SUMO modification of the ubiquitin-conjugating enzyme E2-25K.
Post-translational modification with small ubiquitin-related modifier (SUMO) alters the function of many proteins, but the molecular mechanisms and consequences of this modification are still poorly defined. During a screen for novel SUMO1 targets, we identified the ubiquitin-conjugating enzyme E2-25K (Hip2). SUMO attachment severely impairs E2-25K ubiquitin thioester and unanchored ubiquitin chain formation in vitro. Crystal structures of E2-25K(1-155) and of the E2-25K(1-155)-SUMO conjugate (E2-25K(*)SUMO) indicate that SUMO attachment interferes with E1 interaction through its location on the N-terminal helix. The SUMO acceptor site in E2-25K, Lys14, does not conform to the consensus site found in most SUMO targets (PsiKXE), and functions only in the context of an alpha-helix. In contrast, adjacent SUMO consensus sites are modified only when in unstructured peptides. The demonstration that secondary structure elements are part of SUMO attachment signals could contribute to a better prediction of SUMO targets.
Pichler
Andrea
A
University of Göttingen, Department of Biochemistry I, Humboldt Allee 23, 37073 Göttingen, Germany.
Knipscheer
Puck
P
Oberhofer
Edith
E
van Dijk
Willem J
WJ
Körner
Roman
R
Olsen
Jesper Velgaard
JV
Jentsch
Stefan
S
Melchior
Frauke
F
Sixma
Titia K
TK
D000595:Amino Acid Sequence; D016384:Consensus Sequence; D003460:Crystallization; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D017433:Protein Structure, Secondary; D025842:SUMO-1 Protein / Q000378:metabolism / Q000502:physiology*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*
D025842:SUMO-1 Protein; C100879:UBE2K protein, human; D044763:Ubiquitin-Conjugating Enzymes