Role of Escherichia coli DNA polymerase I in chromosomal DNA replication fidelity
Role of Escherichia coli DNA polymerase I in chromosomal DNA replication fidelity
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DOI：
10.1111/j.1365-2958.2009.06921.x
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发表时间：
2009-12-01
影响因子：
3.6
通讯作者：
Fijalkowska, Iwona J.
中科院分区：
文献类型：
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作者：
Makiela-Dzbenska, Karolina;Jaszczur, Malgorzata;Fijalkowska, Iwona J.
我们研究了大肠杆菌DNA聚合酶I在染色体复制保真度中的可能作用。这是通过用含有失活的3 '-> 5'外切核酸酶的polAexo变体取代染色体polA基因来完成的，所述外切核酸酶充当该酶的错误插入错误的校对器。使用该菌株，DNA复制过程中Pol I的活性可能随着细菌突变率的增加而被检测到。使用一系列定义的lacZ回复等位基因在两个方向上的染色体作为诱变标记，1.5至4倍的突变频率增加，观察。在一般情况下，这些增加是最大的紫胶取向有利于事件在滞后链DNA复制。进一步分析了这些效应在其他E.大肠杆菌DNA复制功能表明，这种polAexo增变因子的效果是最好的解释与其他错误产生的事件在复制叉相比，效果是加性的。没有证据表明Pol I参与聚合酶在Pol II、III和IV之间的分叉转换。相反，我们的数据表明，polAexo产生的额外错误是在滞后链中冈崎片段的成熟过程中产生的。
P>We have investigated the possible role of Escherichia coli DNA polymerase (Pol) I in chromosomal replication fidelity. This was done by substituting the chromosomal polA gene by the polAexo variant containing an inactivated 3'-> 5' exonuclease, which serves as a proofreader for this enzyme's misinsertion errors. Using this strain, activities of Pol I during DNA replication might be detectable as increases in the bacterial mutation rate. Using a series of defined lacZ reversion alleles in two orientations on the chromosome as markers for mutagenesis, 1.5- to 4-fold increases in mutant frequencies were observed. In general, these increases were largest for lac orientations favouring events during lagging strand DNA replication. Further analysis of these effects in strains affected in other E. coli DNA replication functions indicated that this polAexo mutator effect is best explained by an effect that is additive compared with other error-producing events at the replication fork. No evidence was found that Pol I participates in the polymerase switching between Pol II, III and IV at the fork. Instead, our data suggest that the additional errors produced by polAexo are created during the maturation of Okazaki fragments in the lagging strand.