Structural dynamics of bacterial translation initiation factor IF2

J Biol Chem. 2012 Mar 30;287(14):10922-32. doi: 10.1074/jbc.M111.333393. Epub 2012 Feb 3.

Abstract

Bacterial translation initiation factor IF2 promotes ribosomal subunit association, recruitment, and binding of fMet-tRNA to the ribosomal P-site and initiation dipeptide formation. Here, we present the solution structures of GDP-bound and apo-IF2-G2 of Bacillus stearothermophilus and provide evidence that this isolated domain binds the 50 S ribosomal subunit and hydrolyzes GTP. Differences between the free and GDP-bound structures of IF2-G2 suggest that domain reorganization within the G2-G3-C1 regions underlies the different structural requirements of IF2 during the initiation process. However, these structural signals are unlikely forwarded from IF2-G2 to the C-terminal fMet-tRNA binding domain (IF2-C2) because the connected IF2-C1 and IF2-C2 modules show completely independent mobility, indicating that the bacterial interdomain connector lacks the rigidity that was found in the archaeal IF2 homolog aIF5B.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism*
  • Geobacillus stearothermophilus*
  • Guanosine Diphosphate / metabolism
  • Guanosine Triphosphate / analogs & derivatives
  • Guanosine Triphosphate / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Prokaryotic Initiation Factor-2 / chemistry*
  • Prokaryotic Initiation Factor-2 / metabolism*
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid

Substances

  • Bacterial Proteins
  • GDPNP compound
  • Prokaryotic Initiation Factor-2
  • Guanosine Diphosphate
  • Guanosine Triphosphate

Associated data

  • PDB/2LKC
  • PDB/2LKD