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La estructura del ADN-PKcs sugiere un mecanismo alostérico que modula la reparación de la ruptura de la doble hebra

Bancinyane L Sibanda¹, Dimitri Y Chirgadze¹, David B Ascher¹

¹Department of Biochemistry, University of Cambridge, Old Addenbrooke's Site, 80 Tennis Court Road, Cambridge CB2 1GA, UK.

Science (New York, N.Y.)

|February 4, 2017

Resumen

La subunidad catalítica de la proteína quinasa dependiente del ADN (ADN-PKcs) repara las rupturas de doble cadena del ADN. Su estructura revela un mecanismo de activación alostérica y competencia con BRCA1, que influye en la elección de la vía de reparación del ADN.

Área de la Ciencia:

Biología molecular
Biología estructural
La bioquímica

Sus antecedentes:

La subunidad catalítica de la proteína quinasa dependiente del ADN (ADN-PKcs) es crucial para la reparación del ADN no homólogo.
NHEJ repara las rupturas de doble cadena de ADN, previniendo la apoptosis y el cáncer.
La desregulación de las vías de reparación del ADN está implicada en la tumorigénesis.

Objetivo del estudio:

Para dilucidar la estructura del ADN-PKcs en complejo con Ku80.
Para comprender la regulación alostérica de la actividad de la kinasa de ADN-PKcs.
Para investigar la interacción entre el ADN-PKcs, Ku80 y BRCA1 en la selección de la vía de reparación del ADN.

Principales métodos:

Cristalografía de rayos X con una resolución de 4.3 angstroms.
Análisis estructural del complejo 4128-aminoácido DNA-PKcs-Ku80.
Análisis comparativo de las unidades estructurales y de la accesibilidad del sitio activo.

Principales resultados:

La estructura revela tres unidades distintas: N-terminal, Cuna circular y Cabeza.
Las variaciones conformacionales se correlacionan con la accesibilidad del sitio activo de la quinasa, lo que sugiere una activación alostérica.
La unión del péptido C-terminal Ku80 cerca del sitio del BRCA1 implica competencia, influyendo en la elección de la vía.

Conclusiones:

La estructura resuelta proporciona información sobre la regulación y la función del ADN-PKcs en NHEJ.
Los mecanismos alostéricos gobiernan la activación de la kinasa del ADN-PKcs.
La competencia entre Ku80 y BRCA1 en el sitio de unión ADN-PKcs dicta la elección entre NHEJ y vías de reparación de recombinación homólogas.

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