Hfq and its constellation of RNA

Hfq is a bacterial RNA-binding protein that participates in post-transcriptional control of gene expression by facilitating the interactions between small non-coding RNAs and their target mRNAs. In this Review, Vogel and Luisi describe the structural and functional features of this protein and discuss possible mechanisms of Hfq-mediated regulation. Hfq is an RNA-binding protein that is common to diverse bacterial lineages and has key roles in the control of gene expression. By facilitating the pairing of small RNAs with their target mRNAs, Hfq affects the translation and turnover rates of specific transcripts and contributes to complex post-transcriptional networks. These functions of Hfq can be attributed to its ring-like oligomeric architecture, which presents two non-equivalent binding surfaces that are capable of multiple interactions with RNA molecules. Distant homologues of Hfq occur in archaea and eukaryotes, reflecting an ancient origin for the protein family and hinting at shared functions. In this Review, we describe the salient structural and functional features of Hfq and discuss possible mechanisms by which this protein can promote RNA interactions to catalyse specific and rapid regulatory responses in vivo.