Hfq structure, function and ligand binding

Recent studies on Hfq have provided a deeper understanding of the multiple functions of this pleiotropic post-transcriptional regulator. Insights into the mechanism of Hfq action have come from a variety of approaches. A key finding was the characterization of two RNA binding sites: the Proximal Site, which binds sRNA and mRNA; and the Distal Site, which binds poly(A) tails. Hfq was shown to interact with PAP I, PNP and RNase E, proteins that are involved in mRNA decay and in vitro , was shown to form fibres, the physiological significance of which is unknown. Fluorescence resonance energy transfer (FRET) studies directly demonstrated the role of Hfq as a chaperone that facilitates the interaction between sRNAs and target mRNAs. There are still, however, some unresolved questions.