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Base estructural para la translocación por AddAB helicasa-nucleasa y su detención en χ sitios

Wojciech W Krajewski¹, Xin Fu², Martin Wilkinson²

¹1] Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK [2] CRT Discovery Laboratories, Department of Biological Sciences, Birkbeck, University of London, London WC1E 7HX, UK.

|March 28, 2014

Resumen

La reparación del ADN bacteriano se basa en las enzimas AddAB/RecBCD que reconocen la secuencia Chi para procesar las rupturas de doble cadena. Los estudios estructurales revelan cómo la unión de Chi detiene la actividad enzimática, guiando la reparación y la recombinación del ADN.

Área de la Ciencia:

Biología Molecular Biología Molecular
La bioquímica es la bioquímica.
Biología Estructural Biología estructural.

Sus antecedentes:

La recombinación homóloga en las bacterias repara las rupturas de ADN de doble cadena.
Este proceso está mediado por las helicasas nucleasas AddAB/RecBCD que están reguladas por la secuencia Chi.
El reconocimiento de Chi es crucial para iniciar la carga de RecA y la posterior reparación del ADN.

Objetivo del estudio:

Para dilucidar el mecanismo estructural de la función de la enzima AddAB.
Para entender cómo la secuencia Chi regula la actividad de AddAB.
Proporcionar información sobre las vías de reparación del ADN y de recombinación genética.

Principales métodos:

Cristalografía de rayos X del Bacillus subtilis AddAB.
Formación compleja con sustratos de ADN que contienen Chi y análogos de ATP.
Comparación estructural para inferir mecanismos funcionales.

Principales resultados:

Se obtuvieron estructuras cristalinas de AddAB unido al ADN Chi.
Se propuso un mecanismo para la translocación y desenrollamiento del ADN por AddAB.
Se explicó la unión específica de AddAB a las secuencias de Chi y la detención de la translocación inducida por Chi.

Conclusiones:

La actividad de la enzima AddAB/RecBCD está regulada con precisión por la secuencia Chi.
Las ideas estructurales explican el reconocimiento del Chi y su papel en detener el procesamiento del ADN.
Esta regulación es fundamental para la reparación del ADN y la fidelidad de la recombinación genética.

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