Ubc9 sumoylation regulates SUMO target discrimination.
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.
Knipscheer
Puck
P
The Netherlands Cancer Institute and Center for Biomedical Genetics, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
Flotho
Annette
A
Klug
Helene
H
Olsen
Jesper V
JV
van Dijk
Willem J
WJ
Fish
Alexander
A
Johnson
Erica S
ES
Mann
Matthias
M
Sixma
Titia K
TK
Pichler
Andrea
A
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
D001324:Autoantigens; D004952:Esters; D025841:Small Ubiquitin-Related Modifier Proteins; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9