The capacity of origins to load MCM establishes replication timing patterns.
The capacity of origins to load MCM establishes replication timing patterns.
复制标题
起点加载MCM的能力建立了复制定时模式。
DOI：
10.1371/journal.pgen.1009467
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发表时间：
2021-03
期刊：
影响因子：
4.5
通讯作者：
Rhind N
中科院分区：
文献类型：
--
作者：
Dukaj L;Rhind N
MCM复制解旋酶在复制起点的装载是在所有真核生物中先于DNA复制的高度调节的过程。MCM的化学计量装载在原点已被提出是一个关键的决定因素，当这些原点开始复制在S阶段。然而，MCM装载化学计量的全基因组调节及其对复制时机的直接影响仍不清楚。为了研究为什么一些起源负载更多的MCM比别人，我们扰动MCM水平在芽殖酵母细胞，并首次直接测量MCM水平和复制时间在同一个实验。MCM水平的减少，通过降解的Mcm4，其中的六个专性组件的MCM复合物，减缓通过S期的进展和增加的敏感性复制应力。MCM水平的减少也导致了G1期间在起源处的差异负载，揭示了对MCM减少敏感的起源和其他不敏感的起源。在正常条件下，敏感的起源装载较少的MCM，并与较弱的招募起源识别复合物（ORC）的能力相关。此外，减少MCM加载在特定的复制起点导致延迟在S期期间的复制。相比之下，MCM的过表达对细胞周期进程、起源处的相对MCM水平或复制时机没有影响，这表明在最佳生长条件下，细胞MCM水平对MCM负载没有限制。我们的研究结果支持一个模型，在该模型中，装载能力的起源是MCM的化学计量在野生型细胞的主要决定因素，但化学计量控制的起源的能力，招募ORC和竞争MCM时，MCM成为限制。复杂真核生物基因组的协调复制主要在复制起始水平受到调控。因此，如何在时间和空间中调节启动是一个活跃的研究领域。一个主要的假设是，MCM，复制解旋酶，在复制起点的化学计量是一个重要的决定因素的起始时间。然而，MCM的化学计量在起源是如何调节是未知的。我们测试了两个假设的机制，MCM化学计量的控制：原产地的能力，其中MCM的化学计量是由不同的能力，个别原产地加载MCM，和ORC的活动，其中MCM的化学计量是由不同的活动的ORC，MCM的加载器，在个别原产地调节。我们发现，这两种机制都与我们的数据不一致，但这两种机制的混合是。
Loading of the MCM replicative helicase at origins of replication is a highly regulated process that precedes DNA replication in all eukaryotes. The stoichiometry of MCM loaded at origins has been proposed to be a key determinant of when those origins initiate replication during S phase. Nevertheless, the genome-wide regulation of MCM loading stoichiometry and its direct effect on replication timing remain unclear. In order to investigate why some origins load more MCM than others, we perturbed MCM levels in budding yeast cells and, for the first time, directly measured MCM levels and replication timing in the same experiment. Reduction of MCM levels through degradation of Mcm4, one of the six obligate components of the MCM complex, slowed progression through S phase and increased sensitivity to replication stress. Reduction of MCM levels also led to differential loading at origins during G1, revealing origins that are sensitive to reductions in MCM and others that are not. Sensitive origins loaded less MCM under normal conditions and correlated with a weak ability to recruit the origin recognition complex (ORC). Moreover, reduction of MCM loading at specific origins of replication led to a delay in their replication during S phase. In contrast, overexpression of MCM had no effects on cell cycle progression, relative MCM levels at origins, or replication timing, suggesting that, under optimal growth conditions, cellular MCM levels are not limiting for MCM loading. Our results support a model in which the loading capacity of origins is the primary determinant of MCM stoichiometry in wild-type cells, but that stoichiometry is controlled by origins’ ability to recruit ORC and compete for MCM when MCM becomes limiting. The coordinated replication of complex eukaryotic genomes is primarily regulated at the level of replication initiation. Therefore, how initiation is regulated in time and space is an active field of research. A leading hypothesis is that the stoichiometry of MCM, the replicative helicase, at replication origins is a significant determinant of initiation timing. However, how MCM stoichiometry at origins is regulated is unknown. We tested two hypothetical mechanisms for the control of MCM stoichiometry: Origin capacity, in which MCM stoichiometry is constrained by the varying capacity of individual origins to load MCM, and ORC activity, in which MCM stoichiometry is regulated by the varying activity of ORC, the MCM loader, at individual origins. We find that neither mechanism is consistent with our data, but that a hybrid of the two mechanisms is.
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影响因子：
3.3
作者：
Bell SP;Labib K
通讯作者：
Labib K
影响因子：
10.5
作者：
Eaton, Matthew L.;Galani, Kyriaki;MacAlpine, David M.
通讯作者：
MacAlpine, David M.
DOI：
10.1073/pnas.94.11.5611
发表时间：
1997-05-27
影响因子：
11.1
作者：
Donovan, S;Harwood, J;Diffley, JFX
通讯作者：
Diffley, JFX
影响因子：
4.8
作者：
Edwards, MC;Tutter, AV;Walter, JC
通讯作者：
Walter, JC
影响因子：
10.5
作者：
Ge, Xin Quan;Jackson, Dean A;Blow, J Julian
通讯作者：
Blow, J Julian