Translation initiation at non-AUG codons mediated by weakened association of eukaryotic initiation factor (eIF) 2 subunits

Translation initiation at non-AUG codons mediated by weakened association of eukaryotic initiation factor (eIF) 2 subunits

Autor Hashimoto, Nilce Naomi Autor UNIFESP Google Scholar
Carnevalli, Larissa de Souza Autor UNIFESP Google Scholar
Castilho, Beatriz Amaral de Autor UNIFESP Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Resumo The heterotrimeric eukaryotic initiation factor (eIF) 2 binds the initiator methionyl-tRNA in a GTP-dependent mode and delivers it to the 40 S ribosomal subunit. in the present study, we have identified amino acid residues in eIF2beta required for binding to eIF2gamma in yeast. Alteration of six residues in the central region of eIF2beta abolished this interaction, as determined by GST-pull down and two-hybrid assays, and leads to cell lethality. Substitution of (131)Tyr and (132)Ser by alanine residues ((YS)-Y-131), although abolishing the binding to eIF2gamma in these assays, resulted in a functional but defective protein in vivo, imparting a temperature-sensitive growth phenotype to cells. A dramatically weakened association of this mutant protein with eIF2gamma in vivo was shown by co-immunoprecipitation. the (YS)-Y-131 mutation in eIF2beta allows translation to initiate at non-AUG codons, as defined by the ability of cells carrying an initiator codon mutation in the HIS4 mRNA to grow in the absence of histidine. the combination of this mutation with the (254)Ser --> Tyr alteration, a previously isolated suppressor of initiator codon mutations which has been shown to increase the spontaneous GTP hydrolysis in the ternary complex, caused a recessive lethality, suggesting additive defects. Thus the impaired interaction of these two subunits represents a novel type of defect in eIF2 function, providing in vivo evidence that the strength of interaction between eIF2beta and eIF2gamma defines the correct usage of the AUG codon for translation initiation.
Palavra-chave eIF2 beta mutations
non-AUG recognition
subunit interaction determinants
translation initiation
Idioma Inglês
Data de publicação 2002-10-15
Publicado em Biochemical Journal. London: Portland Press, v. 367, p. 359-368, 2002.
ISSN 0264-6021 (Sherpa/Romeo, fator de impacto)
Publicador Portland Press
Extensão 359-368
Fonte http://dx.doi.org/10.1042/BJ20020556
Direito de acesso Acesso aberto Open Access
Tipo Artigo
Web of Science WOS:000178778800006
Endereço permanente http://repositorio.unifesp.br/handle/11600/27002

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