van Wolferen Marleen, Wagner Alexander, van der Does Chris, Albers Sonja-Verena
Molecular Biology of Archaea, Institute of Biology II - Microbiology, University of Freiburg, 79104 Freiburg, Germany.
Molecular Biology of Archaea, Institute of Biology II - Microbiology, University of Freiburg, 79104 Freiburg, Germany
Proc Natl Acad Sci U S A. 2016 Mar 1;113(9):2496-501. doi: 10.1073/pnas.1513740113. Epub 2016 Feb 16.
The intercellular transfer of DNA is a phenomenon that occurs in all domains of life and is a major driving force of evolution. Upon UV-light treatment, cells of the crenarchaeal genus Sulfolobus express Ups pili, which initiate cell aggregate formation. Within these aggregates, chromosomal DNA, which is used for the repair of DNA double-strand breaks, is exchanged. Because so far no clear homologs of bacterial DNA transporters have been identified among the genomes of Archaea, the mechanisms of archaeal DNA transport have remained a puzzling and underinvestigated topic. Here we identify saci_0568 and saci_0748, two genes from Sulfolobus acidocaldarius that are highly induced upon UV treatment, encoding a transmembrane protein and a membrane-bound VirB4/HerA homolog, respectively. DNA transfer assays showed that both proteins are essential for DNA transfer between Sulfolobus cells and act downstream of the Ups pili system. Our results moreover revealed that the system is involved in the import of DNA rather than the export. We therefore propose that both Saci_0568 and Saci_0748 are part of a previously unidentified DNA importer. Given the fact that we found this transporter system to be widely spread among the Crenarchaeota, we propose to name it the Crenarchaeal system for exchange of DNA (Ced). In this study we have for the first time to our knowledge described an archaeal DNA transporter.
DNA的细胞间转移是一种在所有生命域中都存在的现象，并且是进化的主要驱动力。经紫外线处理后，硫化叶菌属的嗜热栖热放线菌细胞会表达Ups菌毛，从而启动细胞聚集体的形成。在这些聚集体中，用于修复DNA双链断裂的染色体DNA会发生交换。由于迄今为止在古菌基因组中尚未发现细菌DNA转运蛋白的明确同源物，古菌DNA转运机制仍然是一个令人困惑且研究不足的课题。在这里，我们鉴定出嗜热栖热放线菌中的两个基因saci_0568和saci_0748，它们在紫外线处理后会被高度诱导，分别编码一种跨膜蛋白和一种膜结合的VirB4/HerA同源物。DNA转移试验表明，这两种蛋白质对于嗜热栖热放线菌细胞间的DNA转移至关重要，并且在Ups菌毛系统的下游发挥作用。我们的结果还表明，该系统参与DNA的导入而非导出。因此，我们提出Saci_0568和Saci_0748都是一个先前未被鉴定的DNA导入蛋白的组成部分。鉴于我们发现这个转运系统在泉古菌门中广泛分布，我们提议将其命名为泉古菌DNA交换系统（Ced）。据我们所知，在这项研究中我们首次描述了一种古菌DNA转运蛋白。
