Structural highlights
Function
[IF2_PSEAE] One of the essential components for the initiation of protein synthesis. Protects formylmethionyl-tRNA from spontaneous hydrolysis and promotes its binding to the 30S ribosomal subunits. Also involved in the hydrolysis of GTP during the formation of the 70S ribosomal complex.[HAMAP-Rule:MF_00100]
Publication Abstract from PubMed
During translation initiation, initiation factor 2 (IF2) holds initiator transfer RNA (fMet-tRNAi(fMet)) in a specific orientation in the peptidyl (P) site of the ribosome. Upon subunit joining IF2 hydrolyzes GTP and, concomitant with inorganic phosphate (Pi) release, changes conformation facilitating fMet-tRNAi(fMet) accommodation into the P site and transition of the 70 S ribosome initiation complex (70S-IC) to an elongation-competent ribosome. The mechanism by which IF2 separates from initiator tRNA at the end of translation initiation remains elusive. Here, we report cryo-electron microscopy (cryo-EM) structures of the 70S-IC from Pseudomonas aeruginosa bound to compact IF2-GDP and initiator tRNA. Relative to GTP-bound IF2, rotation of the switch 2 alpha-helix in the G-domain bound to GDP unlocks a cascade of large-domain movements in IF2 that propagate to the distal tRNA-binding domain C2. The C2-domain relocates 35 angstroms away from tRNA, explaining how IF2 makes way for fMet-tRNAi(fMet) accommodation into the P site. Our findings provide the basis by which IF2 gates the ribosome to the elongation phase.
Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation.,Basu RS, Sherman MB, Gagnon MG Nat Commun. 2022 Jun 13;13(1):3388. doi: 10.1038/s41467-022-31129-2. PMID:35697706[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Basu RS, Sherman MB, Gagnon MG. Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation. Nat Commun. 2022 Jun 13;13(1):3388. doi: 10.1038/s41467-022-31129-2. PMID:35697706 doi:http://dx.doi.org/10.1038/s41467-022-31129-2
