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Flexibilidad en la recombinación del ADN: estructura del núcleo catalítico de la lambda integrasa
H J Kwon1, R Tirumalai, A Landy
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston MA 02115, USA.
Science (New York, N.Y.)
|April 4, 1997
Resumen
La lambda integrasa, una recombinasa específica del sitio, realiza reordenamientos del ADN a través de un intermediario de la fosfotirosina. Su plegado proteico conservado y su sitio activo bipartito explican sus mecanismos de escisión del ADN.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
Sus antecedentes:
- La lambda integrasa es una enzima clave en la recombinación específica del sitio, que facilita los reordenamientos del ADN.
- Funciona sin entrada de energía externa, utilizando un intermediario covalente de fosfotirosina.
Objetivo del estudio:
- Para aclarar la base estructural de la actividad catalítica de la lambda integrasa.
- Para entender el mecanismo de la escisión del ADN y el intercambio de hebras.
Principales métodos:
- Se determinó la estructura cristalina de 1.9 angstroms del dominio catalítico de la integrasa.
- Analizaron el pliegue de la proteína y los residuos del sitio activo.
Principales resultados:
- Reveló un pliegue proteico conservado en diversos organismos (desde las arquebacterias hasta la levadura).
- Se identificó un sitio activo bipartito con un bucle flexible que contiene Tyr342 y una ranura básica.
- La estructura sugiere un modelo para la interacción del ADN objetivo.
Conclusiones:
- El sitio activo bipartito explica la capacidad de la enzima para realizar la escisión del ADN cis y trans.
- La estructura conservada pone de relieve la conservación evolutiva de este mecanismo de recombinación.
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