Silver Ions Caused Faster Diffusive Dynamics of Histone-Like Nucleoid-Structuring Proteins in Live Bacteria
Silver Ions Caused Faster Diffusive Dynamics of Histone-Like Nucleoid-Structuring Proteins in Live Bacteria
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DOI：
10.1128/aem.02479-19
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发表时间：
2020-03-01
影响因子：
4.4
通讯作者：
Wang, Yong
中科院分区：
文献类型：
--
作者：
Sadoon, Asmaa A.;Khadka, Prabhat;Wang, Yong
近年来，银离子（Ag+）的抗菌活性和作用机制受到广泛关注。然而，该领域的动态研究很少见。在这里，我们报告了使用单粒子跟踪光激活定位显微镜（sptPALM）测量Ag（+）离子对活细菌中组蛋白样核结构（H-NS）蛋白动力学的影响。研究发现，用 Ag(+) 离子处理细菌会导致 H-NS 蛋白的扩散动力学更快。使用多种技术来理解观察到的更快动力学的机制。对纯化的 H-NS 蛋白进行电泳迁移率变动分析表明，Ag+ 离子削弱了 H-NS 蛋白与 DNA 之间的结合。等温滴定量热法证实 DNA 和 Ag+ 离子直接相互作用。我们最近开发的基于弯曲 DNA 的传感方法表明 Ag+ 离子导致双链 DNA 去杂交（即解离成单链）。这些证据使我们得出了一个合理的机制，可以观察到活细菌中 H-NS 蛋白在 Ag+ 离子作用下的动力学更快：Ag+ 诱导的 DNA 去杂交削弱了 H-NS 蛋白和 DNA 之间的结合。这项工作强调了活细胞中单个蛋白质的动态研究对于了解细菌中抗菌剂的功能的重要性。重要性近年来，对常用抗生素产生耐药性的所谓“超级细菌”已成为对公众健康的全球性威胁，各种形式的贵金属（例如银）因其抗菌活性而受到广泛关注。然而，现有文献中的研究大多依赖于传统的生物测定法来研究银的抗菌机制；此外，对于理解银对细菌内部分子动力学的影响，时间分辨率在很大程度上是缺失的。在这里，我们报告了我们使用单粒子跟踪光激活定位显微镜研究纳米级银离子对活细菌中组蛋白样核结构（H-NS）蛋白扩散动力学的抗菌作用。这项工作强调了活细胞中单一蛋白质的动态研究对于了解细菌中抗菌剂的功能的重要性。
The antimicrobial activity and mechanism of silver ions (Ag+) have gained broad attention in recent years. However, dynamic studies are rare in this field. Here, we report our measurement of the effects of Ag(+ )ions on the dynamics of histone-like nucleoid-structuring (H-NS) proteins in live bacteria using single-particle-tracking photoactivated localization microscopy (sptPALM). It was found that treating the bacteria with Ag(+ )ions led to faster diffusive dynamics of H-NS proteins. Several techniques were used to understand the mechanism of the observed faster dynamics. Electrophoretic mobility shift assay on purified H-NS proteins indicated that Ag+ ions weaken the binding between H-NS proteins and DNA. Isothermal titration calorimetry confirmed that DNA and Ag+ ions interact directly. Our recently developed sensing method based on bent DNA suggested that Ag+ ions caused dehybridization of double-stranded DNA (i.e., dissociation into single strands). These evidences led us to a plausible mechanism for the observed faster dynamics of H-NS proteins in live bacteria when subjected to Ag+ ions: Ag+-induced DNA dehybridization weakens the binding between H-NS proteins and DNA. This work highlighted the importance of dynamic study of single proteins in live cells for understanding the functions of antimicrobial agents in bacteria.IMPORTANCE As so-called "superbug" bacteria resistant to commonly prescribed antibiotics have become a global threat to public health in recent years, noble metals, such as silver, in various forms have been attracting broad attention due to their antimicrobial activities. However, most of the studies in the existing literature have relied on the traditional bioassays for studying the antimicrobial mechanism of silver; in addition, temporal resolution is largely missing for understanding the effects of silver on the molecular dynamics inside bacteria. Here, we report our study of the antimicrobial effect of silver ions at the nanoscale on the diffusive dynamics of histone-like nucleoid-structuring (H-NS) proteins in live bacteria using single-particle-tracking photoactivated localization microscopy. This work highlights the importance of dynamic study of single proteins in live cells for understanding the functions of antimicrobial agents in bacteria.