收回:在活细胞中观察到的Okazaki片段合成期间的聚合酶交换
Giuseppe Lia1, Bénédicte Michel, Jean-François Allemand
1CNRS, Centre de Génétique Moléculaire, UPR3404, Gif-sur-Yvette F-91198, France. lia@cgm.cnrs-gif.fr
Science (New York, N.Y.)
|December 24, 2011
概括
研究人员观察到DNA聚合酶III (Pol III) 在E. coli复制分叉中的交换. 这表明在滞后链DNA合成过程中,每个Okazaki碎片都使用了一个新的Pol III.
科学领域:
- 分子生物学分子生物学
- 微生物学 微生物学
- 生物物理学的生物物理.
背景情况:
- DNA复制对于细胞分裂至关重要.
- 对于DNA复制元件的动力学还没有很好地理解.
- 大肠杆菌作为研究DNA复制的模型生物.
研究的目的:
- 研究活体大肠杆菌复制过程中DNA聚合酶作用的动力学.
- 为了观察复制叉上的聚合酶交换.
- 了解DNA聚合酶III (Pol III) 和单链DNA结合蛋白 (SSB) 在DNA合成中的作用.
主要方法:
- 使用单分子显微镜实时可视化DNA复制.
- 检测到单个Pol III分子的重复光爆发.
- 监测了与DNA结合的SSB水平的波动.
- 巧合分析被用来关联Pol III和SSB的动态.
主要成果:
- 单分子显微镜揭示了Pol III的重复光爆发,表明在复制分叉处的聚合酶交换.
- SSB波动与领先和落后链的不同合成速度相关.
- 巧合分析将Pol III和SSB波动与滞后链合成联系起来.
- 有证据表明,每一个奥卡扎基碎片都使用了一个新的Pol III.
结论:
- 这项研究提供了对DNA复制机械的动态性质的见解.
- 这些发现表明,在一个模型中,多个Pol III分子参与滞后链合成.
- 这些数据支持这样一个假设,即复原体中的第三个聚合酶致力于滞后链DNA合成,可能是每个Okazaki片段.
相关概念视频
03:01The Replisome
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
03:01The Replisome
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
01:31Proofreading
Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore, it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase Enzyme
Errors During Replication are Corrected by the DNA Polymerase Enzyme
01:43Proofreading
Overview
01:59Lagging Strand Synthesis
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
01:59Lagging Strand Synthesis
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...