Structure of the protein core of translation initiation factor 2 in apo, GTP-bound and GDP-bound forms

Translation initiation factor 2 (IF2) is involved in the early steps of bacterial protein synthesis. It promotes the stabilization of the initiator tRNA on the 30S initiation complex (IC) and triggers GTP hydrolysis upon ribosomal subunit joining. While the structure of an archaeal homologue (a/eIF5...

Full description

Saved in:
Bibliographic Details
Published in:Acta crystallographica. Section D, Biological crystallography. Biological crystallography., 2013-06, Vol.69 (6), p.925-933
Main Authors: Simonetti, Angelita, Marzi, Stefano, Fabbretti, Attilio, Hazemann, Isabelle, Jenner, Lasse, Urzhumtsev, Alexandre, Gualerzi, Claudio O., Klaholz, Bruno P.
Format: Article
Language:English
Subjects:
Activation
Bacteria
Biochemistry, Molecular Biology
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
CONFORMATIONAL CHANGES
CRYSTAL STRUCTURE
CRYSTALS
GDP
Gross Domestic Product
GTP
Guanosine Diphosphate - chemistry
Guanosine Diphosphate - metabolism
Guanosine Triphosphate - chemistry
Guanosine Triphosphate - metabolism
HISTIDINE
Hydrolysis
Life Sciences
Models, Molecular
Molecular Conformation
Prokaryotic Initiation Factor-2 - chemistry
Prokaryotic Initiation Factor-2 - metabolism
PROTEINS
Research Papers
Residues
STABILIZATION
SWITCHES
SYNTHESIS
Thermus thermophilus
Thermus thermophilus - chemistry
Thermus thermophilus - metabolism
translation initiation factor 2
Translations
X-Ray Diffraction
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Translation initiation factor 2 (IF2) is involved in the early steps of bacterial protein synthesis. It promotes the stabilization of the initiator tRNA on the 30S initiation complex (IC) and triggers GTP hydrolysis upon ribosomal subunit joining. While the structure of an archaeal homologue (a/eIF5B) is known, there are significant sequence and functional differences in eubacterial IF2, while the trimeric eukaryotic IF2 is completely unrelated. Here, the crystal structure of the apo IF2 protein core from Thermus thermophilus has been determined by MAD phasing and the structures of GTP and GDP complexes were also obtained. The IF2–GTP complex was trapped by soaking with GTP in the cryoprotectant. The structures revealed conformational changes of the protein upon nucleotide binding, in particular in the P‐loop region, which extend to the functionally relevant switch II region. The latter carries a catalytically important and conserved histidine residue which is observed in different conformations in the GTP and GDP complexes. Overall, this work provides the first crystal structure of a eubacterial IF2 and suggests that activation of GTP hydrolysis may occur by a conformational repositioning of the histidine residue.
ISSN:1399-0047
0907-4449
1399-0047
DOI:10.1107/S0907444913006422