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Sae2,Exo1とSgs1は,DNAの二重鎖断裂処理に協力しています
Eleni P Mimitou1, Lorraine S Symington
1Department of Microbiology, Columbia University Medical Center, 701 West 168th Street, New York, New York 10032, USA.
Nature
|September 23, 2008
まとめ
酵母菌のEXO1ヌクレアゼとSgs1ヘリカーゼは,DNAの二重鎖断裂 (DSB) を代替経路で処理する. Sae2は,初期のDSB処理に不可欠であり,Exo1とSgs1は,同類の再結合のための基板を生成するために,その後のステップで作用します.
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
- DNA修復 DNA修復する
背景:
- DNAの二重鎖断裂 (DSBs) は,修復のための同質再結合 (HR) を引き起こす.
- DSBの処理は5'-3'核分解分解により,Rad51.1.の単一鎖DNA (ssDNA) 基板を生成する.
- DSB処理に関与する重要な要因には,Mre11複合体,Sae2およびExo1.1が含まれています.
研究 の 目的:
- DSB処理における酵母Exo1ヌクレアゼとSgs1ヘリカーゼの役割を解明する.
- ホモログ性再結合のための基板を生成する際にSae2,Exo1,Sgs1の相互作用を調査する.
- ユカリオットDSBの末端解剖に伴うメカニズム的なステップを定義する.
主な方法:
- DSB処理因子 (Exo1,Sgs1,Sae2) を欠けている酵母変異体の遺伝子解析.
- 特定の突然変異の背景に蓄積するDNA修復中間物質の特徴.
- 同型再結合の効率に対する突然変異の影響の評価.
主要な成果:
- 酵母 Exo1 と Sgs1 は,DSB 処理のための並列の経路で機能します.
- exo1 sgs1 ダブルミュータントにおける部分的に切除されたDSB中間物質の蓄積.
- Sae2は,これらの中間物質を生成する最初の加工ステップに不可欠です.
- Sae2の欠如は,未処理のDSBの蓄積と,同質に依存する修復の失敗につながります.
結論:
- 同型再結合中のDSB処理は,2段階のメカニズムに従います.
- ステップ1:Mre11複合体とSae2は,オリゴヌクレオチドを取り除き,初期の中間物質を生成する.
- ステップ2: Exo1および/またはSgs1は,この中間物質を徹底的に切除して,Rad51結合およびHR開始のためのssDNAを生成します.
関連する概念動画
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Base Excision Repair
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...
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...

