2p63
From Proteopedia
Suprafacial orientation of the SCFCdc4 dimer accommodates multiple geometries for substrate ubiquitination
Structural highlights
Function[CDC4_YEAST] Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Recognizes and binds to phosphorylated target proteins. Directs ubiquitination of the phosphorylated CDK inhibitor SIC1. Involved in the degradation of CDC6 together with CDC34/UBC3 and CDC53, and in restricting the degradation of FAR1 to the nucleus. Is essential for initiation of DNA replication and separation of the spindle pole bodies to form the poles of the mitotic spindle. It also plays a role in bud development, fusion of zygotic nuclei after conjugation and various aspects of sporulation. Required for HTA1-HTB1 locus transcription activation. Required for G1/S and G2/M transition.[1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedSCF ubiquitin ligases recruit substrates for degradation via F box protein adaptor subunits. WD40 repeat F box proteins, such as Cdc4 and beta-TrCP, contain a conserved dimerization motif called the D domain. Here, we report that the D domain protomers of yeast Cdc4 and human beta-TrCP form a superhelical homotypic dimer. Disruption of the D domain compromises the activity of yeast SCF(Cdc4) toward the CDK inhibitor Sic1 and other substrates. SCF(Cdc4) dimerization has little effect on the affinity for Sic1 but markedly stimulates ubiquitin conjugation. A model of the dimeric holo-SCF(Cdc4) complex based on small-angle X-ray scatter measurements reveals a suprafacial configuration, in which substrate-binding sites and E2 catalytic sites lie in the same plane with a separation of 64 A within and 102 A between each SCF monomer. This spatial variability may accommodate diverse acceptor lysine geometries in both substrates and the elongating ubiquitin chain and thereby increase catalytic efficiency. Suprafacial orientation of the SCFCdc4 dimer accommodates multiple geometries for substrate ubiquitination.,Tang X, Orlicky S, Lin Z, Willems A, Neculai D, Ceccarelli D, Mercurio F, Shilton BH, Sicheri F, Tyers M Cell. 2007 Jun 15;129(6):1165-76. PMID:17574027[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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