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The nucleosome acidic patch plays a critical role in RNF168-dependent ubiquitination of histone H2A.

ABSTRACT: During DNA damage response, the RING E3 ligase RNF168 ubiquitinates nucleosomal H2A at K13-15. Here we show that the ubiquitination reaction is regulated by its substrate. We define a region on the RING domain important for target recognition and identify the H2A/H2B dimer as the minimal substrate to confer lysine specificity to the RNF168 reaction. Importantly, we find an active role for the substrate in the reaction. H2A/H2B dimers and nucleosomes enhance the E3-mediated discharge of ubiquitin from the E2 and redirect the reaction towards the relevant target, in a process that depends on an intact acidic patch. This active contribution of a region distal from the target lysine provides regulation of the specific K13-15 ubiquitination reaction during the complex signalling process at DNA damage sites.

SUBMITTER: Mattiroli F

PROVIDER: S-EPMC3929782 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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The nucleosome acidic patch plays a critical role in RNF168-dependent ubiquitination of histone H2A.

Mattiroli Francesca F Uckelmann Michael M Sahtoe Danny D DD van Dijk Willem J WJ Sixma Titia K TK

Nature communications 20140101

During DNA damage response, the RING E3 ligase RNF168 ubiquitinates nucleosomal H2A at K13-15. Here we show that the ubiquitination reaction is regulated by its substrate. We define a region on the RING domain important for target recognition and identify the H2A/H2B dimer as the minimal substrate to confer lysine specificity to the RNF168 reaction. Importantly, we find an active role for the substrate in the reaction. H2A/H2B dimers and nucleosomes enhance the E3-mediated discharge of ubiquitin ...[more]

PMID: 24518117

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Project description:Chromatin architecture is regulated through both enzymatic and non-enzymatic activities. For example, the Polycomb Group (PcG) proteins maintain developmental gene silencing using an array of chromatin-based mechanisms. The essential Drosophila PcG protein, Posterior Sex Combs (PSC), compacts chromatin and inhibits chromatin remodeling and transcription through a non-enzymatic mechanism involving nucleosome bridging. Nucleosome bridging is achieved through a combination of nucleosome binding and self-interaction. Precisely how PSC interacts with chromatin to bridge nucleosomes is not known and is the subject of this work. We determine the stoichiometry of PSC-chromatin interactions in compact chromatin (in which nucleosomes are bridged) using Scanning Transmission Electron Microscopy (STEM). We find that full compaction occurs with one PSC per nucleosome. In addition to compacting chromatin, we show that PSC oligomerizes nucleosome arrays. PSC-mediated oligomerization of chromatin occurs at similar stoichiometry as compaction suggesting it may also involve nucleosome bridging. Interactions between the tail of histone H4 and the acidic patch of histone H2A are important for chromatin folding and oligomerization, and several chromatin proteins bind the histone H2A acidic patch. However, mutation of the acidic patch of histone H2A does not affect PSC's ability to inhibit chromatin remodeling or bridge nucleosomes. In fact, PSC does not require nucleosomes for bridging activity but can bridge naked DNA segments. PSC clusters nucleosomes on sparsely assembled templates, suggesting it interacts preferentially with nucleosomes over bare DNA. This may be due to the ability of PSC to bind free histones. Our data are consistent with a model in which each PSC binds a nucleosome and at least one other PSC to directly bridge nucleosomes and compact chromatin, but also suggest that naked DNA can be included in compacted structures. We discuss how our data highlight the diversity of mechanisms used to modify chromatin architecture.

Dataset Information

The nucleosome acidic patch plays a critical role in RNF168-dependent ubiquitination of histone H2A.

Publications

The nucleosome acidic patch plays a critical role in RNF168-dependent ubiquitination of histone H2A.

Similar Datasets

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