacZ </it>gene fusions was formed on a reporter shuttle vector using various DNA fragments from the <it>bglP </it>promoter region. Subsequent beta-galactosidase assays in <it>S. mutans </it>localized the <it>bglP </it>promoter region and identified putative -35 and -10 promoter elements. Primer extension analysis identified the <it>bglP </it>transcriptional start site. In addition, a terminated <it>bglP </it>transcript formed by transcriptional termination was identified via transcript mapping experiments.</p> <p>Conclusion</p> <p>The physical location of these genetic elements, the RAT site and the promoter regions, and the identification of a short terminated mRNA support the hypothesis that antitermination regulates the <it>bglP </it>transcript.</p>
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