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In Vitro Characterization of Histone Chaperones using Analytical, Pull-Down and Chaperoning Assays
Published on: December 29, 2021
Bases estructurales del reconocimiento de la histona H2A-H2B por el chaperón esencial
Maria Hondele1, Tobias Stuwe, Markus Hassler
1Department of Physiological Chemistry, Butenandt Institute and LMU Biomedical Center, Faculty of Medicine, Ludwig Maximilians University of Munich, Butenandtstrasse 5, 81377 Munich, Germany.
Nature
|May 24, 2013
Resumen
La estructura del complejo Facilitates Chromatin Transcription (FACT) revela cómo se une a las histonas H2A-H2B. Este mecanismo explica cómo FACT reorganiza los nucleosomas, mejorando los procesos de transcripción, replicación y reparación del ADN.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Facilita la transcripción de la cromatina (FACT) es un chaperón de la histona crucial.
- FACT reorganiza los nucleosomas para la transcripción, replicación y reparación del ADN.
- Anteriormente se desconocía la base estructural del reconocimiento H2A-H2B de FACT.
Objetivo del estudio:
- Para aclarar la base estructural de la interacción de FACT con el dimero de histona H2A-H2B.
- Comprender cómo la unión de FACT influye en la estructura del nucleosoma y la accesibilidad del ADN.
- Para determinar la estructura del dominio de heterodimerización FACT.
Principales métodos:
- Cristalografía de rayos X para determinar la estructura de Spt16M (un componente FACT) con H2A-H2B.
- Pruebas bioquímicas e in vivo para validar los hallazgos estructurales y analizar las interacciones histónicas.
- Análisis estructural del dominio de heterodimerización FACT.
Principales resultados:
- Se reveló la estructura cristalina del dominio chaperón FACT Spt16M unido al heterodímero H2A-H2B.
- Se identificó un nuevo motivo de "giro en U" en Spt16M que interactúa con el dimero de histona H2A-H2B.
- Se demostró que la unión de FACT facilita la "respiración" del nucleosoma al reorganizar los contactos histona-ADN.
Conclusiones:
- Las estructuras determinadas proporcionan información de alta resolución sobre las funciones esenciales de acompañamiento de FACT.
- El mecanismo de reconocimiento H2A-H2B de FACT explica su papel en la reorganización de los nucleosomas.
- Este trabajo ilumina cómo FACT facilita la actividad de enzimas que requieren remodelación de nucleosomas.
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01:12The Nucleosome Core Particle
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
02:10The Nucleosome Core Particle
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
The paradox
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their main responsibility is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. While on the other hand, they must allow polymerase enzymes to access DNA...
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
01:19The Nucleosome
Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of compaction possible, DNA is organized into several sequential levels so that it can fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
02:33The Nucleosome
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...