Selenocysteine insertion sequence (SECIS)-binding protein 2 alters conformational dynamics of residues involved in tRNA accommodation in 80 S ribosomes.
J Biol Chem
; 287(13): 10664-10673, 2012 Mar 23.
Article
en En
| MEDLINE
| ID: mdl-22308032
Sec-tRNA(Sec) is site-specifically delivered at defined UGA codons in selenoprotein mRNAs. This recoding event is specified by the selenocysteine insertion sequence (SECIS) element and requires the selenocysteine (Sec)-specific elongation factor, eEFSec, and the SECIS binding protein, SBP2. Sec-tRNA(Sec) is delivered to the ribosome by eEFSec-GTP, but this ternary complex is not sufficient for Sec incorporation, indicating that its access to the ribosomal A-site is regulated. SBP2 stably associates with ribosomes, and mutagenic analysis indicates that this interaction is essential for Sec incorporation. However, the ribosomal function of SBP2 has not been elucidated. To shed light on the functional relevance of the SBP2-ribosome interaction, we screened the functional centers of the 28 S rRNA in translationally competent 80 S ribosomes using selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE). We demonstrate that SBP2 specifically alters the reactivity of specific residues in Helix 89 (H89) and expansion segment 31 (ES31). These results are indicative of a conformational change in response to SBP2 binding. Based on the known functions of H89 during translation, we propose that SBP2 allows Sec incorporation by either promoting Sec-tRNA(Sec) accommodation into the peptidyltransferase center and/or by stimulating the ribosome-dependent GTPase activity of eEFSec.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ribosomas
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Biosíntesis de Proteínas
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ARN Ribosómico 28S
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Aminoacil-ARN de Transferencia
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Proteínas de Unión al ARN
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Conformación de Ácido Nucleico
Límite:
Animals
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Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2012
Tipo del documento:
Article
Pais de publicación:
Estados Unidos