Bile salts and alkaline pH reciprocally modulate the interaction between the periplasmic domains of Vibrio cholerae ToxR and ToxS.
Bile salts and alkaline pH reciprocally modulate the interaction between the periplasmic domains of Vibrio cholerae ToxR and ToxS.
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DOI：
10.1111/mmi.13699
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发表时间：
2017-07
影响因子：
3.6
通讯作者：
Kull FJ
中科院分区：
文献类型：
--
作者：
Midgett CR;Almagro-Moreno S;Pellegrini M;Taylor RK;Skorupski K;Kull FJ
ToxR是一种跨膜转录因子，是霍乱弧菌毒力基因表达和人类定植所必需的。ToxR需要其操纵子伙伴ToxS（一种质周积分膜蛋白）才能充分发挥活性。这两种蛋白被认为通过它们各自的质周结构域ToxRp和ToxSp相互作用。此外，ToxR被认为对各种环境因素有反应，如胆汁盐和碱性pH值，但这些因素如何影响ToxR尚不清楚。利用核磁共振和相互下拉分析，我们提出了第一个直接证据，证明ToxR和ToxS物理相互作用。此外，利用核磁共振和DSF，我们发现胆盐胆酸盐和鹅脱氧胆酸盐与纯化的ToxRp相互作用并使其不稳定。令人惊讶的是，胆盐破坏ToxRp的稳定性增强了ToxRp和ToxSp之间的相互作用。相反，碱性pH是导致ToxR蛋白水解的因素之一，它降低了ToxRp和ToxSp之间的相互作用。总之，这些数据表明了一种模型，即胆汁盐或其他洗涤剂使ToxR不稳定，增加其与ToxS的相互作用，以促进充分的ToxR活性。随后，当霍乱弧菌在静止期后期碱化其环境时，两种蛋白之间的相互作用减少，从而使ToxR蛋白水解继续进行。
ToxR is a transmembrane transcription factor that is essential for virulence gene expression and human colonization by Vibrio cholerae. ToxR requires its operon partner ToxS, a periplasmic integral membrane protein, for full activity. These two proteins are thought to interact through their respective periplasmic domains, ToxRp and ToxSp. In addition, ToxR is thought to be responsive to various environmental cues, such as bile salts and alkaline pH, but how these factors influence ToxR is not yet understood. Using NMR and reciprocal pull down assays, we present the first direct evidence that ToxR and ToxS physically interact. Furthermore, using NMR and DSF, we show that the bile salts cholate and chenodeoxycholate interact with purified ToxRp and destabilize it. Surprisingly, bile salt destabilization of ToxRp enhanced the interaction between ToxRp and ToxSp. In contrast, alkaline pH, which is one of the factors that leads to ToxR proteolysis, decreased the interaction between ToxRp and ToxSp. Taken together, these data suggest a model whereby bile salts or other detergents destabilize ToxR, increasing its interaction with ToxS to promote full ToxR activity. Subsequently, as V. cholerae alkalinizes its environment in late stationary phase, the interaction between the two proteins decreases allowing ToxR proteolysis to proceed.