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La estructura cristalina del módulo de ubicuidad PRC1 unido al nucleosoma

Robert K McGinty¹, Ryan C Henrici², Song Tan¹

¹Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.

|October 31, 2014

Resumen

El Complejo Represivo Polycomb 1 (PRC1) utiliza su complejo enzimático E3-E2 para ubiquitalizar la histona H2A. La estructura cristalina revela cómo PRC1 reconoce sustratos nucleosómicos a través de interacciones distintas del sitio catalítico.

Área de la Ciencia:

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

Sus antecedentes:

Las proteínas del grupo de policombos (PcG) son reguladores epigenéticos cruciales.
El complejo PRC1 ubicuita la histona H2A Lys119, afectando la expresión génica.
El mecanismo de reconocimiento de nucleosomas por PRC1 sigue siendo elusivo.

Objetivo del estudio:

Para dilucidar el mecanismo molecular del reconocimiento del sustrato del nucleosoma por PRC1.1.
Determinar la base estructural de la actividad de ubicuidad de PRC1.

Principales métodos:

Cristalografía de rayos X con rayos X.
Ensayos bioquímicos (implicados)

Principales resultados:

Estructura cristalina del complejo humano Ring1B-Bmi1-UbcH5c E3-E2 unido a una partícula del núcleo del nucleosoma.
Identificación del reconocimiento de sustratos a través de interacciones con múltiples superficies de nucleosomas.
La revelación de un nuevo papel para la enzima E2 (UbcH5c) en la unión al sustrato.

Conclusiones:

PRC1 logra la especificidad del sustrato a través de interacciones distantes del sitio catalítico.
La enzima E2 juega un papel inesperado en el reconocimiento de nucleosomas.
Las ideas estructurales informan la comprensión de enzimas relacionadas como BRCA1.1.

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