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Las estructuras y los mutantes unidos al ADN revelan la unión al ADN basal por APE1 y la coordinación de la

C D Mol¹, T Izumi, S Mitra

¹Skaggs Institute for Chemical Biology, and the Department of Molecular Biology, La Jolla, California 92037-1027, USA.

|February 10, 2000

Resumen

La enzima humana APE1 repara el ADN girando la hélice y uniendo los sitios básicos. Los datos estructurales y de mutación revelan APE1.

Área de la Ciencia:

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

Sus antecedentes:

Los sitios apurínico/apirimídico (AP) son lesiones de ADN formadas por la descomposición espontánea o la actividad de la ADN glicosilasa.
La reparación por escisión de la base (BER, por sus siglas en inglés) es crucial para mantener la integridad genómica.
La enzima humana AP endonucleasa 1 (APE1) inicia el BER mediante la escisión del ADN en los sitios de AP.

Objetivo del estudio:

Aclarar los mecanismos estructurales por los cuales el APE1 humano reconoce y se une al ADN básico.
Para determinar el mecanismo catalítico de la escisión del ADN mediada por APE1.
Para entender cómo APE1 interactúa con los intermediarios de daño del ADN durante la reparación por escisión de la base.

Principales métodos:

Cristalografía de rayos X de APE1 humano unido al ADN básico.
Co-cristalización de APE1 con el ADN escindido y Mn2+.
Mutagénesis dirigida al sitio (sustituciones de alanina) de los principales residuos de APE1.

Principales resultados:

El APE1 humano utiliza una superficie rígida y cargada positivamente para torcer y envolver la hebra de AP-ADN.
APE1 inserta bucles en ranuras de ADN y une un sitio de AP invertido en un bolsillo que excluye la base.
Los datos estructurales y mutacionales apoyan un mecanismo catalítico testable y basado en la estructura para APE1.
APE1 está optimizado para retener el producto de ADN escindido, probablemente desplazando a las glicosilasas.

Conclusiones:

APE1 emplea una estrategia estructural única para unirse y procesar las lesiones del ADN básico.
Los hallazgos proporcionan información mecanicista sobre el papel de APE1 en la coordinación de la reparación del ADN.
La capacidad de APE1 para retener el ADN escindido sugiere un papel en la gestión de los intermediarios de reparación para una síntesis eficiente de ADN.

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