不间断的MCM2-7功能是DNA复制叉进展所需的
K Labib1, J A Tercero, J F Diffley
1Imperial Cancer Research Fund Clare Hall Laboratories, South Mimms, Hertfordshire, EN6 3LD, UK.
Science (New York, N.Y.)
|June 2, 2000
概括
微染色体维护 (MCM) 复合体对于DNA复制至关重要,对于延长酵母中的复制分叉至关重要. 这一发现揭示了MCM.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 在真核细胞DNA复制延长中,DNA螺旋酶的作用仍然在很大程度上是未知的.
- 微染色体维护 (MCM) 蛋白质复合体具有DNA酶活性,但主要与复制启动有关.
研究的目的:
- 为了研究MCM复合体在真核生物DNA复制的延长阶段的功能.
- 为了确定MCM复合体是否需要超越DNA复制的启动步骤.
主要方法:
- 利用一种改进的方法在Saccharomyces cerevisiae中构建条件降解突变.
- 在DNA复制开始后耗尽的MCM蛋白质,观察对分叉进展的影响.
主要成果:
- 启动后MCMs的耗尽导致了酵母复制叉进展的不可逆转阻断.
- 证明MCM复合物,就像细菌和病毒螺旋酶一样,在启动之前被加载,对延长至关重要.
- 证明将MCM负载限制在G(1) 阶段,确保复制只发生一次细胞周期.
结论:
- MCM复合体对于真核细胞DNA复制的延长阶段至关重要,而不仅仅是启动.
- MCM负载调节通过允许每个细胞周期只有一轮,确保了DNA复制的忠实性.
相关概念视频
01:02The DNA Replication Fork
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
02:31Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
01:02The DNA Replication Fork
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
02:31Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...