Centro de Biología Molecular Severo Ochoa (CBMSO), Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, 28049, Spain.
Department of Biotechnology, Faculty of Experimental Sciences, Universidad Francisco de Vitoria, Madrid, 28223, Spain.
Environ Microbiol. 2020 Nov;22(11):4647-4657. doi: 10.1111/1462-2920.15207. Epub 2020 Sep 3.
Primase-polymerases (Ppol) are one of the few enzymes able to start DNA synthesis on ssDNA templates. The role of Thermus thermophilus HB27 Ppol, encoded along a putative helicase (Hel) within a mobile genetic element (ICETh2), has been studied. A mutant lacking Ppol showed no effects on the replication of the element. Also, no apparent differences in the sensitivity to DNA damaging agents and other stressors or morphological changes in the mutant cells were detected. However, the mutants lacking Ppol showed an increase in two to three orders of magnitude in their transformation efficiency with plasmids and genomic DNA acquired from the environment (eDNA), independently of its origin and G + C content. In contrast, no significant differences with the wild type were detected when the cells received the DNA from other T. thermophilus partners in conjugation-like mating experiments. The similarities of this behaviour with that shown by mutants lacking the Argonaute (ThAgo) protein suggests a putative partnership Ppol-ThAgo in the DNA-DNA interference mechanism of defence, although other eDNA defence mechanisms independent of ThAgo cannot be discarded.
引物酶-聚合酶（Ppol）是少数能够在单链 DNA 模板上启动 DNA 合成的酶之一。研究了编码在移动遗传元件（ICETh2）内的假定解旋酶（Hel）中的嗜热栖热菌 HB27 Ppol 的作用。缺乏 Ppol 的突变体对元件的复制没有影响。此外，在突变细胞中未检测到对 DNA 损伤剂和其他应激源的敏感性或形态变化的明显差异。然而，缺乏 Ppol 的突变体在转化效率上提高了两到三个数量级，与从环境中获得的质粒和基因组 DNA（eDNA）相关，与 eDNA 的来源和 G + C 含量无关。相比之下，在共轭样交配实验中，当细胞从其他嗜热栖热菌的 DNA 中接收 DNA 时，与野生型没有显著差异。这种行为与缺乏 Argonaute（ThAgo）蛋白的突变体所表现出的行为相似，表明在 DNA-DNA 干扰防御机制中存在 Ppol-ThAgo 的假定伙伴关系，尽管不能排除其他不依赖 ThAgo 的 eDNA 防御机制。
