Effect of thiostrepton and 3'-terminal fragments of aminoacyl-tRNA on EF-Tu and ribosome-dependent GTP hydrolysis.
Biochim Biophys Acta
; 698(2): 167-72, 1982 Aug 30.
Article
em En
| MEDLINE
| ID: mdl-6127109
ABSTRACT
The effect of the antibiotics thiostrepton and micrococcin on EF-Tu-catalyzed (ribosome-dependent) GTP hydrolysis in the presence of A-Phe, C-A-Phe, or C-C-A-Phe (related to the sequence of the 3'-terminus of aminoacyl-tRNA)(System I) or by methanol ('uncoupled GTPase', System II) was investigated. In System I, thiostrepton increases the binding affinities of the effectors to the EF-Tu.GTP.70 S ribosome complex, as well as the extent of the GTP hydrolysis, while the KmGTP is virtually unchanged. Similarly, in the uncoupled system (System II) and in the absence of effectors, thiostrepton significantly increases VmaxGTP, whereas KmGTP remains unaffected. Micrococcin is without any effect in both systems. The 'uncoupled GTPase' (in System II) is also strongly inhibited by C-A-Phe. The results indicate the crucial role of the EF-Tu site which binds the aminoacylated C-C-A terminus of aminoacyl-tRNA in promoting GTP hydrolysis. It follows that the binding of the model effectors (such as C-C-A-Phe) to that site is favorably influenced by the interaction of thiostrepton with the 50 S ribosomal subunit, whereas thiostrepton, per se, does not influence the affinity of EF-Tu for GTP.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ribossomos
/
Tioestreptona
/
Aminoacil-RNA de Transferência
/
Fatores de Alongamento de Peptídeos
/
Monoéster Fosfórico Hidrolases
/
Fatores de Elongação Ligados a GTP Fosfo-Hidrolases
/
Guanosina Trifosfato
/
Antibacterianos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1982
Tipo de documento:
Article