A Unique B-Family DNA Polymerase Facilitating Error-Prone DNA Damage Tolerance in Crenarchaeota
A Unique B-Family DNA Polymerase Facilitating Error-Prone DNA Damage Tolerance in Crenarchaeota
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DOI：
10.3389/fmicb.2020.01585
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发表时间：
2020-07-23
影响因子：
5.2
通讯作者：
She, Qunxin
中科院分区：
文献类型：
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作者：
Feng, Xu;Liu, Xiaotong;She, Qunxin
岛紫叶虫编码四种DNA聚合酶：三种属于b家族（Dpo1、Dpo2和Dpo3），一种属于y家族（Dpo4）。Western分析显示，在四种聚合酶中，只有Dpo2表现出DNA损伤诱导的表达。研究这些DNA聚合酶如何促进DNA损伤耐受性。对Islandicus的编码基因进行了遗传分析。质粒携带的基因表达表明，Dpo2以突变为代价增加DNA损伤后的细胞存活。基因缺失研究表明，虽然po1是必不可少的，但其余三个基因是可有可无的。此外，虽然Dpo4在内务翻译DNA合成（TLS）中起作用，但Dpo2作为一种b家族DNA聚合酶，曾被预测为失活，作为一种损伤诱导的TLS酶，只负责靶向诱变，促进GC到AT/TA的转化过程。总之，我们的数据表明，Dpo2是负责DNA损伤耐受性的主要DNA聚合酶，是靶向诱变的主要来源。考虑到编码Dpo2的古细菌也具有低gc组成的基因组，Dpo2依赖性DNA修复途径可能在该古细菌谱系中保守。
Sulfolobus islandicuscodes for four DNA polymerases: three are of the B-family (Dpo1, Dpo2, and Dpo3), and one is of the Y-family (Dpo4). Western analysis revealed that among the four polymerases, only Dpo2 exhibited DNA damage-inducible expression. To investigate how these DNA polymerases could contribute to DNA damage tolerance inS. islandicus, we conducted genetic analysis of their encoding genes in this archaeon. Plasmid-borne gene expression revealed that Dpo2 increases cell survival upon DNA damage at the expense of mutagenesis. Gene deletion studies showed althoughdpo1is essential, the remaining three genes are dispensable. Furthermore, although Dpo4 functions in housekeeping translesion DNA synthesis (TLS), Dpo2, a B-family DNA polymerase once predicted to be inactive, functions as a damage-inducible TLS enzyme solely responsible for targeted mutagenesis, facilitating GC to AT/TA conversions in the process. Together, our data indicate that Dpo2 is the main DNA polymerase responsible for DNA damage tolerance and is the primary source of targeted mutagenesis. Given that crenarchaea encoding a Dpo2 also have a low-GC composition genome, the Dpo2-dependent DNA repair pathway may be conserved in this archaeal lineage.