Hexamer to monomer equilibrium of E. coli Hfq in solution and its impact on RNA annealing.

ABSTRACT: The bacterial Sm-like protein Hfq forms a ring-shaped homo-hexamer that is necessary for Hfq to bind nucleic acids and to act in small noncoding RNA regulation. Using semi-native gels and fluorescence anisotropy, we show that Hfq undergoes a cooperative conformational change from monomer to hexamer around 1 μM protein, which is comparable to the in vivo concentration of Hfq and above the dissociation constant of the Hfq hexamer from many RNA substrates. Above 2 μM protein, Hfq hexamers associate in high-molecular-weight complexes. Mutations that impair RNA binding to the proximal face strongly destabilize the hexamer, while the mutation R16A near the outer rim prevents hexamer association. Stopped-flow fluorescence resonance energy transfer experiments showed that Hfq subunits interact wit

SUBMITTER: Panja S 

PROVIDER: S-EPMC3303956 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature