Mechanism of strand displacement synthesis by DNA replicative polymerases.
Mechanism of strand displacement synthesis by DNA replicative polymerases.
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DOI：
10.1093/nar/gks253
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发表时间：
2012-07
影响因子：
14.9
通讯作者：
Croquette V
中科院分区：
文献类型：
--
作者：
Manosas M;Spiering MM;Ding F;Bensimon D;Allemand JF;Benkovic SJ;Croquette V
复制型全酶表现出快速和连续的引物延伸DNA合成，但链置换DNA合成效率较低。我们研究了噬菌体T4和T7全酶在磁捕捉器操纵的DNA发夹底物上的引物延伸活性和链置换活性。全酶引物延伸活性受到外力的适度阻碍。相反，链置换活性被施加的力强烈地刺激；DNA聚合在高力时有利，而在低力时触发了进行性核酸外切酶活性。我们认为，全酶上游的DNA分叉产生了一个回归压力，从而抑制了全酶的聚合驱动向前运动。这种抑制是由于聚合活性部位内的模板链扭曲而产生的，从而将平衡转变为DNA-蛋白质核酸外切酶构象。我们的结论是，分叉回归压力导致的全酶停滞是复制聚合酶低效链置换合成特性的基础。由此产生的过程性核酸外切酶活性可能与复制体解离有关，以将停滞的复制叉重置为对称状态。我们的发现为单分子DNA测序提供了有趣的应用。
Replicative holoenzymes exhibit rapid and processive primer extension DNA synthesis, but inefficient strand displacement DNA synthesis. We investigated the bacteriophage T4 and T7 holoenzymes primer extension activity and strand displacement activity on a DNA hairpin substrate manipulated by a magnetic trap. Holoenzyme primer extension activity is moderately hindered by the applied force. In contrast, the strand displacement activity is strongly stimulated by the applied force; DNA polymerization is favoured at high force, while a processive exonuclease activity is triggered at low force. We propose that the DNA fork upstream of the holoenzyme generates a regression pressure which inhibits the polymerization-driven forward motion of the holoenzyme. The inhibition is generated by the distortion of the template strand within the polymerization active site thereby shifting the equilibrium to a DNA-protein exonuclease conformation. We conclude that stalling of the holoenzyme induced by the fork regression pressure is the basis for the inefficient strand displacement synthesis characteristic of replicative polymerases. The resulting processive exonuclease activity may be relevant in replisome disassembly to reset a stalled replication fork to a symmetrical situation. Our findings offer interesting applications for single-molecule DNA sequencing.
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影响因子：
64.5
作者：
Franklin, MC;Wang, JM;Steitz, TA
通讯作者：
Steitz, TA
影响因子：
2.9
作者：
LADUCA, RJ;FAY, PJ;BAMBARA, RA
通讯作者：
BAMBARA, RA
影响因子：
9.2
作者：
KABOORD, BF;BENKOVIC, SJ
通讯作者：
BENKOVIC, SJ
DOI：
10.1073/pnas.0709793104
发表时间：
2007-12-11
影响因子：
11.1
作者：
Lionnet, Timothee;Spiering, Michelle M.;Croquette, Vincent
通讯作者：
Croquette, Vincent
影响因子：
3.4
作者：
Ribeck, Noah;Kaplan, Daniel L.;Saleh, Omar A.
通讯作者：
Saleh, Omar A.