Binding of the 5'-Triphosphate End of mRNA to the γ-Subunit of Translation Initiation Factor 2 of the Crenarchaeon Sulfolobus solfataricus

J Mol Biol. 2015 Sep 25;427(19):3086-95. doi: 10.1016/j.jmb.2015.07.020. Epub 2015 Aug 2.


The heterotrimeric archaeal IF2 orthologue of eukaryotic translation initiation factor 2 consists of the α-subunit, β-subunit and γ-subunit. Previous studies showed that the γ-subunit of aIF2, besides its central role in Met-tRNAi binding, has an additional function: it binds to the 5'-triphosphorylated end of mRNA and protects its 5'-part from degradation. Competition studies with nucleotides and mRNA, as well as structural and kinetic analyses of aIF2γ mutants, strongly implicate the canonical GTP/GDP-binding pocket in binding to the 5'-triphosphate end of mRNAs. The biological implication of these findings is being discussed.

Keywords: GTP; a/eIF2γ; archaea; crystal structure; mRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Crystallography, X-Ray
  • Guanosine Triphosphate / metabolism
  • Molecular Docking Simulation
  • Molecular Dynamics Simulation
  • Peptide Initiation Factors / chemistry
  • Peptide Initiation Factors / metabolism*
  • Protein Subunits
  • RNA, Archaeal / chemistry
  • RNA, Archaeal / metabolism
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism*
  • Sulfolobus solfataricus / chemistry
  • Sulfolobus solfataricus / metabolism*


  • IF2 protein, archaeal
  • Peptide Initiation Factors
  • Protein Subunits
  • RNA, Archaeal
  • RNA, Messenger
  • Guanosine Triphosphate

Associated data

  • PDB/4NBS
  • PDB/4QFM
  • PDB/4QHY