Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF ubiquitin ligase complex.
SCF complexes are the largest family of E3 ubiquitin-protein ligases and mediate the ubiquitination of diverse regulatory and signalling proteins. Here we present the crystal structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF complex, which shows that Cul1 is an elongated protein that consists of a long stalk and a globular domain. The globular domain binds the RING finger protein Rbx1 through an intermolecular beta-sheet, forming a two-subunit catalytic core that recruits the ubiquitin-conjugating enzyme. The long stalk, which consists of three repeats of a novel five-helix motif, binds the Skp1-F boxSkp2 protein substrate-recognition complex at its tip. Cul1 serves as a rigid scaffold that organizes the Skp1-F boxSkp2 and Rbx1 subunits, holding them over 100 A apart. The structure suggests that Cul1 may contribute to catalysis through the positioning of the substrate and the ubiquitin-conjugating enzyme, and this model is supported by Cul1 mutations designed to eliminate the rigidity of the scaffold.
Zheng
Ning
N
Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York 10021, USA.
Schulman
Brenda A
BA
Song
Langzhou
L
Miller
Julie J
JJ
Jeffrey
Philip D
PD
Wang
Ping
P
Chu
Claire
C
Koepp
Deanna M
DM
Elledge
Stephen J
SJ
Pagano
Michele
M
Conaway
Ronald C
RC
Conaway
Joan W
JW
Harper
J Wade
JW
Pavletich
Nikola P
NP
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D044842:Cullin Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D006801:Humans; D008025:Ligases / Q000737:chemistry* / Q000378:metabolism; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000075687:NEDD8 Protein; D010453:Peptide Synthases / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D044786:S-Phase Kinase-Associated Proteins; D044843:SKP Cullin F-Box Protein Ligases; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism
D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D046911:Macromolecular Substances; D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; D044786:S-Phase Kinase-Associated Proteins; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; D014452:Ubiquitins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D044763:Ubiquitin-Conjugating Enzymes; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D010453:Peptide Synthases