Thermococcus kodakarensis possesses two DNA polymerases, Pol B and Pol D. We generated a T. kodakarensis strain (DPB1) in which polB was completely deleted and a derivative of DPB1 in which polB was overexpressed; neither of the generated strains exhibited any growth delay, indicating that the lack or overexpression of Pol B in T. kodakarensis did not affect cell growth. We also found that DPB1 showed higher sensitivity to four DNA-damaging agents (ultraviolet C irradiation, γ-ray irradiation, methyl methanesulfonate, and mitomycin C) than the parental strain. The sensitivity of DPB1 was restored to the level of the parent strain by the introduction of a plasmid harboring polB, suggesting that the DNA damage-sensitive phenotype of DPB1 was due to the loss of polB. Collectively, these results indicate that Pol B is involved in DNA repair, but not DNA replication, which, in turn, implies that Pol D is the sole replicative DNA polymerase in Thermococcus species.

中文翻译：

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Pol B，一种家族 B DNA 聚合酶，在Thermococcus kodakarensis中对 DNA 修复很重要，但对 DNA 复制不重要

Thermococcus kodakarensis 拥有两种 DNA 聚合酶，Pol B 和 Pol D。我们生成了 polB 完全缺失的 T. kodakarensis 菌株 (DPB1) 和 polB 过表达的 DPB1 衍生物；产生的菌株都没有表现出任何生长延迟，表明 T. kodakarensis 中 Pol B 的缺乏或过度表达不会影响细胞生长。我们还发现 DPB1 对四种 DNA 损伤剂（紫外线 C 辐射、γ 射线辐射、甲基磺酸甲酯和丝裂霉素 C）比亲本菌株表现出更高的敏感性。通过引入含有 polB 的质粒，DPB1 的敏感性恢复到亲本菌株的水平，表明 DPB1 的 DNA 损伤敏感表型是由于 polB 的丢失。总的来说，这些结果表明 Pol B 参与了 DNA 修复，