Miyabayashi Hiroka, Jain Rupal, Suzuki Shoji, Grogan Dennis W, Kurosawa Norio
Department of Environmental Engineering for Symbiosis, Graduate School of Science and Engineering, Soka University, Tokyo, Japan.
Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States.
Front Microbiol. 2020 Dec 23;11:613375. doi: 10.3389/fmicb.2020.613375. eCollection 2020.
The thermophilic crenarchaeon has four DNA polymerases (DNAPs): PolB1, PolB2, PolB3, and Dbh (PolY). Previous studies suggested that PolB1 is the main replicative DNAP of whereas PolB2 and Y-family polymerases Dpo4 () or Dbh are involved in DNA repair and translesion DNA synthesis. On the other hand, there are various opinions about the role of PolB3, which remains to be clearly resolved. In order to examine the roles of the DNAPs of through experiments, we constructed , , and deletion strains and characterized their phenotypes. Efforts to construct a deletion strain were not successful; in contrast, it was possible to isolate triple gene-deletion strains lacking , , and . The growth of these strains was nearly the same as that of the parent strains under normal growth conditions. The , , and single-deletion strains were sensitive to some types of DNA-damaging treatments, but exhibited normal sensitivity to UV irradiation and several other damaging treatments. Overall, the genotype which exhibited the greatest sensitivity to the DNA-damaging treatments we tested was the Δ Δ combination, providing the first evidence of overlapping function for these two DNAPs . The results of our study strongly suggest that PolB1 is responsible for the DNA replication of both the leading and lagging strands and is sufficient to complete the repair of most DNA damage under normal growth conditions in .
嗜热泉古菌有四种DNA聚合酶（DNAPs）：PolB1、PolB2、PolB3和Dbh（PolY）。先前的研究表明，PolB1是该古菌的主要复制性DNAP，而PolB2和Y家族聚合酶Dpo4（）或Dbh参与DNA修复和跨损伤DNA合成。另一方面，关于PolB3的作用存在各种观点，仍有待明确解决。为了通过实验研究该古菌DNAPs的作用，我们构建了、和缺失菌株，并对它们的表型进行了表征。构建缺失菌株的尝试未成功；相反，可以分离出缺失、和的三基因缺失菌株。在正常生长条件下，这些菌株的生长与亲本菌株几乎相同。、和单缺失菌株对某些类型的DNA损伤处理敏感，但对紫外线照射和其他几种损伤处理表现出正常的敏感性。总体而言，对我们测试的DNA损伤处理表现出最大敏感性的基因型是ΔΔ组合，这为这两种DNAPs的重叠功能提供了首个证据。我们的研究结果强烈表明，PolB1负责前导链和后随链的DNA复制，并且足以在该古菌正常生长条件下完成大多数DNA损伤的修复。
