Enzymatic assays for assessing histone deubiquitylation activity

While the post-translational modification of histones by the addition of ubiquitin was discovered decades ago, it has only recently been appreciated that the dynamic regulation of histone ubiquitylation patterns is an important mechanism for controlling a variety of biological processes. The processes include transcription, the recognition and repair of genomic damage and DNA replication, among others. Enzymes that catalyze the addition of ubiquitin to histones, such as the polycomb family, have been well-studied. In contrast, the enzymes that remove ubiquitin from histones are less well understood. The assay strategies described here provide a platform for the thorough in vitro and in vivo analysis of histone deubiquitylation. In some cases, these poorly characterized enzymes are likely to provide new opportunities for therapeutic targeting and a detailed understanding of their biochemical and biological activities is a prerequisite to these clinical advances.