The p12 subunit of human polymerase delta modulates the rate and fidelity of DNA synthesis.
The p12 subunit of human polymerase delta modulates the rate and fidelity of DNA synthesis.
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DOI：
10.1021/bi100042b
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发表时间：
2010-05-04
期刊：
影响因子：
2.9
通讯作者：
Frick DN
中科院分区：
文献类型：
--
作者：
Meng X;Zhou Y;Lee EY;Lee MY;Frick DN
本研究通过比较四个亚基复合体、缺乏p12的三个亚基复合体和各自缺乏校对核酸外切酶活性的定点突变体催化的δ合成和降解动力学，探讨了p12亚基在人类DNA聚合酶δ(PolDNA)全酶功能中的作用。结果表明，p12通过Polδ调节DNA合成的速度和保真度。这四个复合体都在一个快速的爆发阶段和一个较慢的、更线性的阶段合成DNA。在p12存在的情况下，DNA合成的爆发速度大约快5倍，而酶对其DNA和dNTP底物的亲和力似乎没有变化。P12亚基通过调节校对3‘到5’核酸外切酶的活性来改变POLδ的保真度。在没有p12的情况下，POLδ更有可能校对dna合成，因为它切割单链dna的速度是p12的两倍，将错配的dna从聚合酶转移到核酸外切酶位点的速度是p12的9倍。在没有p12的情况下，POLδ延伸错配的引物的速度也慢了3倍。综上所述，p12对PolDNA施加的变化可以调节其δ合成的保真度。P12的丢失发生在细胞中，当暴露于dna损伤剂时，它将Pollδ转化为一种具有更强的校对能力的形式。
This study examines the role of the p12 subunit in the function of the human DNA polymerase δ (Pol δ) holoenzyme by comparing the kinetics of DNA synthesis and degradation catalyzed by the four subunit complex, the three subunit complex lacking p12, and site directed mutants of each lacking proofreading exonuclease activity. Results show that p12 modulates the rate and fidelity of DNA synthesis by Pol δ. All four complexes synthesize DNA in a rapid burst phase and a slower, more linear phase. In the presence of p12, the burst rates of DNA synthesis are about five times faster, while the affinity of the enzyme for its DNA and dNTP substrates appears unchanged. The p12 subunit alters Pol δ fidelity by modulating the proofreading 3′ to 5′ exonuclease activity. In the absence of p12, Pol δ is more likely to proofread DNA synthesis because it cleaves single-stranded DNA twice as fast and transfers mismatched DNA from the polymerase to the exonuclease sites 9 times faster. Pol δ also extends mismatched primers 3 times more slowly in the absence of p12. Taken together, the changes that p12 exerts on Pol δ are ones that can modulate its fidelity of DNA synthesis. The loss of p12, which occurs in cells upon exposure to DNA damaging agents, converts Pol δ to a form that has an increased capacity for proofreading.
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影响因子：
14.9
作者：
Meng X;Zhou Y;Zhang S;Lee EY;Frick DN;Lee MY
通讯作者：
Lee MY
影响因子：
19
作者：
Kunkel, Thomas A.;Burgers, Peter M.
通讯作者：
Burgers, Peter M.
影响因子：
64.5
作者：
Franklin, MC;Wang, JM;Steitz, TA
通讯作者：
Steitz, TA
影响因子：
4.8
作者：
Liu, L;Mo, JY;Lee, MYWT
通讯作者：
Lee, MYWT
影响因子：
2.9
作者：
BYRNES, JJ;DOWNEY, KM;SO, AG
通讯作者：
SO, AG