The csgD mRNA as a hub for signal integration via multiple small RNAs.

The transcription factor CsgD governing the production of curli fimbriae and cellulose is a key player in the complex regulatory circuit that decides whether Escherichia coli form biofilms. The csgD gene itself is tightly controlled at the level of transcription by a large array of DNA-binding proteins, but what happens after transcription is less understood. In this issue of Molecular Microbiology, Jørgensen et al. (2012), Mika et al. (2012) and Thomason et al. (2012) report on small RNAs (McaS, RprA and GcvB) that together with the RNA-chaperone Hfq regulate the mRNAs of csgD and other biofilm genes, and illustrate the burgeoning concept that the 5' region of bacterial mRNA serves as a hub for sRNA-mediated signal integration at the post-transcriptional level.