title: Structural basis of high-order oligomerization of the cullin-3 adaptor SPOP.
abstract: Protein ubiquitination in eukaryotic cells is mediated by diverse E3 ligase enzymes that each target specific substrates. The cullin E3 ligase complexes are the most abundant class of E3 ligases; they contain various cullin components that serve as scaffolds for interaction with substrate-recruiting adaptor proteins. SPOP is a BTB-domain adaptor of the cullin-3 E3 ligase complexes; it selectively recruits substrates via its N-terminal MATH domain, whereas its BTB domain mediates dimerization and interactions with cullin-3. It has recently been recognized that the high-order oligomerization of SPOP enhances the ubiquitination of substrates. Here, a dimerization interface in the SPOP C-terminus is identified and it is shown that the dimerization interfaces of the BTB domain and of the C-terminus act independently and in tandem to generate high-order SPOP oligomers. The crystal structure of the dimeric SPOP C-terminal domain is reported at 1.5 Å resolution and it is shown that Tyr353 plays a critical role in high-order oligomerization. A model of the high-order SPOP oligomer is presented that depicts a helical organization that could enhance the efficiency of substrate ubiquitination.
authors.affiliation: School of Biology, University of Leeds, Leeds LS2 9JT, England.
authors.forename: Laura K
authors.initials: LK
authors.lastname: van Geersdaele
authors.forename: Mark A
authors.initials: MA
authors.lastname: Stead
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Harrison
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Carr
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Close
authors.forename: Gareth O
authors.initials: GO
authors.lastname: Rosbrook
authors.forename: Simon D
authors.initials: SD
authors.lastname: Connell
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Wright
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry; D018360:Crystallography, X-Ray; D044842:Cullin Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D006801:Humans; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary / Q000235:genetics; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D013379:Substrate Specificity / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry*; D054875:Ubiquitination / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: C503645:CUL3 protein, human; D002352:Carrier Proteins; D044842:Cullin Proteins; D009687:Nuclear Proteins; C479529:RBX1 protein, human; D012097:Repressor Proteins; C509761:SPOP protein, human; D044767:Ubiquitin-Protein Ligases
keywords: BACK domains; E3 ligases; POZ domains; ubiquitination