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El reemplazo gradual de la histona por SWR1 requiere una activación dual con la histona H2A.Z y el nucleosoma
Ed Luk1, Anand Ranjan, Peter C Fitzgerald
1Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. luked@mail.nih.gov
Cell
|November 30, 2010
Resumen
El complejo SWR1 reemplaza la histona H2A por H2A.Z en los promotores. Este estudio revela el SWR1
Área de la Ciencia:
- * Biología Molecular.
- * La epigenética.
- * Biología de la cromatina.
Sus antecedentes:
- * La variante de histona H2A.Z es crucial para la regulación del promotor eucariótico.
- * El complejo SWR1 facilita la incorporación de H2A.Z a través del intercambio de histonas dependientes del ATP.
- * El mecanismo preciso de la deposición de H2A.Z mediada por SWR1 sigue siendo incompletamente entendido.
Objetivo del estudio:
- * Para aclarar el mecanismo de la sustitución de H2A.Z por el complejo SWR1.
- * Investigar la heterogeneidad de los nucleosomas H2A.Z en las regiones promotoras.
- * Para determinar el papel de la actividad de la ATPasa SWR1 en el intercambio de histonas.
Principales métodos:
- * Ensayos bioquímicos in vitro utilizando el complejo SWR1 purificado y los nucleosomas.
- * Análisis de la composición de los nucleosomas y estequiometría de la variante histónica.
- * Caracterización de la actividad de la ATPasa SWR1 en respuesta a diferentes sustratos.
Principales resultados:
- * Los nucleosomas promotores-proximales exhiben una heterogeneidad significativa en el contenido de H2A.Z.
- * El reemplazo de H2A.Z catalizado por SWR1 ocurre paso a paso, formando nucleosomas heterotípicos y homotípicos.
- * La actividad de la ATPasa SWR1 es estimulada por los nucleosomas que contienen H2A y los dímeros libres H2A.Z-H2B, impulsando el desalojo de H2A y la deposición de H2A.Z.
Conclusiones:
- * El complejo SWR1 media el reemplazo unidireccional y escalonado de H2A.Z.
- * La heterogeneidad de los nucleosomas en el contenido de H2A.Z es una característica de las regiones proximales del promotor.
- * La interacción entre los nucleosomas que contienen H2A y los dímeros libres H2A.Z-H2B dicta la especificidad y función de SWR1 en el intercambio de histonas.
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