Evidence from mutational specificity studies that yeast DNA polymerases δ and ε replicate different DNA strands at an intracellular replication fork
Evidence from mutational specificity studies that yeast DNA polymerases δ and ε replicate different DNA strands at an intracellular replication fork
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DOI：
10.1006/jmbi.2000.3744
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发表时间：
2000-06-02
影响因子：
5.6
通讯作者：
Kunz, BA
中科院分区：
文献类型：
--
作者：
Karthikeyan, R;Vonarx, EJ;Kunz, BA
虽然聚合酶delta和delta是真核细胞中DNA复制所必需的，但每个聚合酶是否在单独的模板链上起作用仍然是一个悬而未决的问题。为了开始研究两种聚合酶的相对细胞内作用，我们使用了质粒携带的酵母tRNA基因和酵母菌株，这些酵母菌株是由于DNA聚合酶delta或delta消除校对而产生的突变体。反转的tRNA基因改变的前导链和滞后链模板的序列改变了两个增变聚合酶的特异性，但在相反的方向。也就是说，聚合酶δ突变子与tRNA基因在一个方向上的特异性与聚合酶δ突变子与tRNA基因在另一个方向上的特异性具有相似性，反之亦然。我们还获得了与基因取向一致的结果，该基因取向对野生型菌株中发生的复制错误的错配校正具有微小影响。然而，这些数据表明，无论是这种效果，也没有差异复制保真度是负责的校正缺陷突变体基因倒位后观察到的突变特异性变化。总的来说，这些数据表明聚合酶delta和delta在反转tRNA基因时遇到不同的模板序列，因此在质粒DNA复制叉处复制相反的链。(C)北京大学出版社.
Although polymerases delta and epsilon are required for DNA replication in eukaryotic cells, whether each polymerase functions on a separate template strand remains an open question. To begin examining the relative intracellular roles of the two polymerases, we used a plasmid-borne yeast tRNA gene and yeast strains that are mutators due to the elimination of proofreading by DNA polymerases delta or epsilon. Inversion of the tRNA gene to change the sequence of the leading and lagging strand templates altered the specificities of both mutator polymerases, but in opposite directions. That is, the specificity of the polymerase delta mutator with the tRNA gene in one orientation bore similarities to the specificity of the polymerase epsilon mutator with the tRNA gene in the other orientation, and vice versa. We also obtained results consistent with gene orientation having a minor influence on mismatch correction of replication errors occurring in a wild-type strain. However, the data suggest that neither this effect nor differential replication fidelity was responsible for the mutational specificity changes observed in the proofreading-deficient mutants upon gene inversion. Collectively, the data argue that polymerases delta and epsilon each encounter a different template sequence upon inversion of the tRNA gene, and so replicate opposite strands at the plasmid DNA replication fork.(C) 2000 Academic Press.