Rad51-mediated double-strand break repair and mismatch correction of divergent substrates (RAD51-mediated

Ranjith Anand¹, Annette Beach¹, Kevin Li¹

¹Rosenstiel Basic Medical Sciences Research Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110, USA.

Nature

|April 14, 2017

まとめ

芽生える酵母Rad51リコンビネーゼは,同種のDNAを見つけることでDNA修復を容易にする. Rad51はこれまで考えられていたよりも多くの不一致を許容し,DNAの二重鎖の断裂修復を助長する.

科学分野:

分子生物学
遺伝学
生物化学

背景:

Rad51リコンビネーゼは同類リコンビネーションとDNA二重鎖破裂 (DSB) の修復に不可欠です.
実験室内での研究は,Rad51のDNAホモロジー検索の厳密さを示唆しているが,体内での行動はあまり理解されていない.

研究の目的:

Rad51 ホモロジー検索のインビボの厳しさと,ブレイク誘発複製中のDNA配列の不一致に対する敏感性を調査する.
ホメオログ的再結合における不一致修復タンパク質,特にMsh2の役割を決定する.

主な方法:

単一塩基対不一致の密度が異なるSaccharomyces cerevisiaeにおけるRad51依存的断裂誘発複製の分析
不一致した基板を拒絶するMsh2の役割に対する3'突起の非同型尾の影響を調査する.
鎖侵入ヘテロデュプレックスDNAにおける不一致補正の極性およびタンパク質依存性を評価する.

主要な成果:

In vivoでは,Rad51媒介によるブレイク誘発複製は,連続した6~8の塩基対の不一致でも発生し,in vitroの要求に反する.
Msh2は,DSB端に3'突起の非同類の尾がある場合にのみ,同類の再結合を防止した.
ヘテロデュプレックスDNAの不一致修正は極性であり,DSB末端を好み,主にDNAポリメラーゼ-δ校正活動に依存した.

結論:

芽生える酵母Rad51は,in vivoでは,in vitro研究から推測されたよりも,DNA配列の不一致に対してより高い耐性を示しています.
不一致した基板を拒絶するMsh2の機能は文脈に依存し,非同型尾の存在に影響する.
再結合における不一致修復は,DNAポリメラーゼ-δおよびMsh2,Mlh1,およびExo1のような他の修復タンパク質によって影響される極性プロセスである.

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