RNF4-dependent hybrid SUMO-ubiquitin chains are signals for RAP80 and thereby mediate the recruitment of BRCA1 to sites of DNA damage.

Abstract

The DNA repair function of the breast cancer susceptibility protein BRCA1 depends in part on its interaction with RAP80, which targets BRCA1 to DNA double-strand breaks (DSBs) through recognition of K63-linked polyubiquitin chains. The localization of BRCA1 to DSBs also requires sumoylation. We demonstrated that, in addition to having ubiquitin-interacting motifs, RAP80 also contains a SUMO-interacting motif (SIM) that is critical for recruitment to DSBs. In combination with the ubiquitin-binding activity of RAP80, this SIM enabled RAP80 to bind with nanomolar affinity to hybrid chains consisting of ubiquitin conjugated to SUMO. Furthermore, RNF4, a SUMO-targeted ubiquitin E3 ligase that synthesizes hybrid SUMO-ubiquitin chains, localized to DSBs and was critical for the recruitment of RAP80 and BRCA1 to sites of DNA damage. Our findings, therefore, connect ubiquitin- and SUMO-dependent DSB recognition, revealing that RNF4-synthesized hybrid SUMO-ubiquitin chains are recognized by RAP80 to promote BRCA1 recruitment and DNA repair.

• Authors: Catherine M Guzzo, Christopher E Berndsen, Jianmei Zhu, Vibhor Gupta, Ajit Datta, Roger A Greenberg, Cynthia Wolberger, Michael J Matunis
• Journal: Science signaling (Sci Signal) Vol. 5 Issue 253 Pg. ra88 (Dec 04 2012) ISSN: 1937-9145 [Electronic] United States
• PMID: 23211528 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• BRCA1 Protein
• BRCA1 protein, human
• Carrier Proteins
• DNA-Binding Proteins
• Histone Chaperones
• Nuclear Proteins
• RNF4 protein, human
• SUMO-1 Protein
• Transcription Factors
• UIMC1 protein, human
• Ubiquitins
• Ubiquitin-Protein Ligases

Topics

• Amino Acid Motifs
• BRCA1 Protein (genetics, metabolism)
• Carrier Proteins (genetics, metabolism)
• Cell Line, Tumor
• DNA Breaks, Double-Stranded
• DNA Repair (physiology)
• DNA-Binding Proteins
• Histone Chaperones
• Humans
• Nuclear Proteins (genetics, metabolism)
• SUMO-1 Protein (genetics, metabolism)
• Sumoylation
• Transcription Factors (genetics, metabolism)
• Ubiquitin-Protein Ligases (genetics, metabolism)
• Ubiquitins (genetics, metabolism)