遅れた鎖の複製の説明は,ポリメラーゼがDNAのスライディングクランプの間を飛び回るというものです
P T Stukenberg1, J Turner, M O'Donnell
1Microbiology Department, Cornell University Medical College, New York, New York 10021.
Cell
|September 9, 1994
まとめ
DNAポリメラーゼIIIホロ酵素は,オカザキの断片を部分的に分解して再組みすることで迅速に合成します. この新しいメカニズムは,酵素がDNAテンプレートとベータクランプの間で効率的にサイクルすることを可能にします.
科学分野:
- 分子生物学は分子生物学である.
- バイオケミストリー バイオケミストリー
- 遺伝学 遺伝学とは
背景:
- DNAポリメラーゼIIIホロ酵素,E. coliの複製酵素は,DNA複製に不可欠である.
- この酵素は,環状のベータスライディングクランプによってDNAに固定されます.
- 効率的なDNA複製には,ポリメラーゼが繰り返しDNAを結合して放出することが必要であり,特に遅滞する鎖のオカザキ断片合成には必要である.
研究 の 目的:
- DNAポリメラーゼIIIホロ酵素が遅延鎖合成中にDNAをオン・オフするメカニズムを解明する.
- ポリメラーゼが,多数のオカザキ断片の合成のための急速なターンオーバーをどのように管理するかを理解するために.
主な方法:
- この研究では,ポリメラーゼ-クランプ-DNAの相互作用を観察するために,試験管内生化学的測定と潜在的に構造生物学的な技術が関与している可能性が高い.
- マルチサブユニットDNAポリメラーゼIIIホロ酵素の分解・再組みプロセスの分析.
主要な成果:
- DNAポリメラーゼIIIホロ酵素は,DNAテンプレート間の移行に部分分解と再組みを伴う新しいメカニズムを使用しています.
- ポリメラーゼはテンプレートを完了するとベータクランプから解離し,DNAから分離し,別のプライムされた場所に新しいベータクランプと結合します.
- ベータクランプは,ポリメラーゼが解離した後もDNAに結合し,潜在的に他の細胞機械の調整点として機能します.
結論:
- DNAポリメラーゼIIIホロ酵素は,効率的な複製サイクルのために,ダイナミックな解離再組み戦略を採用しています.
- このメカニズムは,遅滞した鎖のオカザキの断片の迅速かつ継続的なDNA合成を促進します.
- ポリメラーゼ放出後のベータクランプの解離は,他のDNA代謝プロセスとの複製の調整における役割を示唆しています.
関連する概念動画
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02:37Restarting Stalled Replication Forks
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01:59Lagging Strand Synthesis
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
03:01The Replisome
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...