Characterization of a FourU RNA Thermometer in the 5 Untranslated Region of Autolysin Gene blyA in the Bacillus subtilis 168 Prophage SP?

RNA thermometers are noncoding RNA structures located in the 5 ' untranslated regions (UTRs) of genes that regulate gene expression through temperature-dependent conformational changes. The fourU class of RNA thermometers contains a specific motif in which four consecutive uracil nucleotides are predicted to base pair with the Shine-Dalgarno (SD) sequence in a stem. We employed a bioinformatic search to discover a fourU RNA thermometer in the 5 '-UTR of the blyA gene of the Bacillus subtilis phage SP ss c2, a bacteriophage that infects B. subtilis 168. blyA encodes an autolysin enzyme, N-acetylmuramoyl-L-alanine amidase, which is involved in the lytic life cycle of the SP ss prophage. We have biochemically validated the predicted RNA thermometer in the 5 '-UTR of the blyA gene. Our study suggests that RNA thermometers may play an underappreciated yet critical role in the lytic life cycle of bacteriophages.