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La forma activa de la ADN polimerasa V es UmuD'(2)C-RecA-ATP

Qingfei Jiang¹, Kiyonobu Karata, Roger Woodgate

¹Department of Biological Sciences, University of Southern California, University Park, Los Angeles, California 90089-2910, USA.

|July 17, 2009

Resumen

RecA* transfiere RecA-ATP a la ADN polimerasa V (pol V) para crear un mutasoma activo, lo que permite la síntesis de ADN de traslación. Este mutasoma entonces funciona independientemente de RecA*, con su actividad regulada por el intercambio RecA-ATP.

Área de la Ciencia:

Biología molecular La biología molecular.
La bioquímica es la bioquímica.
Genética La genética.

Sus antecedentes:

La mutagénesis SOS en Escherichia coli involucra la ADN polimerasa V (pol V) y los filamentos de nucleoproteína RecA (RecA*).
La composición molecular precisa del pol V activo y la función exacta de RecA* en la mutagénesis no han quedado claras.

Objetivo del estudio:

Para dilucidar la composición molecular de la forma mutagénica activa de pol V.
Definir el papel específico de RecA* en la activación del pol V para la mutagénesis SOS.

Principales métodos:

Reconstitución bioquímica del complejo pol V Mut.
Análisis estequiométrico de la transferencia RecA-ATP.
Estudios cinéticos de la actividad y desactivación de pol V Mut.

Principales resultados:

RecA* transfiere una sola molécula de RecA-ATP al pol V libre (UmuD'(2) C, formando un mutasoma activo (pol V Mut) con una composición UmuD'(2) C-RecA-ATP.
Pol V Mut cataliza la síntesis de la traslación (TLS) independientemente de RecA*.
Pol V Mut se desactiva rápidamente tras la disociación del ADN, con una desactivación más lenta y retiene RecA-ATP cuando la síntesis del ADN está ausente.

Conclusiones:

El papel principal de RecA* en la mutagénesis SOS es la transferencia estequiométrica de RecA-ATP al pol V.
Esta transferencia genera el complejo mutosomal activo esencial para la síntesis de la transleción.
La actividad de Pol V Mut está regulada por el intercambio de RecA-ATP, destacando un nuevo mecanismo para controlar la mutagénesis.

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