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Literature summary extracted from

  • Dubiez, E.; Aleksandrov, A.; Lazennec-Schurdevin, C.; Mechulam, Y.; Schmitt, E.
    Identification of a second GTP-bound magnesium ion in archaeal initiation factor 2 (2015), Nucleic Acids Res., 43, 2946-2957 .
    View publication on PubMedView publication on EuropePMC

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
3.6.5.3 wild-type and mutant enzyme subunit gamma in complex with GTP, GDP, or GDP analogues, with Mg2+, X-ray diffraction structure determination and analysis at 1.3-1.94 A resolution Saccharolobus solfataricus

Protein Variants

EC Number Protein Variants Comment Organism
3.6.5.3 D19A site-directed mutagenesis, the mutation does not strongly modify the GDP binding properties of the two mutant enzyme, but reduces the GTP hydrolysis rate Saccharolobus solfataricus
3.6.5.3 D19A/H97A site-directed mutagenesis, almost inactive mutant Saccharolobus solfataricus
3.6.5.3 H97A site-directed mutagenesis, the mutation does not strongly modify the GDP binding properties of the two mutant enzyme, but reduces the GTP hydrolysis rate Saccharolobus solfataricus
3.6.5.3 additional information mutant gamma subunit structure determination and analysis, and comparison to the wild-type gamma subunit structure, GTP binding structures, overview Saccharolobus solfataricus

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
3.6.5.3 additional information
-
 additional information GTP hydrolysis kinetics of wild-type and mutant enzyme subunits Saccharolobus solfataricus

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
3.6.5.3 ribosome
-
 Saccharolobus solfataricus 5840
-

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
3.6.5.3 Mg2+ required Saccharolobus solfataricus

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
3.6.5.3 GTP + H2O Saccharolobus solfataricus GTP hydrolysis by subunit aIF2gamma GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O Saccharolobus solfataricus P2 GTP hydrolysis by subunit aIF2gamma GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O Saccharolobus solfataricus JCM 11322 GTP hydrolysis by subunit aIF2gamma GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O Saccharolobus solfataricus ATCC 35092 GTP hydrolysis by subunit aIF2gamma GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O Saccharolobus solfataricus DSM 1617 GTP hydrolysis by subunit aIF2gamma GDP + phosphate
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
3.6.5.3 Saccharolobus solfataricus Q980A5 i.e. Sulfolobus solfataricus
-
3.6.5.3 Saccharolobus solfataricus ATCC 35092 Q980A5 i.e. Sulfolobus solfataricus
-
3.6.5.3 Saccharolobus solfataricus DSM 1617 Q980A5 i.e. Sulfolobus solfataricus
-
3.6.5.3 Saccharolobus solfataricus JCM 11322 Q980A5 i.e. Sulfolobus solfataricus
-
3.6.5.3 Saccharolobus solfataricus P2 Q980A5 i.e. Sulfolobus solfataricus
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
3.6.5.3 GTP + H2O GTP hydrolysis by subunit aIF2gamma Saccharolobus solfataricus GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O aIF2 significantly hydrolyses GTP in vitro, GTP hydrolysis by aIF2 or by its isolated gamma subunit. Assay with aIF2-Met-tRNAfMet enzyme complex and GTP Saccharolobus solfataricus GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O GTP hydrolysis by subunit aIF2gamma Saccharolobus solfataricus P2 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O aIF2 significantly hydrolyses GTP in vitro, GTP hydrolysis by aIF2 or by its isolated gamma subunit. Assay with aIF2-Met-tRNAfMet enzyme complex and GTP Saccharolobus solfataricus P2 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O GTP hydrolysis by subunit aIF2gamma Saccharolobus solfataricus JCM 11322 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O aIF2 significantly hydrolyses GTP in vitro, GTP hydrolysis by aIF2 or by its isolated gamma subunit. Assay with aIF2-Met-tRNAfMet enzyme complex and GTP Saccharolobus solfataricus JCM 11322 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O GTP hydrolysis by subunit aIF2gamma Saccharolobus solfataricus ATCC 35092 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O aIF2 significantly hydrolyses GTP in vitro, GTP hydrolysis by aIF2 or by its isolated gamma subunit. Assay with aIF2-Met-tRNAfMet enzyme complex and GTP Saccharolobus solfataricus ATCC 35092 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O GTP hydrolysis by subunit aIF2gamma Saccharolobus solfataricus DSM 1617 GDP + phosphate
-
 ?
3.6.5.3 GTP + H2O aIF2 significantly hydrolyses GTP in vitro, GTP hydrolysis by aIF2 or by its isolated gamma subunit. Assay with aIF2-Met-tRNAfMet enzyme complex and GTP Saccharolobus solfataricus DSM 1617 GDP + phosphate
-
 ?

Subunits

EC Number Subunits Comment Organism
3.6.5.3 heterotrimer aIF2 is composed of three subunits, alpha, bbeta, and gamma. The gamma subunit forms the core of the heterotrimer and contains the GTP-binding pocket. alpha and beta are bound to subunit gamma but do not interact together. The gamma subunit closely resembles elongation factor EF1A Saccharolobus solfataricus

Synonyms

EC Number Synonyms Comment Organism
3.6.5.3 aIF2
-
 Saccharolobus solfataricus
3.6.5.3 aIF2-gamma
-
 Saccharolobus solfataricus
3.6.5.3 aIF2gamma
-
 Saccharolobus solfataricus
3.6.5.3 IF2
-
 Saccharolobus solfataricus
3.6.5.3 initiation factor 2
-
 Saccharolobus solfataricus
3.6.5.3 Ss-aIF2
-
 Saccharolobus solfataricus

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
3.6.5.3 65
-
 assay at Saccharolobus solfataricus

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
3.6.5.3 7.5
-
 assay at Saccharolobus solfataricus

General Information

EC Number General Information Comment Organism
3.6.5.3 additional information in its GTP-bound form, aIF2 specifically binds Met-tRNAi Met and brings it to the initiation complex. The enzyme is active in its GTP-bound form, the GDP-bound form loses affinity for Met-tRNAi Met and eventually dissociates from the initiation complex. With EF1A, productive binding of tRNA is GTP-dependent and related to the ON conformations of two regions of the G domain called switch 1 and switch 2. Structure of the ternary initiation complex aIF2-GDPNP-Met-tRNA, molecular dynamics simulations, overview. Analysis of the nucleotide-binding pocket of Ss-aIF2gamma. QM/MM free energy simulations of the catalytic reaction Saccharolobus solfataricus
3.6.5.3 physiological function archaeal translation initiation processes, like eukaryotic, involve a heterotrimeric GTPase aIF2 (eIF2) crucial for accuracy of start codon selection. Enzyme aIF2 is peculiar in that it functions on the small ribosomal subunit, whereas other translational GTPases bind the same region of the assembled ribosome in all species and likely use the sarcin-ricin loop in the large subunit for activation of GTP hydrolysis Saccharolobus solfataricus