The F-ATPase operon promoter of Streptococcus mutans is transcriptionally regulated in response to external pH

Abstract

Streptococcus mutans F-ATPase, the major component of the acid-adaptive response of the organism, is transcriptionally upregulated at low pH. Fusions of the F-ATPase promoter to chloramphenicol acetyltransferase indicated that pH-dependent expression is still observed with a short promoter that contains a domain conserved between streptococcal ATPase operons.

FIG. 1.

Slot blots of RNA prepared from S. mutans UA159 grown at steady state at pH 5 or 7. Total cellular RNA samples were serially diluted as shown and were probed with the β-subunit-specific probe.

FIG. 2.

Location of predicted motifs in the intergenic space upstream of the S. mutans GS-5 ATPase operon. Motif analysis (MEME) of the intergenic spaces was conducted as described previously (3) using the San Diego Center for Supercomputing facility (http://meme.sdsc.edu/meme/website/). The three motifs ([1], [2] and [3]) are shown with their respective positional probabilities. Plus signs indicate the presence of the predicted motif in the sense strand; negative signs indicate an antisense direction to the motif. The thick arrow indicates the positioning of the short-length promoter, and the dashed arrow indicates positioning of the full-length promoter portion of the two cat fusions (described in the text). The thin arrows indicate the position of predicted inverted DNA repeats. Double-underlined sequence indicates the −35 region, and single-underlined sequence denotes the −10 region. The transcriptional start site of the promoter is shown as a bold G (29). Nucleotide sequence information for the ATPase promoters was derived from GenBank deposits with the following accession numbers: S. mutans GS-5 (U31170); S. sanguis 10904 (AF001955); S. pyogenes M1 (AE004092) (9); S. mutans UA159 (NC004350) (1).