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In vivo and in vitro Studies of Adaptor-clathrin Interaction
Published on: January 26, 2011
在单链DNA上进行渐进式AID催化细胞因子去胺,模拟体质突变
Phuong Pham1, Ronda Bransteitter, John Petruska
1Department of Biological Sciences, Hedco Molecular Biology Laboratories, University of Southern California, University Park, Los Angeles, California 90089-1340, USA.
Nature
|June 24, 2003
概括
激活诱导的cytidine除氨酶 (AID) 在单链DNA上将细胞素除氨化为 uracil,针对特定的WRC序列. 这种酶在个别的DNA链上进行多次除,解释了抗体基因突变的关键特征.
科学领域:
- 免疫学 免疫学 免疫学
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
背景情况:
- 激活诱导的cytidine deaminase (AID) 对于B细胞抗体多样化至关重要.
- 抗体类切换重组和体质突变 (SHM) 需要AID.
- 在单链DNA (ssDNA) 上,AID催化了细胞氨酸 (C) 转化为 uracil (U) 的去胺化.
研究的目的:
- 调查AID的体外催化活性和基质特异性.
- 为了阐明AID介导的DNA去胺化的机制.
- 为了将体外发现与SHM体内特征相关联.
主要方法:
- 在试验室内使用纯化的AID蛋白进行生化分析.
- 对C到U除产品的DNA序列的分析.
- 评估AID与ssDNA和DNA复合体的结合亲缘关系.
主要成果:
- 在ssDNA上,AID优先在5'WRC序列内去化C.
- 艾滋病在单个DNA链上进行多次除菌,而不是跨链跳跃.
- AID显示,非转录DNA链对转录DNA链的偏好是15倍.
结论:
- 在体外AID的催化活性和基质偏好解释了体内SHM的关键特征.
- 由于其正电荷驱动的AID与ssDNA的强度结合,促进了多重除.
- AID除的链偏好与SHM的转录依赖关系有关.
相关概念视频
Mismatch Repair
Overview
Mismatch Repair
Overview
Translesion DNA Polymerases
Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Homologous 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...
Mismatch 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
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Spontaneous and Induced Mutations
Spontaneous mutations arise infrequently during DNA replication due to errors in the process. A key factor behind these errors is tautomeric shifts in nitrogenous bases, where bases transition from keto to enol forms or amino to imino forms. This shift can alter base-pairing rules, leading to mutations. Additionally, reactive oxygen species (ROS) arising from aerobic metabolism can damage DNA, resulting in depurination (loss of a purine base) or depyrimidination (loss of a pyrimidine base).

