Transcriptional analysis of the bglP gene from Streptococcus mutans

To localize the promoter activity associated with the bglP locus, a series of transcriptional lacZ gene fusions was formed on a reporter shuttle vector using various DNA fragments from the bglP promoter region. Subsequent beta-galactosidase assays in S. mutans localized the bglP promoter region and identified putative -35 and -10 promoter elements. Primer extension analysis identified the bglP transcriptional start site. In addition, a terminated bglP transcript formed by transcriptional termination was identified via transcript mapping experiments.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 bglP transcript.Beta-glucosides are carbohydrates that contain a core glucose molecule that has an R-group attached to the C-l carbon. The R-group may be another carbohydrate or various other molecules such as amino acids or ringed compounds. Beta-glucosides are commonly found in nature in various sources such as tuberous vegetables. These compounds are generally broken down for the glucose molecule, while the R-group may or may not be metabolized. Beta-glucoside utilization systems have been described in several bacteria including Escherichia coli [1], Erwinia chrysanthemi [2], Clostridium longisporum [3], Lactobacillus plantarium [4], Bacillus subtilis [5,6], and Streptococcus mutans [7]. All of these organisms rely on the phosphoenolpyruvate-dependent phosphotransferase system (PTS) [8] for the transport of beta-glucosides into the bacterial cell.It has been previously shown that the S. mutans bglP gene encodes a beta-glucoside-specific enzyme II of the PTS [7]. An additional open reading frame adjacent to bglP has been isolated, sequenced, and examined for a possible regulatory function [9]. The open reading frame encodes a putative regulatory protein of the BglG family of transcriptional antiterminators [10]. Antiterminator