Long-range interdomain communications in eIF5B regulate GTP hydrolysis and translation initiation.
Proc Natl Acad Sci U S A
; 117(3): 1429-1437, 2020 01 21.
Article
en En
| MEDLINE
| ID: mdl-31900355
ABSTRACT
Translation initiation controls protein synthesis by regulating the delivery of the first aminoacyl-tRNA to messenger RNAs (mRNAs). In eukaryotes, initiation is sophisticated, requiring dozens of protein factors and 2 GTP-regulated steps. The GTPase eIF5B gates progression to elongation during the second GTP-regulated step. Using electron cryomicroscopy (cryo-EM), we imaged an in vitro initiation reaction which is set up with purified yeast components and designed to stall with eIF5B and a nonhydrolyzable GTP analog. A high-resolution reconstruction of a "dead-end" intermediate at 3.6 Šallowed us to visualize eIF5B in its ribosome-bound conformation. We identified a stretch of residues in eIF5B, located close to the γ-phosphate of GTP and centered around the universally conserved tyrosine 837 (Saccharomyces cerevisiae numbering), that contacts the catalytic histidine of eIF5B (H480). Site-directed mutagenesis confirmed the essential role that these residues play in regulating ribosome binding, GTP hydrolysis, and translation initiation both in vitro and in vivo. Our results illustrate how eIF5B transmits the presence of a properly delivered initiator aminoacyl-tRNA at the P site to the distant GTPase center through interdomain communications and underscore the importance of the multidomain architecture in translation factors to sense and communicate ribosomal states.
Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Iniciación de la Cadena Peptídica Traduccional
/
Factores Eucarióticos de Iniciación
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Guanosina Trifosfato
Tipo de estudio:
Prognostic_studies
Idioma:
En
Año:
2020
Tipo del documento:
Article