RNA Innovation Seminar

Abstract: Bacteria use small regulatory RNAs (sRNAs) and the RNA chaperone Hfq to regulate mRNA translation and stability, akin to miRNAs and the RISC complex in eukaryotes. The approaches to defining bacterial sRNAs and their targets have dramatically improved since the screens that first identified many of them over 20 years ago. Current tools provide a global view of Hfq-binding RNAs that suggests increasingly interwoven regulatory networks, helping cell respond appropriately to stress and host interactions. On-switches for sRNAs are primarily at the level of transcription; when transcription ceases, most of the sRNAs are used stoichiometrically, being degraded as they are used, providing an effective Off-switch for sRNA regulation. We have used genetic screens to identify novel regulators of both Hfq and the sRNAs. One of these, HqbA, binds directly to the distal face of Hfq, and competes with weakly binding RNAs for association with Hfq, suggesting it is a new quality control regulator for Hfq. Data suggests that this is a bifunctional protein, directly regulating Hfq by protein-protein interaction and regulating other processes independently of Hfq. HqbA, along with other factors, help to ensure appropriate hierarchy of sRNA function.

Keywords: mRNA translation; RNAse E; Escherichia coli.