Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9749 AG Groningen, the Netherlands.
Mol Microbiol. 2011 Nov;82(4):807-17. doi: 10.1111/j.1365-2958.2011.07861.x. Epub 2011 Oct 18.
Archaea, like bacteria and eukaryotes, contain proteins involved in various mechanisms of DNA repair, highlighting the importance of these processes for all forms of life. Species of the order Sulfolobales of hyperthermophilic crenarchaeota are equipped with a strongly UV-inducible type IV pilus system that promotes cellular aggregation. Here we demonstrate by fluorescence in situ hybridization that cellular aggregates are formed based on a species-specific recognition process and that UV-induced cellular aggregation mediates chromosomal marker exchange with high frequency. Recombination rates exceeded those of uninduced cultures by up to three orders of magnitude. Knockout strains of Sulfolobus acidocaldarius incapable of pilus production could not self-aggregate, but were partners in mating experiments with wild-type strains indicating that one cellular partner can mediate the DNA transfer. Since pilus knockout strains showed decreased survival upon UV treatment, we conclude that the UV-inducible DNA transfer process and subsequent homologous recombination represents an important mechanism to maintain chromosome integrity in Sulfolobus. It might also contribute substantially to the frequent chromosomal DNA exchange and horizontal gene transfer in these archaea in their natural habitat.
古菌与细菌和真核生物一样，含有参与各种 DNA 修复机制的蛋白质，这突出了这些过程对所有生命形式的重要性。嗜热泉古菌的 Sulfolobales 目物种具有强烈的 UV 诱导型 IV 型菌毛系统，可促进细胞聚集。在这里，我们通过荧光原位杂交证明，细胞聚集是基于种特异性识别过程形成的，并且 UV 诱导的细胞聚集以高频率介导染色体标记交换。重组率比未诱导的培养物高出多达三个数量级。无法产生菌毛的 Sulfolobus acidocaldarius 缺失菌株不能自我聚集，但可以与野生型菌株进行交配实验，这表明一个细胞伴侣可以介导 DNA 转移。由于菌毛缺失菌株在 UV 处理后存活率下降，我们得出结论，UV 诱导的 DNA 转移过程和随后的同源重组代表了维持 Sulfolobus 染色体完整性的重要机制。它也可能在这些古菌的自然栖息地中对频繁的染色体 DNA 交换和水平基因转移做出重大贡献。
