2n9e
From Proteopedia
Structure of SUMO-2 bound to phosphorylated RAP80 SIM
Structural highlights
Function[UIMC1_HUMAN] Ubiquitin-binding protein that specifically recognizes and binds 'Lys-63'-linked ubiquitin. Plays a central role in the BRCA1-A complex by specifically binding 'Lys-63'-linked ubiquitinated histones H2A and H2AX at DNA lesions sites, leading to target the BRCA1-BARD1 heterodimer to sites of DNA damage at double-strand breaks (DSBs). The BRCA1-A complex also possesses deubiquitinase activity that specifically removes 'Lys-63'-linked ubiquitin on histones H2A and H2AX. Also weakly binds monoubiquitin but with much less affinity than 'Lys-63'-linked ubiquitin. May interact with monoubiquitinated histones H2A and H2B; the relevance of such results is however unclear in vivo. Does not bind Lys-48'-linked ubiquitin. May indirectly act as a transcriptional repressor by inhibiting the interaction of NR6A1 with the corepressor NCOR1.[1] [2] [3] [4] [5] [6] [7] [8] [9] [SUMO2_HUMAN] Ubiquitin-like protein that can be covalently attached to proteins as a monomer or as a lysine-linked polymer. Covalent attachment via an isopeptide bond to its substrates requires prior activation by the E1 complex SAE1-SAE2 and linkage to the E2 enzyme UBE2I, and can be promoted by an E3 ligase such as PIAS1-4, RANBP2 or CBX4. This post-translational modification on lysine residues of proteins plays a crucial role in a number of cellular processes such as nuclear transport, DNA replication and repair, mitosis and signal transduction. Polymeric SUMO2 chains are also susceptible to polyubiquitination which functions as a signal for proteasomal degradation of modified proteins.[10] [11] [12] Publication Abstract from PubMedRecognition and repair of double stranded DNA breaks (DSB) involves the targeted recruitment of BRCA tumor suppressors to damage foci through binding of both ubiquitin (Ub) and the Ub-like modifier SUMO. RAP80 is a component of the BRCA1 A complex, and plays a key role in the recruitment process through the binding of K63-linked polyUb chains by tandem Ub interacting motifs (UIM). RAP80 also contains a SUMO interacting motif (SIM) just upstream of the tandem UIMs that has been shown to specifically bind the SUMO-2 isoform. The RAP80 tandem UIMs and SIM function collectively for optimal recruitment of BRCA1 to DSBs, though the molecular basis of this process is not well understood. Using NMR spectroscopy, we demonstrate that the RAP80 SIM binds SUMO-2, and that both specificity and affinity are enhanced through phosphorylation of the canonical CK2 site within the SIM. The affinity increase results from an enhancement of electrostatic interactions between the phosphoserines of RAP80 and the SIM recognition module within SUMO-2. The NMR structure of the SUMO-2/phosphoRAP80 complex reveals that the molecular basis for SUMO-2 specificity is due to isoform-specific sequence differences in electrostatic SIM recognition modules. Molecular Basis for Phosphorylation Dependent SUMO Recognition by the DNA Repair Protein RAP80.,Anamika, Spyracopoulos L J Biol Chem. 2015 Dec 30. pii: jbc.M115.705061. PMID:26719330[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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