7UIU

N2 sub-domain of IF2 bound to the 30S subunit in the Pseudomonas aeruginosa 70S ribosome initiation complex (focused classification and refinement)

Summary for 7UIU

• Entry DOI: 10.2210/pdb7uiu/pdb
• EMDB information: 26553
• Descriptor: Translation initiation factor IF-2 (1 entity in total)
• Functional Keywords: initiation factor 2, 70s ribosome, cryo-em, translation initiation, initiator trna, conformational changes, ribosome
• Biological source: Pseudomonas aeruginosa PAO1
• Total number of polymer chains: 1
• Total formula weight: 91049.64

Authors

Basu, R.S.,Sherman, M.B.,Gagnon, M.G. (deposition date: 2022-03-29, release date: 2022-06-22, Last modification date: 2024-02-14)

Primary citation

Basu, R.S.,Sherman, M.B.,Gagnon, M.G.
Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation.
Nat Commun, 13:3388-3388, 2022

PubMed Abstract: During translation initiation, initiation factor 2 (IF2) holds initiator transfer RNA (fMet-tRNA) in a specific orientation in the peptidyl (P) site of the ribosome. Upon subunit joining IF2 hydrolyzes GTP and, concomitant with inorganic phosphate (P) release, changes conformation facilitating fMet-tRNA 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 α-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-tRNA accommodation into the P site. Our findings provide the basis by which IF2 gates the ribosome to the elongation phase.

PubMed: 35697706
DOI: 10.1038/s41467-022-31129-2

Experimental method

ELECTRON MICROSCOPY (2.8 Å)