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Estructura enzimática con dos sitios catalíticos para la selección de sustrato por doble tamiz
O Nureki1, D G Vassylyev, M Tateno
1Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan.
Science (New York, N.Y.)
|May 9, 1998
Resumen
La edición enzimática asegura una transferencia precisa de la información genética. La isoleucil-tRNA sintetasa utiliza un mecanismo de doble criba para hidrolizar selectivamente los accesorios de aminoácidos incorrectos, manteniendo la fidelidad de la traducción.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
Sus antecedentes:
- La transferencia precisa de la información genética es crucial para la síntesis de proteínas.
- Los mecanismos de edición enzimática juegan un papel vital en el mantenimiento de la fidelidad de la traducción.
- Se sabe que la ARN sintetasa de transferencia de isoleucilo (IleRS) posee actividad de edición.
Objetivo del estudio:
- Para dilucidar la base estructural de la actividad de edición en isoleucil-transferencia de ARN sintetasa.
- Para proporcionar estructuras cristalinas de alta resolución de la enzima en complejo con sus sustratos.
Principales métodos:
- Se empleó cristalografía de rayos X para determinar la estructura de la enzima.
- Las estructuras cristalinas se resolvieron a una resolución de 2,5 angstroms.
- Se analizaron los complejos enzimáticos con L-isoleucina y L-valina.
Principales resultados:
- Las estructuras cristalinas revelan un mecanismo de "doble criba" para la selección del sustrato.
- El primer tamiz se encuentra en el dominio de aminoacilación (pliegue de Rossmann).
- El segundo, el tamiz de edición, está situado en un dominio de barril beta globular distinto.
Conclusiones:
- La estructura de doble dominio de IleRS facilita un proceso de selección de sustrato en dos pasos.
- Este mecanismo estructural explica la capacidad de la enzima para discriminar entre aminoácidos cognados y no cognados.
- Los hallazgos proporcionan información sobre el mantenimiento de la transferencia de información genética de alta fidelidad durante la traducción.
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