title: SUMO modification of the ubiquitin-conjugating enzyme E2-25K.
abstract: 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.
authors.affiliation: University of Göttingen, Department of Biochemistry I, Humboldt Allee 23, 37073 Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pichler
authors.forename: Puck
authors.initials: P
authors.lastname: Knipscheer
authors.forename: Edith
authors.initials: E
authors.lastname: Oberhofer
authors.forename: Willem J
authors.initials: WJ
authors.lastname: van Dijk
authors.forename: Roman
authors.initials: R
authors.lastname: Körner
authors.forename: Jesper Velgaard
authors.initials: JV
authors.lastname: Olsen
authors.forename: Stefan
authors.initials: S
authors.lastname: Jentsch
authors.forename: Frauke
authors.initials: F
authors.lastname: Melchior
authors.forename: Titia K
authors.initials: TK
authors.lastname: Sixma
mesh_terms: 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*
chemical_list: D025842:SUMO-1 Protein; C100879:UBE2K protein, human; D044763:Ubiquitin-Conjugating Enzymes