霍乱弧菌是革兰氏阴性,兼性厌氧细菌物种,导致严重的疾病,可以在各种碳源上生长,包括几丁质多糖。在盐水中,它附着在几丁质表面不仅是营养募集的第一步,也是霍乱流行的重要机制。在这项研究中,我们报道了一种壳寡糖特异性的壳聚糖蛋白的首次表征,VcChiP,来自霍乱弧菌型菌株O1的细胞包膜。我们模拟了VcChiP的结构,揭示了在磷脂双层中形成单通道的三聚体圆柱体。膜重构的VcChiP通道是高度动态的和电压诱导的。子状态洞口O1\',O2\',和O3',在完全开放状态O1,O2和O3之间,是极性选择性的,具有非欧姆电导曲线。脂质体溶胀试验的结果表明,VcChiP可以转运单糖,以及壳寡糖,但不是其他低聚糖。值得注意的是,表达异源VcChiP的大肠杆菌的外膜孔蛋白(omp)缺陷菌株可以在补充有小壳寡糖的M9基本培养基上生长。这些结果支持几丁质营养素在细菌对几丁质营养素的适应性存活中的关键作用。我们的发现还提出了一种有希望的基于表面暴露的外膜蛋白的疫苗开发方法,以及基于壳寡糖模拟类似物的新型抗霍乱药的设计。
Vibrio cholerae is a Gram-negative, facultative anaerobic bacterial species that causes serious disease and can grow on various carbon sources, including chitin polysaccharides. In saltwater, its attachment to chitin surfaces not only serves as the initial step of nutrient recruitment but is also a crucial mechanism underlying cholera epidemics. In this study, we report the first characterization of a chitooligosaccharide-specific chitoporin, VcChiP, from the cell envelope of the V. cholerae type strain O1. We modeled the structure of VcChiP, revealing a trimeric cylinder that forms single channels in phospholipid bilayers. The membrane-reconstituted VcChiP channel was highly dynamic and voltage induced. Substate openings O1\', O2\', and O3\', between the fully open states O1, O2, and O3, were polarity selective, with nonohmic conductance profiles. Results of liposome-swelling assays suggested that VcChiP can transport monosaccharides, as well as chitooligosaccharides, but not other oligosaccharides. Of note, an outer-membrane porin (omp)-deficient strain of Escherichia coli expressing heterologous VcChiP could grow on M9 minimal medium supplemented with small chitooligosaccharides. These results support a crucial role of chitoporin in the adaptive survival of bacteria on chitinous nutrients. Our findings also suggest a promising means of vaccine development based on surface-exposed outer-membrane proteins and the design of novel anticholera agents based on chitooligosaccharide-mimicking analogs.