誤った配列のDNAを安定させるというDNAポールの驚くべき能力です
Meredith C Foley1, Victoria A Padow, Tamar Schlick
1Department of Chemistry and Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, USA.
Journal of the American Chemical Society
|September 9, 2010
まとめ
DNAポリメラーゼラムダ (pol λ) は,不整列DNAを安定させる有利な静電相互作用により,ポリメラーゼβ (pol β) よりも多くのデリレーションエラーを引き起こす. pol λの特定の残留物は,pol βとは異なり,DNAの不整列を安定させるネットワークを作り出します.
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ポリメラーゼは,複製と修復の間にゲノムの安定性にとって極めて重要です.
- 削除エラーを含むポリメラーゼ固有のエラー率が観察されています.
- DNAポリメラーゼラムダ (pol λ) は,DNAポリメラーゼベータ (pol β) よりも単塩基切除の傾向が高い.
研究 の 目的:
- DNAポリメラーゼlambda (pol λ) が,DNAポリメラーゼβ (pol β) と比較して,削除エラーの傾向が増加していることの分子基礎を調査する.
- 誤った配列のDNA構造の安定化におけるタンパク質/DNAの静電相互作用の役割を明らかにする.
- 特定の残留物とその相互作用を特定し,pol λにおけるDNA不整列の安定化に寄与する.
主な方法:
- インシリコ分子動力学シミュレーション.
- 無料エネルギーの分析.
- pol λ (例えば,Lys544,Arg538,Lys521,Arg517,Arg514) の主要残留物のサイト指向型変異およびその後のエネルギー分析.
主要な成果:
- Pol λは,整合したDNAと比較して,不整合のDNAの安定性が高いことを示しています.
- ポリ λにおけるLys544の電荷は,DNA不整列の安定化に極めて重要です.
- 親指の残留物 (Arg538,Lys521,Arg517,Arg514) のネットワークは,pol λ の不整列DNAを集団的に安定させ,これはpol β にない効果である.
- 変異分析により,これらの残留物の総安定効果が確認されました.
結論:
- pol λにおける超螺旋核酸の周りの好ましい静電相互作用は,そのより高い削除エラー率に寄与する.
- 不整列DNAに対するPol λのユニークな安定化ネットワークは,非同類の末端結合のような修復経路のための進化的適応である可能性があります.
- これらの発見は,ポリメラーゼの忠誠性とDNA修復メカニズムについての洞察を提供します.
関連する概念動画
Translesion DNA Polymerases
Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
Proofreading
Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore, it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase Enzyme
Errors During Replication are Corrected by the DNA Polymerase Enzyme
Proofreading
Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA polymerase has a higher affinity for the correct base to ensure fidelity in DNA replication. The DNA polymerase furthermore proofreads during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.Errors during Replication Are Corrected by the DNA Polymerase EnzymeGenomic DNA is synthesized in...
Restarting 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...
DNA Topoisomerases
Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
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...


