InterPro domain: IPR036567

This superfamily consists of ribosome hibernation promoting factors (RHFs). RHF promotes and stabilizes dimerization of 70S ribosomes by the ribosome modulation factor (RMF), leading to the formation of inactive 100S ribosomes during the stationary phase [ 1 ].

This superfamily also includes RaiA (ribosome-associated inhibitor A, also known as Protein Y (PY), YfiA, and SpotY). This is a stress-response protein that binds the ribosomal subunit interface and arrests translation by interfering with aminoacyl-tRNA binding to the ribosomal A site [ 2 ]. RaiA is also thought to counteract miscoding at the A site thus reducing translation errors [ 3 ]. The RaiA fold structurally resembles the double-stranded RNA-binding domain (dsRBD) [ 4 ] with a beta-alpha-beta(3)-alpha fold arranged into two layers with mixed sheet, where strand 3 is antiparallel to the rest.

1. Role of HPF (hibernation promoting factor) in translational activity in Escherichia coli. J. Biochem. 143, 425-33
2. Structural basis for the control of translation initiation during stress. Nat. Struct. Mol. Biol. 11, 1054-9
3. The ribosome-associated inhibitor A reduces translation errors. Biochem. Biophys. Res. Commun. 320, 354-8
4. Ribosome-associated factor Y adopts a fold resembling a double-stranded RNA binding domain scaffold. Eur. J. Biochem. 269, 5182-91