title: Proximity-induced activation of human Cdc34 through heterologous dimerization.
abstract: Cdc34 is an E2-conjugating enzyme required for catalyzing the polyubiquitination reaction mediated by the Skp1.CUL1.F-box (SCF) protein E3 ubiquitin (Ub) ligase. Here, we show that the activity of human Cdc34 in the Ub-Ub ligation reaction was enhanced dramatically by SCF's core Ub ligase module, composed of a heterodimeric complex formed by the ROC1 RING finger protein and the CUL1 C terminus that contains a Nedd8 moiety covalently conjugated at K720. Unexpectedly, we found that N-terminal fusion of a GST moiety to human Cdc34 generated dimeric GST-Cdc34 that was constitutively active in supporting the assembly of K48-linked polyUb chains independently of SCF. Furthermore, fusion of a FK506-binding protein (FKBP) to the N terminus of human Cdc34 yielded FKBP-Cdc34 that was induced to form a dimer upon treatment with the chemical inducer AP20187. The AP20187-induced dimeric form of FKBP-Cdc34 was substantially more active than the monomer in catalyzing Ub-Ub ligation. Thus, juxtaposition of human Cdc34 activates its catalytic capability, suggesting that the SCF-mediated polyubiquitination reaction may require the conversion of Cdc34 from an inactive monomer to a highly active dimeric form.
authors.affiliation: Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
authors.forename: Stefan
authors.initials: S
authors.lastname: Gazdoiu
authors.forename: Kosj
authors.initials: K
authors.lastname: Yamoah
authors.forename: Kenneth
authors.initials: K
authors.lastname: Wu
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Escalante
authors.forename: Inger
authors.initials: I
authors.lastname: Tappin
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bermudez
authors.forename: Aneel K
authors.initials: AK
authors.lastname: Aggarwal
authors.forename: Jerard
authors.initials: J
authors.lastname: Hurwitz
authors.forename: Zhen-Qiang
authors.initials: ZQ
authors.lastname: Pan
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism; D019281:Dimerization; D004789:Enzyme Activation; D006801:Humans; D025821:Polyubiquitin / Q000096:biosynthesis; D020836:Protein Structure, Quaternary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016559:Tacrolimus / Q000031:analogs & derivatives / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C463061:AP20187; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; C479529:RBX1 protein, human; D011993:Recombinant Fusion Proteins; D025821:Polyubiquitin; C577447:CDC34 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D022021:Tacrolimus Binding Proteins; D016559:Tacrolimus