We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Highly stable loading of Mcm proteins onto chromatin in living cells requires replication to unload.
- Authors
Kuipers, Marjorie A; Stasevich, Timothy J; Sasaki, Takayo; Wilson, Korey A; Hazelwood, Kristin L; McNally, James G; Davidson, Michael W; Gilbert, David M
- Abstract
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.
- Publication
The Journal of cell biology, 2011, Vol 192, Issue 1, p29
- ISSN
1540-8140
- Publication type
Journal Article
- DOI
10.1083/jcb.201007111