title: Ubiquitin-conjugating enzyme Cdc34 and ubiquitin ligase Skp1-cullin-F-box ligase (SCF) interact through multiple conformations.
abstract: In the ubiquitin-proteasome system, protein substrates are degraded via covalent modification by a polyubiquitin chain. The polyubiquitin chain must be assembled rapidly in cells, because a chain of at least four ubiquitins is required to signal for degradation, and chain-editing enzymes in the cell may cleave premature polyubiquitin chains before achieving this critical length. The ubiquitin-conjugating enzyme Cdc34 and ubiquitin ligase SCF are capable of building polyubiquitin chains onto protein substrates both rapidly and processively; this may be explained at least in part by the atypically fast rate of Cdc34 and SCF association. This rapid association has been attributed to electrostatic interactions between the acidic C-terminal tail of Cdc34 and a feature on SCF called the basic canyon. However, the structural aspects of the Cdc34-SCF interaction and how they permit rapid complex formation remain elusive. Here, we use protein cross-linking to demonstrate that the Cdc34-SCF interaction occurs in multiple conformations, where several residues from the Cdc34 acidic tail are capable of contacting a broad region of the SCF basic canyon. Similar patterns of cross-linking are also observed between Cdc34 and the Cul1 paralog Cul2, implicating the same mechanism for the Cdc34-SCF interaction in other members of the cullin-RING ubiquitin ligases. We discuss how these results can explain the rapid association of Cdc34 and SCF.
authors.affiliation: From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154-4003 and.
authors.forename: Daniella
authors.initials: D
authors.lastname: Sandoval
authors.affiliation: From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154-4003 and.
authors.forename: Spencer
authors.initials: S
authors.lastname: Hill
authors.affiliation: From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154-4003 and.
authors.forename: Amy
authors.initials: A
authors.lastname: Ziemba
authors.affiliation: the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260.
authors.forename: Steven
authors.initials: S
authors.lastname: Lewis
authors.affiliation: the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260.
authors.forename: Brian
authors.initials: B
authors.lastname: Kuhlman
authors.affiliation: From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154-4003 and gary.kleiger@unlv.edu.
authors.forename: Gary
authors.initials: G
authors.lastname: Kleiger
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D044842:Cullin Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D044786:S-Phase Kinase-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C100318:Cullin 1; D044842:Cullin Proteins; D044786:S-Phase Kinase-Associated Proteins; C097351:SKP1 protein, human; D025801:Ubiquitin; C577447:CDC34 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D064173:Anaphase-Promoting Complex-Cyclosome; D044843:SKP Cullin F-Box Protein Ligases
keywords: E3 Ubiquitin Ligase; Protein-Protein Interaction; Ubiquitin; Ubiquitin-conjugating Enzyme (E2 Enzyme); Ubiquitylation (Ubiquitination)