Structural basis for Cul3 protein assembly with the BTB-Kelch family of E3 ubiquitin ligases.
Cullin-RING ligases are multisubunit E3 ubiquitin ligases that recruit substrate-specific adaptors to catalyze protein ubiquitylation. Cul3-based Cullin-RING ligases are uniquely associated with BTB adaptors that incorporate homodimerization, Cul3 assembly, and substrate recognition into a single multidomain protein, of which the best known are BTB-BACK-Kelch domain proteins, including KEAP1. Cul3 assembly requires a BTB protein "3-box" motif, analogous to the F-box and SOCS box motifs of other Cullin-based E3s. To define the molecular basis for this assembly and the overall architecture of the E3, we determined the crystal structures of the BTB-BACK domains of KLHL11 both alone and in complex with Cul3, along with the Kelch domain structures of KLHL2 (Mayven), KLHL7, KLHL12, and KBTBD5. We show that Cul3 interaction is dependent on a unique N-terminal extension sequence that packs against the 3-box in a hydrophobic groove centrally located between the BTB and BACK domains. Deletion of this N-terminal region results in a 30-fold loss in affinity. The presented data offer a model for the quaternary assembly of this E3 class that supports the bivalent capture of Nrf2 and reveals potential new sites for E3 inhibitor design.
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Peter
P
Canning
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Christopher D O
CDO
Cooper
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Tobias
T
Krojer
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
James W
JW
Murray
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Ashley C W
ACW
Pike
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Apirat
A
Chaikuad
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Tracy
T
Keates
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Chancievan
C
Thangaratnarajah
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Viktorija
V
Hojzan
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Brian D
BD
Marsden
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Opher
O
Gileadi
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Stefan
S
Knapp
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom.
Frank
F
von Delft
Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, United Kingdom. Electronic address: alex.bullock@sgc.ox.ac.uk.
Alex N
AN
Bullock
D001665:Binding Sites; D002151:Calorimetry / Q000379:methods; D002352:Carrier Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D044842:Cullin Proteins / Q000737:chemistry*; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008968:Molecular Conformation; D010802:Phylogeny; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D025801:Ubiquitin / Q000737:chemistry; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism
C503645:CUL3 protein, human; D002352:Carrier Proteins; D044842:Cullin Proteins; C581033:KLHL11 protein, human; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex