RESUMO
Translation elongation factor eEF1A is a G-protein which has a crucial role in the ribosomal polypeptide elongation and possesses a number of non-translational functions. Here, we show that the A,A(∗),A' helices segment of mammalian eEF1A is dispensable for the eEF1A*eEF1Bα complex formation. The A,A(∗),A' helices region did not interact with actin; however, its removal eliminates the actin bundling activity of eEF1A, probably due to the destruction of a dimeric structure of eEF1A. The translation function of monomers and the actin-bundling function of dimers of mammalian eEF1A is suggested.
Assuntos
Sequência de Aminoácidos , Fator 1 de Elongação de Peptídeos/química , Multimerização Proteica , Deleção de Sequência , Actinas/química , Actinas/genética , Actinas/metabolismo , Animais , Fator 1 de Elongação de Peptídeos/genética , Fator 1 de Elongação de Peptídeos/metabolismo , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , CoelhosRESUMO
Eukaryotic elongation factor eEF1A transits between the GTP- and GDP-bound conformations during the ribosomal polypeptide chain elongation. eEF1A*GTP establishes a complex with the aminoacyl-tRNA in the A site of the 80S ribosome. Correct codon-anticodon recognition triggers GTP hydrolysis, with subsequent dissociation of eEF1A*GDP from the ribosome. The structures of both the 'GTP'- and 'GDP'-bound conformations of eEF1A are unknown. Thus, the eEF1A-related ribosomal mechanisms were anticipated only by analogy with the bacterial homolog EF-Tu. Here, we report the first crystal structure of the mammalian eEF1A2*GDP complex which indicates major differences in the organization of the nucleotide-binding domain and intramolecular movements of eEF1A compared to EF-Tu. Our results explain the nucleotide exchange mechanism in the mammalian eEF1A and suggest that the first step of eEF1A*GDP dissociation from the 80S ribosome is the rotation of the nucleotide-binding domain observed after GTP hydrolysis.
