一种单一的氨基酸控制了DINB DNA聚合酶在受损模板上的增强活性
Daniel F Jarosz1, Veronica G Godoy, James C Delaney
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nature
|January 13, 2006
概括
保存的DNA聚合酶DinB精确地绕过了N2-deoxyguanosine (dG) 的DNA添加物. 这种病变绕道比复制未受损的DNA更有效,这解释了DinB的存在.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 通过Y家族DNA聚合酶的转载合成 (TLS) 对DNA损伤耐受性至关重要.
- 作为一个普遍保留的Y-家族聚合酶,DinB的生物学作用尚不清楚.
- 某些DNA损伤剂在脱氧氨酸 (dG) 的N2位置形成添加物.
研究的目的:
- 调查大肠杆菌DinB在DNA损伤耐受性中的作用.
- 为了确定DinB在绕过N2-脱氧氨酸 (dG) 导入中的作用.
- 阐明DinB介导的TLS的机制和特异性.
主要方法:
- 评估了dinB基因对破坏DNA的抗体的要求.
- 测量了DinB和DNA聚合酶卡帕的催化能力,用于在N2-furfuryl-dG和未损坏的dG对面插入deoxycytidine (dC).
- 利用位点定向突变发生来改变DinB及其同类Dbh.中的"体门"残留物.
主要成果:
- 大肠杆菌dinB对于对特定的N2-dG添加物形成剂的耐药性至关重要.
- DinB (DNA聚合酶IV) 准确地在N2-furfuryl-dG添加物上执行TLS.
- 丁B和DNA聚合酶卡帕对插入dC与N2-furfuryl-dG相对应的催化能力明显高于未受损的dG.
- 在DinB和Dbh中突变"体门"残留物将病变绕道从未损坏的模板复制解开.
- 通过DinB的损伤绕道比在未受损的DNA模板上的合成更有效.
结论:
- DinB及其正义学家专注于在无处不在的N2-dG附加物上准确的TLS.
- 酶特异性对于病变绕道可能涉及病变诱导的形状变化.
- DinB的保存性质表明它在所有生命领域的DNA修复中发挥着基本的生物学作用.
相关概念视频
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...
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...
DNA Damage can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
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...
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
DNA Damage Can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...


