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ヒトの中性再結合酵素Dmc1は,ATPに依存した同型DNA鎖の交換を促進する
Michael G Sehorn1, Stefan Sigurdsson, Wendy Bussen
1Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA.
Nature
|May 28, 2004
まとめ
人間のDmc1 (hDmc1) タンパク質は,同質再結合の重要なプロセスであるDNA鎖交換を促進します. この活動は,ATPと複製因子A (RPA) に依存しており,メオシス中のDNA修復に不可欠です.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- バイオケミストリー バイオケミストリー
背景:
- ホモログな再結合は,DNA修復とゲノムの安定性にとって不可欠である.
- RecAタンパク質は,DNAペアリングと鎖交換を促進することによって,E. coliにおける同類の再結合を媒介する.
- ユカリオットはRad51とDmc1を使用し,Dmc1は特別にメオシスで機能します.
研究 の 目的:
- 人間のDmc1 (hDmc1) のDNA鎖交換能力を調査する.
- hDmc1媒介のDNA再結合開始のメカニズムを解明する.
- 媒介的過程におけるhDmc1の役割を理解する.
主な方法:
- hDmc1のDNA鎖交換活動を評価するためのインビトロアッセイ.
- 単一鎖DNA (ssDNA) 上でのhDmc1フィラメント形成の分析.
- hDmc1機能におけるATPと複製因子A (RPA) の必要性を調査する.
主要な成果:
- hDmc1は,長距離 (数千の塩基対) でペア化されたDNA基板間のDNA鎖交換を媒介する.
- このプロセスはATPを必要とし,RPAの存在によって著しく強化されます.
- 証拠によると,hDmc1はssDNAへの核化を介して再結合を開始し,螺旋状の核タンパク質フィラメントを形成する.
結論:
- hDmc1は,中性再結合に不可欠な重要なDNA鎖交換活動を有しています.
- hDmc1媒介の鎖交換は,中間分裂中のDNA二重鎖の断裂を修復するために不可欠です.
- この活動は,微分化の過程で染色体プロイジーを維持する上で重要な役割を果たしている可能性が高い.
関連する概念動画
Crossing Over
Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
Fixing Double-strand Breaks
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
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...
Gene Conversion
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
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...
Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...

