Your browser version may not work well with NCBI's Web applications. More information here...
1: Mol Cell. 2005 Mar 4;17(5):695-707.
Related Articles, Links
Click here to read Click here to read
GMP synthetase stimulates histone H2B deubiquitylation by the epigenetic silencer USP7.

van der Knaap JA, Kumar BR, Moshkin YM, Langenberg K, Krijgsveld J, Heck AJ, Karch F, Verrijzer CP.

Department of Biochemistry, Center for Biomedical Genetics, Erasmus University Medical Center, PO Box 1738, 3000 DR Rotterdam, The Netherlands.

The packaging of eukaryotic genomic DNA into chromatin is modulated through a range of posttranslational histone modifications. Among these, the role of histone ubiquitylation remains poorly understood. Here, we show that the essential Drosophila ubiquitin-specific protease 7 (USP7) contributes to epigenetic silencing of homeotic genes by Polycomb (Pc). We purified USP7 from embryo nuclear extracts as a stable heteromeric complex with guanosine 5'-monophosphate synthetase (GMPS). The USP7-GMPS complex catalyzed the selective deubiquitylation of histone H2B, but not H2A. Biochemical assays confirmed the tight association between USP7 and GMPS in Drosophila embryo extracts. Similar to USP7, mutations in GMPS acted as enhancers of Pc in vivo. USP7 binding to GMPS was required for histone H2B deubiquitylation and strongly augmented deubiquitylation of the human tumor suppressor p53. Thus, GMPS can regulate the activity of a ubiquitin protease. Collectively, these results implicate a biosynthetic enzyme in chromatin control via ubiquitin regulation.

Publication Types:
PMID: 15749019 [PubMed - indexed for MEDLINE]