State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
Sci China Life Sci. 2016 Jul;59(7):709-16. doi: 10.1007/s11427-016-5076-8. Epub 2016 Jun 22.
Euryarchaeota and Crenarchaeota, the two main lineages of the domain Archaea, encode different chromatin proteins and differ in the use of replicative DNA polymerases. Crenarchaea possess a single family B DNA polymerase (PolB), which is capable of strand displacement modulated by the chromatin proteins Cren7 and Sul7d. Euryarchaea have two distinct replicative DNA polymerases, PolB and PolD, a family D DNA polymerase. Here we characterized the strand displacement activities of PolB and PolD from the hyperthermophilic euryarchaeon Pyrococcus furiosus and investigated the influence of HPfA1, a homolog of eukaryotic histones from P. furiosus, on these activities. We showed that both PolB and PolD were efficient in strand displacement. HPfA1 inhibited DNA strand displacement by both DNA polymerases but exhibited little effect on the displacement of a RNA strand annealed to single-stranded template DNA. This is consistent with the finding that HPfA1 bound more tightly to double-stranded DNA than to a RNA:DNA hybrid. Our results suggest that, although crenarchaea and euryarchaea differ in chromosomal packaging, they share similar mechanisms in modulating strand displacement by DNA polymerases during lagging strand DNA synthesis.
古菌域的两大主要分支广古菌门和泉古菌门编码不同的染色质蛋白，且在复制 DNA 聚合酶的使用上存在差异。泉古菌拥有单一的 B 家族 DNA 聚合酶（PolB），该酶能够被染色质蛋白 Cren7 和 Sul7d 调节的链置换所激活。广古菌则具有两种截然不同的复制 DNA 聚合酶，B 家族的 PolB 和 D 家族的 PolD。在此，我们对来自嗜热古菌 Pyrococcus furiosus 的 PolB 和 PolD 的链置换活性进行了表征，并研究了与真核生物组蛋白具有同源性的 HPfA1 对这些活性的影响。我们表明，PolB 和 PolD 都能有效地进行链置换。HPfA1 能抑制两种 DNA 聚合酶的 DNA 链置换，但对与单链模板 DNA 退火的 RNA 链的置换几乎没有影响。这与 HPfA1 与双链 DNA 的结合比与 RNA:DNA 杂交体的结合更紧密的发现一致。我们的结果表明，尽管泉古菌和广古菌在染色体包装上存在差异，但它们在滞后链 DNA 合成过程中通过 DNA 聚合酶调节链置换的机制相似。
