2QN6

Structure of an archaeal heterotrimeric initiation factor 2 reveals a nucleotide state between the GTP and the GDP states


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.217 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Structure of an archaeal heterotrimeric initiation factor 2 reveals a nucleotide state between the GTP and the GDP states.

Yatime, L.Mechulam, Y.Blanquet, S.Schmitt, E.

(2007) Proc Natl Acad Sci U S A 104: 18445-18450

  • DOI: 10.1073/pnas.0706784104
  • Primary Citation of Related Structures:  
    2QMU, 2QN6

  • PubMed Abstract: 
  • Initiation of translation in eukaryotes and in archaea involves eukaryotic/archaeal initiation factor (e/aIF)1 and the heterotrimeric initiation factor e/aIF2. In its GTP-bound form, e/aIF2 provides the initiation complex with Met-tRNA(i)(Met). After recognition of the start codon by initiator tRNA, e/aIF1 leaves the complex ...

    Initiation of translation in eukaryotes and in archaea involves eukaryotic/archaeal initiation factor (e/aIF)1 and the heterotrimeric initiation factor e/aIF2. In its GTP-bound form, e/aIF2 provides the initiation complex with Met-tRNA(i)(Met). After recognition of the start codon by initiator tRNA, e/aIF1 leaves the complex. Finally, e/aIF2, now in a GDP-bound form, loses affinity for Met-tRNA(i)(Met) and dissociates from the ribosome. Here, we report a 3D structure of an aIF2 heterotrimer from the archeon Sulfolobus solfataricus obtained in the presence of GDP. Our report highlights how the two-switch regions involved in formation of the tRNA-binding site on subunit gamma exchange conformational information with alpha and beta. The zinc-binding domain of beta lies close to the guanine nucleotide and directly contacts the switch 1 region. As a result, switch 1 adopts a not yet described conformation. Moreover, unexpectedly for a GDP-bound state, switch 2 has the "ON" conformation. The stability of these conformations is accounted for by a ligand, most probably a phosphate ion, bound near the nucleotide binding site. The structure suggests that this GDP-inorganic phosphate (Pi) bound state of aIF2 may be proficient for tRNA binding. Recently, it has been proposed that dissociation of eIF2 from the initiation complex is closely coupled to that of Pi from eIF2gamma upon start codon recognition. The nucleotide state of aIF2 shown here is indicative of a similar mechanism in archaea. Finally, we consider the possibility that release of Pi takes place after e/aIF2gamma has been informed of e/aIF1 dissociation by e/aIF2beta.


    Organizational Affiliation

    Laboratoire de Biochimie, Ecole Polytechnique, Centre National de la Recherche Scientifique, F-91128 Palaiseau Cedex, France.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Translation initiation factor 2 gamma subunitA414Saccharolobus solfataricus P2Mutation(s): 0 
Gene Names: eif2gSSO0412
EC: 3.6.5.3
UniProt
Find proteins for Q980A5 (Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2))
Explore Q980A5 
Go to UniProtKB:  Q980A5
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Translation initiation factor 2 alpha subunitB93Saccharolobus solfataricus P2Mutation(s): 0 
Gene Names: eif2aaif2aSSO1050
UniProt
Find proteins for Q97Z79 (Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2))
Explore Q97Z79 
Go to UniProtKB:  Q97Z79
Protein Feature View
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Translation initiation factor 2 beta subunitC18Saccharolobus solfataricus P2Mutation(s): 0 
Gene Names: eif2baif2bSSO2381
UniProt
Find proteins for Q97W59 (Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2))
Explore Q97W59 
Go to UniProtKB:  Q97W59
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GDP
Query on GDP

Download Ideal Coordinates CCD File 
E [auth A]GUANOSINE-5'-DIPHOSPHATE
C10 H15 N5 O11 P2
QGWNDRXFNXRZMB-UUOKFMHZSA-N
 Ligand Interaction
MG
Query on MG

Download Ideal Coordinates CCD File 
D [auth A]MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.264 
  • R-Value Work: 0.217 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 122.119α = 90
b = 51.851β = 94.42
c = 98.032γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
PHASERphasing
CNSrefinement
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-11-06
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Source and taxonomy, Version format compliance