Highly stable loading of Mcm proteins onto chromatin in living cells requires replication to unload
| Autor: | Kristin L. Hazelwood, David M. Gilbert, Marjorie A. Kuipers, Korey A. Wilson, James G. McNally, Michael W. Davidson, Timothy J. Stasevich, Takayo Sasaki |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
DNA Replication
Cell Survival Cell Cycle Proteins CHO Cells Article Cell Line Mice Cricetulus Control of chromosome duplication Minichromosome maintenance Cricetinae Proliferating Cell Nuclear Antigen Animals Research Articles biology DNA replication DNA Helicases G1 Phase Helicase Cell Biology DNA MCM Protein Chromatin Cell biology Minichromosome Maintenance Complex Component 4 Protein Transport biology.protein Origin recognition complex Fluorescence Recovery After Photobleaching |
| Zdroj: | The Journal of Cell Biology |
| ISSN: | 1540-8140 |
| Popis: | Components of the minichromosome maintenance complex (Mcm2-7) remain indefinitely bound to chromatin during G1 phase and replication arrest. The heterohexameric minichromosome maintenance protein complex (Mcm2-7) functions as the eukaryotic helicase during DNA replication. Mcm2-7 loads onto chromatin during early G1 phase but is not converted into an active helicase until much later during S phase. Hence, inactive Mcm complexes are presumed to remain stably bound from early G1 through the completion of S phase. Here, we investigated Mcm protein dynamics in live mammalian cells. We demonstrate that Mcm proteins are irreversibly loaded onto chromatin cumulatively throughout G1 phase, showing no detectable exchange with a gradually diminishing soluble pool. Eviction of Mcm requires replication; during replication arrest, Mcm proteins remained bound indefinitely. Moreover, the density of immobile Mcms is reduced together with chromatin decondensation within sites of active replication, which provides an explanation for the lack of colocalization of Mcm with replication fork proteins. These results provide in vivo evidence for an exceptionally stable lockdown mechanism to retain all loaded Mcm proteins on chromatin throughout prolonged cell cycles. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|