title: 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.affiliation: Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Guzzo
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Berndsen
authors.forename: Jianmei
authors.initials: J
authors.lastname: Zhu
authors.forename: Vibhor
authors.initials: V
authors.lastname: Gupta
authors.forename: Ajit
authors.initials: A
authors.lastname: Datta
authors.forename: Roger A
authors.initials: RA
authors.lastname: Greenberg
authors.forename: Cynthia
authors.initials: C
authors.lastname: Wolberger
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Matunis
mesh_terms: D020816:Amino Acid Motifs; D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology; D004268:DNA-Binding Proteins; D056488:Histone Chaperones; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D058207:Sumoylation; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D056488:Histone Chaperones; D009687:Nuclear Proteins; C114070:RNF4 protein, human; D025842:SUMO-1 Protein; D014157:Transcription Factors; C466234:UIMC1 protein, human; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases