Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel.
Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 8410510, Israel.
J Struct Biol. 2018 Nov;204(2):191-198. doi: 10.1016/j.jsb.2018.08.008. Epub 2018 Aug 12.
Protein-DNA interactions are highly dependent on salt concentration. To gain insight into how such interactions are maintained in the highly saline cytoplasm of halophilic archaea, we determined the 3-D structure of VNG0258H/RosR, the first haloarchaeal DNA-binding protein from the extreme halophilic archaeon Halobactrium salinarum. It is a dimeric winged-helix-turn-helix (wHTH) protein with unique features due to adaptation to the halophilic environment. As ions are major players in DNA binding processes, particularly in halophilic environments, we investigated the solution structure of the ionic envelope and located anions in the first shell around the protein in the crystal using anomalous scattering. Anions that were found to be tightly bound to residues in the positively charged DNA-binding site would probably be released upon DNA binding and will thus make significant contribution to the driving force of the binding process. Unexpectedly, ions were also found in a buried internal cavity connected to the external medium by a tunnel. Our structure lays a solid groundwork for future structural, computational and biochemical studies on complexes of the protein with cognate DNA sequences, with implications to protein-DNA interactions in hyper-saline environments.
蛋白质与 DNA 的相互作用高度依赖于盐浓度。为了深入了解嗜盐古菌高度盐细胞质中这种相互作用是如何维持的，我们测定了来自极端嗜盐古菌盐杆菌的首个嗜盐古菌 DNA 结合蛋白 VNG0258H/RosR 的三维结构。它是一种二聚体的翼型螺旋-转角-螺旋（wHTH）蛋白，由于适应嗜盐环境而具有独特的特征。由于离子是 DNA 结合过程中的主要参与者，特别是在嗜盐环境中，我们研究了离子包络物的溶液结构，并使用异常散射在晶体中确定了蛋白质周围第一壳层中的阴离子。在带正电荷的 DNA 结合位点与残基结合的阴离子可能在 DNA 结合时被释放，因此会对结合过程的驱动力做出重大贡献。出乎意料的是，我们还在一个内部埋藏的空腔中发现了离子，该空腔通过一个隧道与外部介质相连。我们的结构为将来对该蛋白与同源 DNA 序列的复合物进行结构、计算和生化研究奠定了坚实的基础，这对高盐环境中的蛋白质-DNA 相互作用具有重要意义。
