Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden.
Nucleic Acids Res. 2019 May 7;47(8):3986-3995. doi: 10.1093/nar/gkz048.
The four B-family DNA polymerases α, δ, ϵ and ζ cooperate to accurately replicate the eukaryotic nuclear genome. Here, we report that a Saccharomyces cerevisiae strain encoding the pol2-16 mutation that lacks Pol ϵ's polymerase and exonuclease activities has increased dNTP concentrations and an increased mutation rate at the CAN1 locus compared to wild type yeast. About half of this mutagenesis disappears upon deleting the REV3 gene encoding the catalytic subunit of Pol ζ. The remaining, still strong, mutator phenotype is synergistically elevated in an msh6Δ strain and has a mutation spectrum characteristic of mistakes made by Pol δ. The results support a model wherein slow-moving replication forks caused by the lack of Pol ϵ's catalytic domains result in greater involvement of mutagenic DNA synthesis by Pol ζ as well as diminished proofreading by Pol δ during replication.
B 族 DNA 聚合酶 α、δ、ϵ 和 ζ 四种协同作用，准确复制真核生物核基因组。在这里，我们报告说，一种编码 pol2-16 突变的酿酒酵母菌株缺乏 Pol ϵ 的聚合酶和外切酶活性，与野生型酵母相比，CAN1 基因座的 dNTP 浓度增加，突变率增加。大约一半的诱变作用在删除编码 Pol ζ 催化亚基的 REV3 基因后消失。在 msh6Δ 菌株中，剩余的、仍然很强的诱变表型协同升高，并且具有 Pol δ 错误造成的突变谱特征。结果支持这样一种模型，即由于缺乏 Pol ϵ 的催化结构域而导致的移动缓慢的复制叉导致 Pol ζ 参与更多的诱变 DNA 合成，以及在复制过程中 Pol δ 的校对减少。
