Cdt1 variants reveal unanticipated aspects of interactions with cyclin/CDK and MCM important for normal genome replication
| Autor: | Pedro N. Pozo, Jeanette Gowen Cook, Gavin D. Grant, Yasemin Cole, Brenda Temple, Jacob Peter Matson, Katarzyna M. Kedziora |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
DNA Replication
0301 basic medicine Micrognathism Cyclin A Mutation Missense Cell Cycle Proteins medicine.disease_cause Cell Line S Phase DNA replication factor CDT1 chemistry.chemical_compound 03 medical and health sciences 0302 clinical medicine Minichromosome maintenance Cyclin-dependent kinase medicine Humans S-Phase Kinase-Associated Proteins Molecular Biology Alleles Growth Disorders Congenital Microtia 030304 developmental biology Cyclin 0303 health sciences Mutation Binding Sites Minichromosome Maintenance Proteins biology Genome Human Chemistry Cell Cycle DNA replication Genetic Variation Helicase Articles Patella Cell Biology Cell cycle Cell biology HEK293 Cells 030104 developmental biology 030220 oncology & carcinogenesis embryonic structures biology.protein DNA Protein Binding |
| Zdroj: | Molecular Biology of the Cell |
| ISSN: | 1939-4586 1059-1524 |
| Popis: | The earliest step in DNA replication is origin licensing, which is the DNA loading of minichromosome maintenance (MCM) helicase complexes. The Cdc10-dependent transcript 1 (Cdt1) protein is essential for MCM loading during the G1 phase of the cell cycle, but the mechanism of Cdt1 function is still incompletely understood. We examined a collection of rare Cdt1 variants that cause a form of primordial dwarfism (the Meier–Gorlin syndrome) plus one hypomorphic Drosophila allele to shed light on Cdt1 function. Three hypomorphic variants load MCM less efficiently than wild-type (WT) Cdt1, and their lower activity correlates with impaired MCM binding. A structural homology model of the human Cdt1–MCM complex positions the altered Cdt1 residues at two distinct interfaces rather than the previously described single MCM interaction domain. Surprisingly, one dwarfism allele ( Cdt1-A66T) is more active than WT Cdt1. This hypermorphic variant binds both cyclin A and SCFSkp2poorly relative to WT Cdt1. Detailed quantitative live-cell imaging analysis demonstrated no change in the stability of this variant, however. Instead, we propose that cyclin A/CDK inhibits the Cdt1 licensing function independent of the creation of the SCFSkp2phosphodegron. Together, these findings identify key Cdt1 interactions required for both efficient origin licensing and tight Cdt1 regulation to ensure normal cell proliferation and genome stability. |
| Databáze: | OpenAIRE |
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