tRNA binding properties of eukaryotic translation initiation factor 2 from Encephalitozoon cuniculi.
Biochemistry
; 49(40): 8680-8, 2010 Oct 12.
Article
em En
| MEDLINE
| ID: mdl-20822097
ABSTRACT
A critical consequence of the initiation of translation is the setting of the reading frame for mRNA decoding. In eukaryotic and archaeal cells, heterotrimeric initiation factor e/aIF2, in its GTP form, specifically binds Met-tRNA(i)(Met) throughout the translation initiation process. After start codon recognition, the factor, in its GDP-bound form, loses affinity for Met-tRNA(i)(Met) and eventually dissociates from the initiation complex. The role of each aIF2 subunit in tRNA binding has been extensively studied in archaeal systems. The isolated archaeal γ subunit is able to bind tRNA, but the α subunit is required for strong binding. Until now, difficulties during purification have hampered the study of the role of each of the three subunits of eukaryotic eIF2 in specific binding of the initiator tRNA. Here, we have produced the three subunits of eIF2 from Encephalitozoon cuniculi, isolated or assembled into heterodimers or into the full heterotrimer. Using assays following protection of Met-tRNA(i)(Met) against deacylation, we show that the eukaryotic γ subunit is able to bind by itself the initiator tRNA. However, the two peripheral α and ß subunits are required for strong binding and contribute equally to tRNA binding affinity. The core domains of α and ß probably act indirectly by stabilizing the tRNA binding site on the γ subunit. These results, together with those previously obtained with archaeal aIF2 and yeast eIF2, show species-specific distributions of the roles of the peripheral subunits of e/aIF2 in tRNA binding.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
RNA Fúngico
/
Proteínas Fúngicas
/
RNA de Transferência de Metionina
/
Fator de Iniciação 2 em Eucariotos
/
Encephalitozoon cuniculi
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
França