Conformational transitions in the γ subunit of the archaeal translation initiation factor 2

Acta Crystallogr D Biol Crystallogr. 2014 Mar;70(Pt 3):658-67. doi: 10.1107/S1399004713032240. Epub 2014 Feb 15.


In eukaryotes and archaea, the heterotrimeric translation initiation factor 2 (e/aIF2) is pivotal for the delivery of methionylated initiator tRNA (Met-tRNA(i)) to the ribosome. It acts as a molecular switch that cycles between inactive (GDP-bound) and active (GTP-bound) states. Recent studies show that eIF2 can also exist in a long-lived eIF2γ-GDP-P(i) (inorganic phosphate) active state. Here, four high-resolution crystal structures of aIF2γ from Sulfolobus solfataricus are reported: aIF2γ-GDPCP (a nonhydrolyzable GTP analogue), aIF2γ-GDP-formate (in which a formate ion possibly mimics P(i)), aIF2γ-GDP and nucleotide-free aIF2γ. The structures describe the different states of aIF2γ and demonstrate the conformational transitions that take place in the aIF2γ `life cycle'.

Keywords: GTP-binding proteins; Sulfolobus solfataricus; translation initiation factor 2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / genetics
  • Crystallography, X-Ray
  • Guanosine Triphosphate / chemistry
  • Peptide Initiation Factors / chemistry*
  • Peptide Initiation Factors / genetics
  • Protein Conformation
  • Protein Subunits / chemistry*
  • Protein Subunits / genetics
  • Sulfolobus solfataricus / chemistry*
  • Sulfolobus solfataricus / genetics


  • Archaeal Proteins
  • Peptide Initiation Factors
  • Protein Subunits
  • initiation factor 2, archaeal
  • Guanosine Triphosphate

Associated data

  • PDB/4M0L
  • PDB/4M2L
  • PDB/4M4S
  • PDB/4M53