Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea.
Division of Biomedical Convergence, College of Biomedical Science, Kangwon National University, Chuncheon, 24341, Republic of Korea; Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, 24341, Republic of Korea.
Biochem Biophys Res Commun. 2021 Sep 3;568:136-142. doi: 10.1016/j.bbrc.2021.06.076. Epub 2021 Jun 30.
Vibrio species are prevalent in the aquatic environments and can infect humans and aquatic organisms. Vibrio parahaemolyticus counteracts β-lactam antibiotics and enhances virulence using a regulation mechanism mediated by a two-component regulatory system (TCS) consisting of the VbrK histidine kinase and the VbrR response regulator. The periplasmic sensor domain of VbrK (VbrK) detects β-lactam antibiotics or undergoes S-nitrosylation in response to host nitrites. Although V. parahaemolyticus VbrK (vpVbrK) has recently been characterized through structural studies, it is unclear whether its structural features that are indispensable for biological functions are conserved in other VbrK orthologs. To structurally define the functionally critical regions of VbrK and address the structural dynamics of VbrK, we determined the crystal structures of Vibrio rotiferianus VbrK (vrVbrK) in two crystal forms and performed a comparative analysis of diverse VbrK structures. vrVbrK folds into a curved rod-shaped two-domain structure as observed in vpVbrK. The membrane-distal end of the vrVbrK structure, including the α3 helix and its neighboring loops, harbors both S-nitrosylation and antibiotic-sensing sites and displays high structural flexibility and diversity. Noticeably, the distal end is partially stabilized by a disulfide bond, which is formed by the cysteine residue that is S-nitrosylated in response to nitrite. Therefore, the distal end of VbrK plays a key role in initiating the VbrK-VbrR TCS pathway activation, and it is involved in the nitrosylation-mediated regulation of the structural dynamics of VbrK.
弧菌属物种在水生环境中很普遍，可感染人类和水生生物。副溶血性弧菌对抗β-内酰胺类抗生素，并通过由两个组件调节系统（TCS）组成的调节机制增强毒力，该调节系统由 VbrK 组氨酸激酶和 VbrR 反应调节剂组成。VbrK（VbrK）的周质感应结构域检测β-内酰胺类抗生素或在响应宿主亚硝酸盐时发生 S-亚硝基化。尽管副溶血性弧菌 VbrK（vpVbrK）已通过结构研究进行了表征，但尚不清楚其对于生物学功能必不可少的结构特征是否在其他 VbrK 直系同源物中保守。为了从结构上定义 VbrK 的功能关键区域，并解决 VbrK 的结构动力学问题，我们确定了两种晶型的旋转弧菌 VbrK（vrVbrK）的晶体结构，并对不同的 VbrK 结构进行了比较分析。vrVbrK 折叠成类似于 vpVbrK 的弯曲杆状两结构域结构。vrVbrK 结构的膜远末端，包括α3 螺旋及其相邻环，同时具有 S-亚硝基化和抗生素感应位点，并且显示出较高的结构灵活性和多样性。值得注意的是，末端的一部分通过二硫键稳定，该二硫键是由响应亚硝酸盐而被 S-亚硝基化的半胱氨酸残基形成的。因此，VbrK 的远末端在启动 VbrK-VbrR TCS 途径的激活中起关键作用，并且参与 VbrK 结构动力学的亚硝基化介导的调节。
