大肠杆菌外核酶VII的结构
Chuan Liu1, Glenn Hauk1, Qianyun Yan1
1Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
概括
外核酶VII (ExoVII) 是一种细菌核酶. Cryo-EM揭示了其状结构,其中DNA处理由硬质访问控制,这表明DNA修复的进化趋同.
科学领域:
- 结构生物学 结构生物学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- 外核酶VII (ExoVII) 是一种参与DNA处理和修复的细菌核酶.
- 它的结构和功能关系在很大程度上仍未定义.
- ExoVII是由xseA和xseB基因编码的.
研究的目的:
- 使用冷电子显微镜 (cryoEM) 确定大肠杆菌ExoVII全息复合物的结构.
- 为了阐明EXOVII的结构-功能关系.
- 了解基质选择性和DNA修复的机制.
主要方法:
- 使用冷电子显微镜 (cryoEM) 确定了 ExoVII 全光复合体的结构.
- 进行了生物化学研究,以调查基质选择性和DNA结合.
- 结构分析的重点是XseA和XseB子单位的安排.
主要成果:
- 大肠杆菌ExoVII形成了一个高度延长的,状的八角体 (XseA4·XseB24).
- 该综合体具有XseA催化域的独特排列,这些域被集中隔离.
- 基质的接入是经过固体控制的,四聚体解离是由DNA结合引发的.
结论:
- ExoVII的架构组织通过硬质访问控制基质选择性.
- ExoVII的结构让人想起其他DNA修复核酶,这表明了融合进化.
- 了解 ExoVII 结构为细菌 DNA 修复机制提供了洞察力,特别是 DNA-蛋白质交叉链接.
更多相关视频
11:09Online Size-exclusion and Ion-exchange Chromatography on a SAXS Beamline
Published on: January 5, 2017
17.3K
06:10A Fluorescence-based Exonuclease Assay to Characterize DmWRNexo, Orthologue of Human Progeroid WRN Exonuclease, and Its Application to Other Nucleases
Published on: December 23, 2013
5.4K
相关概念视频
01:38Nucleotide Excision Repair
3.5K
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...
3.5K
01:20Mismatch Repair
4.8K
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...
4.8K
01:54Base Excision Repair
22.3K
One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and strand breakage during replication. This type of damage causes minimal change to the DNA double helix structure and can be repaired by the base excision repair (BER) pathways. BER corrects damaged DNA sequences by removing the damaged base and restoring the original base sequence using the complementary strand as a template.
The first step of...
The first step of...
22.3K
03:01The Replisome
33.5K
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 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...
33.5K
00:55DNA Helicases
21.3K
DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
21.3K
02:31Homologous Recombination
50.5K
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...
50.5K