The hmsT 3' untranslated region mediates c-di-GMP metabolism and biofilm formation in Yersinia pestis.

Yersinia pestis, the cause of plague, forms a biofilm in the proventriculus of its flea vector to enhance transmission. Biofilm formation in Y. pestis is regulated by the intracellular levels of cyclic diguanylate (c-di-GMP). In this study, we investigated the role of the 3 untranslated region (3UTR) in hmsT mRNA, a transcript that encodes a diguanylate cyclase that stimulates biofilm formation in Y. pestis by synthesizing the second messenger c-di-GMP. Deletion of the 3UTR increased the half-life of hmsT mRNA, thereby upregulating c-di-GMP levels and biofilm formation. Our findings indicate that multiple regulatory sequences might be present in the hmsT 3UTR that function together to mediate mRNA turnover. We also found that polynucleotide phosphorylase is partially responsible for hmsT 3UTR-mediated mRNA decay. In addition, the hmsT 3UTR strongly repressed gene expression at 37 degrees C and 26 degrees C, but affected gene expression only slightly at 21 degrees C. Our findings suggest that the 3UTR might be involved in precise and rapid regulation of hmsT expression, allowing Y. pestis to fine-tune c-di-GMP synthesis and consequently regulate biofilm production to adapt to the changing host environment.