The penta-domain, chromatin-associated protein UHRF1 has been shown to exist in a multi-protein complex with several key multi-domain epigenetic enzymes, including DNA methyltransferase I (DNMT1), the deubiquitylase ubiquitin-specific protease 7 (USP7),and histone deacetyltransferases (HDAC). Together these proteins cooperate to ensure the proper functioning of key biological processes such as cell proliferation and transcription regulation. UHRF1 is proposed to be a substrate for USP7, which is known to regulate the levels of p53 and its related proteins by deubiquitylation. Our study clarified the molecular basis of interaction between UHRF1 and USP7 and revealed that
one of the long-spanning inter-domain linker region in UHRF1 forms the basis for its capability to associate with USP7. We identified a variation from the previously reported consensus MATH binding sequence, an AxxxPS motif in UHRF1 that is specifically recognized by the USP7 MATH domain. In addition, we showed that the first two UBL domains of USP7 can also potentially bind to UHRF1, and that the simultaneous binding
of the two USP7 domains to UHRF1 result in disruption of UHRF1 binding to hemimethylated DNA. We propose a mechanism of action for USP7-UHRF1 complex formation in the nucleoplasm and chromatin-bound compartments.