Abstract
Cul4 E3 ubiquitin ligases contain the cullin 4 scaffold and the triple beta propeller Ddb1 adaptor protein, but few substrate receptors have been identified. Here, we identify 18 Ddb1- and Cul4-associated factors (DCAFs), including 14 containing WD40 repeats. DCAFs interact with multiple surfaces on Ddb1, and the interaction of WD40-containing DCAFs with Ddb1 requires a conserved "WDXR" motif. DCAF2/Cdt2, which is related to S. pombe Cdt2, functions in Xenopus egg extracts and human cells to destroy the replication licensing protein Cdt1 in S phase and after DNA damage. Depletion of human Cdt2 causes rereplication and checkpoint activation. In Xenopus, Cdt2 is recruited to replication forks via Cdt1 and PCNA, where Cdt1 ubiquitylation occurs. These studies uncover diverse substrate receptors for Cul4 and identify Cdt2 as a conserved component of the Cul4-Ddb1 E3 that is essential to destroy Cdt1 and ensure proper cell cycle regulation of DNA replication.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / chemistry
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Adaptor Proteins, Signal Transducing / metabolism*
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Amino Acid Motifs
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Amino Acid Sequence
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Animals
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Cell Cycle Proteins / metabolism*
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Chromatin / metabolism
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Cullin Proteins / metabolism*
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DNA Damage
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DNA Replication / genetics
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DNA-Binding Proteins / metabolism*
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G2 Phase
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HeLa Cells
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Humans
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Molecular Sequence Data
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Nuclear Proteins
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Protein Binding
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Protein Processing, Post-Translational*
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Receptors, Cell Surface / metabolism
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Reproducibility of Results
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S Phase*
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Ubiquitin-Protein Ligases / metabolism
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Xenopus Proteins / metabolism
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Xenopus laevis
Substances
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Adaptor Proteins, Signal Transducing
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CDT1 protein, human
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CUL4A protein, human
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Cell Cycle Proteins
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Chromatin
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Cullin Proteins
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DDB1 protein, human
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DNA-Binding Proteins
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DTL protein, human
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Nuclear Proteins
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Receptors, Cell Surface
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Xenopus Proteins
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Ubiquitin-Protein Ligases