A dynamic competition between release factor 2 and the tRNASec decoding UGA at the recoding site of Escherichia coli formate dehydrogenase H
AUTOR(ES)
Mansell, John B.
FONTE
Oxford University Press
RESUMO
Factors affecting competition between termination and elongation in vivo during translation of the fdhF selenocysteine recoding site (UGA) were studied with wild-type and modified fdhF sequences. Altering sequences surrounding the recoding site UGA without affecting RNA secondary structure indicated that the kinetics of stop signal decoding have a significant influence on selenocysteine incorporation efficiency. The UGA in the wild-type fdhF sequence remains ‘visible’ to the factor and forms a site-directed cross-link when mRNA stem–loop secondary structure is absent, but not when it is present. The timing of the secondary structure unfolding during translation may be a critical feature of competition between release factor 2 and tRNASec for decoding UGA. Increasing the cellular concentration of either of these decoding molecules for termination or selenocysteine incorporation showed that they were able to compete for UGA by a kinetic competition that is dynamic and dependent on the Escherichia coli growth rate. The tRNASec-mediated decoding can compete more effectively for the UGA recoding site at lower growth rates, consistent with anaerobic induction of fdhF expression.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=125778Documentos Relacionados
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