Analysis of <i>S. mutans</i> IGR176 region.

<p>(<b>A</b>) Schematic representation of the location of the <i>fst-Sm</i>/<i>srSm</i> locus on the <i>S. mutans</i> chromosome. Arrows indicate the direction of transcription. The <i>fst-Sm</i> and <i>srSm</i> promoter sequences are indicated by P<i>_fst-Sm</i> and P<i>_srSm</i>, respectively. A predicted stem-loop bidirectional terminator is indicated between <i>srSm</i> and <i>fst-Sm</i>. Shown at the bottom are the boundaries of the intergenic region IGR176. (<b>B</b>) Nucleotide and amino acid sequences of the <i>S. mutans fst-Sm</i>/<i>srSm</i> type I TA locus located in the intergenic region IGR176 (from 211452 to 211769) of UA159 genome. The conserved APUU(A/V)GUU motif present in Fst-Sm peptide is boxed. Putative promoter sites of <i>fst-Sm</i> toxin (–35, –10) and <i>srSm</i> antitoxin (–10), ribosome binding site (RBS) of Fst-Sm toxin, and a factor-independent bidirectional terminator (double underlined) are indicated. The transcriptional start site (+1) of <i>fst-Sm</i> and <i>srSm</i> identified by 5′ RACE-PCR are indicated below the sequence. The regions encoding the DRI and DRII repeats are boxed. The primers CMT-497 and CMT-498 used in the RT-PCR experiments are underlined. (<b>C</b>) Proposed RNA:RNA interactions (in shaded regions) between <i>fst-Sm</i> mRNA and <i>srSm</i> RNA.