在净化系统中重建5'-定向的人类不匹配修复
Yanbin Zhang1, Fenghua Yuan, Steven R Presnell
1Graduate Center for Toxicology and Markey Cancer Center, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA.
Cell
|September 7, 2005
概括
人类不匹配的修复被使用纯化的蛋白质重建. MutSbeta有效地修复插入/删除不匹配,而MutLalpha控制EXO1切除,这表明了一个协调的修复模型.
科学领域:
- 分子生物学分子生物学
- DNA 修复机制的修复机制
- 人类遗传学 人类遗传学
背景情况:
- 对于基因组的稳定性来说,DNA复制的真实性至关重要.
- 在DNA复制过程中产生的不匹配需要有效的修复途径.
- 人类不匹配修复 (MMR) 纠正基底不匹配和插入/删除循环.
研究的目的:
- 用纯化的人类蛋白质重建一个5'-nick-directed不匹配修复系统.
- 阐明MutSalpha,MutSbeta和MutLalpha在不匹配修复中的特定作用.
- 了解MMR蛋白在切除和终止中的协调作用.
主要方法:
- 人类不匹配修复系统与净化蛋白质的重组:MutSalpha,MutSbeta,MutLalpha,RPA,EXO1,HMGB1,PCNA,RFC,聚合酶三角酶和酶I.
- 在体外测试以评估基基不匹配和插入/删除不匹配的修复.
- 分析单个蛋白质和复合体在切割和终止过程中的作用.
主要成果:
- 与MutSalpha相比,MutSbeta在处理插入/删除错误的过程中表现出更高的效率.
- MutLalpha显著降低了EXO1的过程性,并在不匹配部位终止了切除.
- RPA和HMGB1在刺激EXO1催化切除中发挥着互补的作用,RPA也促进了切除.
- 有效的修复需要多个MutSalpha-MutLalpha复合体.
结论:
- 一个重建的人类不匹配修复系统突出了MutSbeta和MutSalpha的不同作用.
- 穆特拉尔法作为一个关键的调节器,控制EXO1中介切除的程度.
- 这些发现支持了人类不匹配修复中的协调启动和终止模型.
相关概念视频
01:36Mismatch Repair
Overview
01:08Nucleotide Excision Repair
Overview
01:36Mismatch Repair
Overview
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...
01:38Nucleotide Excision Repair
DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
01:20Mismatch Repair
Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...