Relevance of histidine-84 in the elongation factor Tu GTPase activity and in poly(Phe) synthesis: its substitution by glutamine and alanine.
FEBS Lett
; 365(2-3): 214-8, 1995 May 29.
Article
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| MEDLINE
| ID: mdl-7781781
ABSTRACT
Substitution of His-84 (-->Gln and -->Ala), a residue of the switch II region of E. coli elongation factor (EF) Tu, hardly affected the binding of GTP or GDP. The activity in poly(Phe) synthesis and GTP hydrolysis of EF-Tu H84Q were both reduced to about 35%, as compared to EF-Tu wt, whereas EF-Tu H84A was inactive in poly(Phe) synthesis but still showed a 10% residual GTPase activity. Phe-tRNAPhe exerted a similar inhibitory effect on the GTPase activity of EF-Tu wt and EF-Tu H84Q while abolishing that of EF-Tu H84A. Ribosomes enhanced the GTPase activity of EF-Tu H84Q, but not that of EF-Tu H84A, on which they even seemed to exert an inhibitory effect. The one-round GTP hydrolysis associated with the EF-TuH84Q-dependent binding of Phe-tRNAPhe to poly(U)-programmed ribosomes was less efficient than with EF-Tu wt. Kirromycin stimulated the GTPase activities of both mutants less than EF-Tu wt. The results of this work do not support a catalytic role of His-84 in the intrinsic GTPase of EF-Tu, but they emphasize the importance of its side-chain for polypeptide synthesis and GTP hydrolysis.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Péptidos
/
Factor Tu de Elongación Peptídica
/
Factores de Elongación Enlazados a GTP Fosfohidrolasas
/
Escherichia coli
/
Histidina
Idioma:
En
Revista:
FEBS Lett
Año:
1995
Tipo del documento:
Article
País de afiliación:
Francia