Unique binding interactions among Ubc9, SUMO and RanBP2 reveal a mechanism for SUMO paralog selection.
The conjugation of small ubiquitin-like modifiers SUMO-1, SUMO-2 and SUMO-3 onto target proteins requires the concerted action of the specific E1-activating enzyme SAE1/SAE2, the E2-conjugating enzyme Ubc9, and an E3-like SUMO ligase. NMR chemical shift perturbation was used to identify the surface of Ubc9 that interacts with the SUMO ligase RanBP2. Unlike known ubiquitin E2-E3 interactions, RanBP2 binds to the beta-sheet of Ubc9. Mutational disruption of Ubc9-RanBP2 binding affected SUMO-2 but not SUMO-1 conjugation to Sp100 and to a newly identified RanBP2 substrate, PML. RanBP2 contains a binding site specific for SUMO-1 but not SUMO-2, indicating that a Ubc9-SUMO-1 thioester could be recruited to RanBP2 via SUMO-1 in the absence of strong binding between Ubc9 and RanBP2. Thus we show that E2-E3 interactions are not conserved across the ubiquitin-like protein superfamily and identify a RanBP2-dependent mechanism for SUMO paralog-specific conjugation.
Tatham
Michael H
MH
Centre for Biomolecular Sciences, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST, UK.
Kim
Suhkmann
S
Jaffray
Ellis
E
Song
Jing
J
Chen
Yuan
Y
Hay
Ronald T
RT
D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; C094493:ran-binding protein 2; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9