On the pH dependence of class-1 RF-dependent termination of mRNA translation.
J Mol Biol
; 427(9): 1848-60, 2015 May 08.
Article
en En
| MEDLINE
| ID: mdl-25619162
We have studied the pH dependence of the rate of termination of bacterial protein synthesis catalyzed by a class-1 release factor (RF1 or RF2). We used a classical quench-flow technique and a newly developed stopped-flow technique that relies on the use of fluorescently labeled peptides. We found the termination rate to increase with increasing pH and, eventually, to saturate at about 70 s(-1) with an apparent pKa value of about 7.6. From our data, we suggest that class-1 RF termination is rate limited by the chemistry of ester bond hydrolysis at low pH and by a stop-codon-dependent and pH-independent conformational change of RFs at high pH. We propose that RF-dependent termination depends on the participation of a hydroxide ion rather than a water molecule in the hydrolysis of the ester bond between the P-site tRNA and its peptide chain. We provide a simple explanation for why the rate of termination saturated at high pH in our experiments but not in those of others.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ribosomas
/
Proteínas Bacterianas
/
Biosíntesis de Proteínas
/
ARN Mensajero
/
Factores de Terminación de Péptidos
/
Codón de Terminación
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Mol Biol
Año:
2015
Tipo del documento:
Article
País de afiliación:
Suecia
Pais de publicación:
Países Bajos