Unequal fidelity of leading strand and lagging strand DNA replication on the Escherichia coli chromosome
Unequal fidelity of leading strand and lagging strand DNA replication on the Escherichia coli chromosome
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DOI：
10.1073/pnas.95.17.10020
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发表时间：
1998-08-18
影响因子：
11.1
通讯作者：
Schaaper, RM
中科院分区：
文献类型：
--
作者：
Fijalkowska, IJ;Jonczyk, P;Schaaper, RM
我们研究了大肠杆菌染色体 DNA 复制过程中两条 DNA 链是否可以以不同的精度复制的问题。这种差异复制保真度的可能性源于两条链中不同的复制模式，一条链（前导链）连续合成，另一条链（滞后链）以短冈崎片段的形式不连续地合成。我们构建了一系列 lacZ 菌株，其中 lac 操纵子以相对于染色体复制起点 oriC 的两个可能方向插入细菌染色体中。在突变反映复制错误的条件下，对两个方向的 lac 回复频率的测量揭示了两个方向之间的可变性的明显差异。由于基因倒位导致前导链和滞后链的转换，这些发现表明前导链和滞后链复制具有不同的保真度。对每个特定碱基对替换背后可能的错配的分析表明，大肠杆菌染色体上的滞后链复制可能比前导链复制更准确。
We have investigated the question whether during chromosomal DNA replication in Escherichia coli the two DNA strands may be replicated with differential accuracy. This possibility of differential replication fidelity arises from the distinct modes of replication in the two strands, one strand (the leading strand) being synthesized continuously, the other (the lagging strand) discontinuously in the form of short Okazaki fragments. We have constructed a series of lacZ strains in which the lac operon is inserted into the bacterial chromosome in the two possible orientations with regard to the chromosomal replication origin oriC. Measurement of lac reversion frequencies for the two orientations, under conditions in which mutations reflect replication errors, revealed distinct differences in mutability between the two orientations. As gene inversion causes a switching of leading and lagging strands, these findings indicate that leading and lagging strand replication have differential fidelity. Analysis of the possible mispairs underlying each specific base pair substitution suggests that the lagging strand replication on the E. coli chromosome may be more accurate than leading strand replication.