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

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

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Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation.

Basu, R.S.Sherman, M.B.Gagnon, M.G.

(2022) Nat Commun 13: 3388-3388

  • DOI: https://doi.org/10.1038/s41467-022-31129-2
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

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

  • Organizational Affiliation

    Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Translation initiation factor IF-2A [auth x]840Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: infBPA4744
Find proteins for Q9HV55 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore Q9HV55 
Go to UniProtKB:  Q9HV55
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9HV55
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesR01GM136936
Robert A. Welch FoundationUnited StatesH-2032-20200401

Revision History  (Full details and data files)

  • Version 1.0: 2022-06-22
    Type: Initial release
  • Version 1.1: 2022-06-29
    Changes: Database references
  • Version 1.2: 2024-02-14
    Changes: Data collection