Posttranslational histone modifications play important roles in transcription and other chromatin-based processes. Compared to acetylation, methylation, and phosphorylation, very little is known about the function of histone ubiquitylation. Here, we report the purification and functional characterization of a histone H3 and H4 ubiquitin ligase complex, CUL4-DDB-ROC1. We demonstrate that CUL4-DDB-ROC1-mediated H3 and H4 ubiquitylation occurs both in vitro and in vivo. Importantly, CUL4-DDB-ROC1-mediated H3 and H4 ubiquitylation is regulated by UV irradiation. Reduction of histone H3 and H4 ubiquitylation by knockdown of CUL4A impairs recruitment of the repair protein XPC to the damaged foci and inhibits the repair process. Biochemical studies indicate that CUL4-DDB-ROC1-mediated histone ubiquitylation weakens the interaction between histones and DNA and facilitates the recruitment of repair proteins to damaged DNA. Thus, our studies uncover CUL4-DDB-ROC1 as a histone ubiquitin ligase and demonstrate that histone H3 and H4 ubiquitylation participates in the cellular response to DNA damage.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.