MフェーズとSフェーズにおけるORCの役割
1Division of Genetics, University of California at Berkeley, 401 Barker Hall, Berkeley, CA 94720, USA.
Science (New York, N.Y.)
|March 28, 1998
まとめ
起源認識複合体 (ORC) は,酵母におけるDNA複製の開始に極めて重要です. 変異したOrc5pまたはOrc2pは,機能的なORCが存在する場合でも,複製の起源を阻害することによって,細胞サイクル進行を圧倒的にブロックすることができます.
科学分野:
- 分子生物学は分子生物学である.
- 細胞サイクル規則 細胞サイクル規則
- イースト遺伝学 イースト遺伝学
背景:
- 起源認識複合体 (ORC) は,Saccharomyces cerevisiae.でDNA複製を開始する.
- ORCの組み立てと活性化は,細胞サイクル中に厳格に規制され,MとSの末期に発生します.
- Orc5pのような特定のORCサブユニットは,異なる細胞サイクル移行 (G1/SおよびM段階) で重要な役割を果たします.
研究 の 目的:
- 起源認識複合体 (ORC) のOrc5pサブユニットの細胞サイクル役割を調査する.
- ORCサブユニット,特にorc5-1およびorc2アレルにおける温度感受性変異に関連するフェノタイプを特徴付ける.
- 特定のORC変異体で観察された支配的な細胞サイクル停止の背後にあるメカニズムを決定する.
主な方法:
- 温度に敏感な酵母変異体 (orc5-1) を利用して,ORC機能を研究した.
- 細胞サイクルの停止を正確にタイミング化するために,細胞同期技術 (M相ブロックと解放) を採用した.
- 野生型のOrc5pを導入し,orc2アレルとの遺伝的相互作用を評価することによって,突然変異フェノタイプの優位性を分析しました.
主要な成果:
- 温度に敏感なオーク5-1変異体は,初期同期によって異なる細胞サイクル停止フェノタイプを示した:アシンクロン細胞の初期M相,M相同期細胞のG1/S境界.
- orc5-1によって引き起こされたG1/S停止は,G1.1の間に野生型のOrc5pを追加することによって救われませんでした.
- orc2 と orc5 の突然変異は,細胞サイクル進行を抑制し,核に局限された支配的な負の効果を示した.
結論:
- Orc5pは,酵母におけるG1/Sと早期M相の両方の進行に不可欠です.
- 変異したORC複合体,特にOrc2pとOrc5pを含む複合体は,DNA複製の開始に支配的な阻害を行なうことができます.
- 核の局所化された支配的阻害は,変異したORC複合体が染色体上の野生型のORCの機能に干渉し,機能的起源で複製の開始をブロックすることを示唆しています.
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02:38S-Cdk Initiates DNA Replication
The cell cycle is a series of events leading to DNA duplication followed by the division of cell content to form two daughter cells. The cell cycle progresses in four stages—the cell increases in size (gap 1 or G1-phase), duplicates its DNA (synthesis or S-phase), prepares to divide (gap 2 or G2-phase), and divides (mitosis or M-phase).
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
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In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
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Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
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