Programmed destruction of regulatory proteins through the ubiquitin–proteasome system is a widely used mechanism for controlling signalling pathways1,2. Cullins3 are proteins that function as scaffolds for modular ubiquitin ligases typified by the SCF (Skp1–Cul1–F-box) complex4,5,6. The substrate selectivity of these E3 ligases is dictated by a specificity module that binds cullins. In the SCF complex, this module is composed of Skp1, which binds directly to Cul1, and a member of the F-box family of proteins4,5,6,7. F-box proteins bind Skp1 through the F-box motif7, and substrates by means of carboxy-terminal protein interaction domains1,2,5. Similarly, Cul2 and Cul5 interact with BC-box-containing specificity factors through the Skp1-like protein elongin C2. Cul3 is required for embryonic development in mammals and Caenorhabditis elegans8,9,10 but its specificity module is unknown. Here we report the identification of a large family of BTB-domain proteins as substrate-specific adaptors for C. elegans CUL-3. Biochemical studies using the BTB protein MEL-26 and its genetic target MEI-1 (refs 12, 13) indicate that BTB proteins merge the functional properties of Skp1 and F-box proteins into a single polypeptide.
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Koepp, D. M., Harper, J. W. & Elledge, S. J. How the cyclin became a cyclin: regulated proteolysis in the cell cycle. Cell 97, 431–434 (1999)
Deshaies, R. J. SCF and Cullin/Ring H2-based ubiquitin ligases. Annu. Rev. Cell Dev. Biol. 15, 435–467 (1999)
Kipreos, E. T., Lander, L. E., Wing, J. P., He, W. W. & Hedgecock, E. M. cul-1 is required for cell cycle exit in C. elegans and identifies a novel gene family. Cell 85, 829–839 (1996)
Zheng, N. et al. Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF ubiquitin ligase complex. Nature 416, 703–709 (2002)
Skowyra, D., Craig, K. L., Tyers, M., Elledge, S. J. & Harper, J. W. F-box proteins are receptors that recruit phosphorylated substrates to the SCF ubiquitin-ligase complex. Cell 91, 209–219 (1997)
Feldman, R. M., Correll, C. C., Kaplan, K. B. & Deshaies, R. J. A complex of Cdc4p, Skp1p, and Cdc53p/cullin catalyzes ubiquitination of the phosphorylated CDK inhibitor Sic1p. Cell 91, 209–219 (1997)
Bai, C. et al. Skp1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box. Cell 86, 263–274 (1999)
Singer, J. D., Gurian-West, M., Clurman, B. & Roberts, J. M. Cullin-3 targets cyclin E for ubiquitination and controls S phase in mammalian cells. Genes Dev. 13, 2375–2387 (1999)
Winston, J. T., Chu, C. & Harper, J. W. Culprits in the degradation of cyclin E apprehended. Genes Dev. 13, 2751–2757 (1999)
Kurz, T. et al. Cytoskeletal regulation by the Nedd8 ubiquitin-like protein modification pathway. Science 295, 1294–1298 (2002)
Pintard, L. et al. Neddylation and deneddylation of CUL-3 is required to target MEI-1/Katanin for degradation at the meiosis-to-mitosis transition in C. elegans. Curr. Biol. 13, 911–921 (2003)
Dow, M. R. & Mains, P. E. Genetic and molecular characterization of the Caenorhabditis elegans gene, mel-26, a postmeiotic negative regulator of mei-1, a meiotic-specific spindle component. Genetics 150, 119–128 (1998)
Clark-Maguire, S. & Mains, P. E. mei-1, a gene required for meiotic spindle formation in Caenorhabditis elegans, is a member of a family of ATPases. Genetics 136, 533–546 (1994)
Reboul, J. et al. C. elegans ORFeome version 1.1: experimental verification of the genome annotation and resource for proteome-scale protein expression. Nature Genet. 34, 35–41 (2003)
Collins, T., Stone, J. R. & Williams, A. J. All in the family: the BTB/POZ, KRAB, and SCAN domains. Mol. Cell. Biol. 21, 3609–3615 (2001)
Schulman, B. A. et al. Insights into SCF ubiquitin ligases from the structure of the Skp1–Skp2 complex. Nature 408, 381–386 (2000)
Aravind, L. & Koonin, E. V. Fold prediction and evolutionary analysis of the POZ domain: structural and evolutionary relationship with the potassium channel tetramerization domain. J. Mol. Biol. 285, 1353–1361 (1999)
Uren, A. G. & Vaux, D. L. TRAF proteins and meprins share a conserved domain. Trends Biochem. 21, 244–245 (1996)
Pintard, L. et al. The BTB protein MEL-26 functions as a substrate-specific adaptor of the CUL-3 ubiquitin-ligase. Nature advance online publication; 3 September 2003 (doi:10.1038/nature01959)
Srayko, M., Buster, D. W., Bazirgan, O. A., McNally, F. J. & Mains, P. E. MEI-1/MEI-2 katanin-like microtubule severing activity is required for Caenorhabditis elegans meiosis. Genes Dev. 14, 1072–1084 (2000)
Ye, H., Park, Y. C., Kreishman, M., Kieff, E. & Wu, H. The structural basis for the recognition of diverse receptor sequences by TRAF2. Mol. Cell 4, 321–330 (1991)
Zhou, P. & Howley, P. Ubiquitination and degradation of the substrate recognition subunits of SCF ubiquitin-protein ligases. Mol. Cell 2, 571–580 (1998)
Walhout, A. J. et al. Protein interaction mapping in C. elegans using proteins involved in vulval development. Science 287, 116–122 (2000)
We thank M. Peter for anti-CUL-3 and anti-MEL-26 antibodies. This work was supported by an NIH grant (to J.W.H. and S.J.E.), the Welch Foundation (to J.W.H.), and the National Human Genome Research Institute (to M.V.). Y.W. was supported by a Department of Defense predoctoral fellowship. S.J.E. is an investigator of the Howard Hughes Medical Institute.
The authors declare that they have no competing financial interests.
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Human Molecular Genetics (2019)
Human Molecular Genetics (2019)
Frontiers in Immunology (2019)
JCI Insight (2019)