title: Ubc9 sumoylation regulates SUMO target discrimination.
abstract: Posttranslational modification with small ubiquitin-related modifier, SUMO, is a widespread mechanism for rapid and reversible changes in protein function. Considering the large number of known targets, the number of enzymes involved in modification seems surprisingly low: a single E1, a single E2, and a few distinct E3 ligases. Here we show that autosumoylation of the mammalian E2-conjugating enzyme Ubc9 at Lys14 regulates target discrimination. While not altering its activity toward HDAC4, E2-25K, PML, or TDG, sumoylation of Ubc9 impairs its activity on RanGAP1 and strongly activates sumoylation of the transcriptional regulator Sp100. Enhancement depends on a SUMO-interacting motif (SIM) in Sp100 that creates an additional interface with the SUMO conjugated to the E2, a mechanism distinct from Ubc9 approximately SUMO thioester recruitment. The crystal structure of sumoylated Ubc9 demonstrates how the newly created binding interface can provide a gain in affinity otherwise provided by E3 ligases.
authors.affiliation: The Netherlands Cancer Institute and Center for Biomedical Genetics, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
authors.forename: Puck
authors.initials: P
authors.lastname: Knipscheer
authors.forename: Annette
authors.initials: A
authors.lastname: Flotho
authors.forename: Helene
authors.initials: H
authors.lastname: Klug
authors.forename: Jesper V
authors.initials: JV
authors.lastname: Olsen
authors.forename: Willem J
authors.initials: WJ
authors.lastname: van Dijk
authors.forename: Alexander
authors.initials: A
authors.lastname: Fish
authors.forename: Erica S
authors.initials: ES
authors.lastname: Johnson
authors.forename: Matthias
authors.initials: M
authors.lastname: Mann
authors.forename: Titia K
authors.initials: TK
authors.lastname: Sixma
authors.forename: Andrea
authors.initials: A
authors.lastname: Pichler
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001324:Autoantigens / Q000378:metabolism; D018360:Crystallography, X-Ray; D004952:Esters / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D013379:Substrate Specificity; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D001324:Autoantigens; D004952:Esters; D025841:Small Ubiquitin-Related Modifier Proteins; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9