Flegler Vanessa J, Rasmussen Akiko, Hedrich Rainer, Rasmussen Tim, Böttcher Bettina
Julius-Maximilians-Universität Würzburg, Biocenter and Rudolf-Virchow-Center, Josef-Schneider-Str. 2, Gebäude D15, Würzburg, Germany.
Julius-Maximilians-Universität Würzburg, Department of Biochemistry II, Am Hubland, Würzburg, Germany.
Nat Commun. 2025 Aug 23;16(1):7881. doi: 10.1038/s41467-025-63253-0.
Osmotically varying environments are challenging for bacterial cells. Sudden drops in osmolytes cause an increased membrane tension and rupture the cells in the absence of protective mechanisms. One family of protective proteins are mechanosensitive channels of small conductance that open in response to membrane tension. Although these channels have a common architecture, they vary widely in the number of transmembrane helices, conductivity, and gating characteristics. Although there are various structures of channels in the open and closed state, the underlying common principles of the gating mechanism remain poorly understood. Here we show that YnaI opens by radial relocation of the transmembrane sensor paddles together with a shortening of the pore, which contrasts the prototypic smaller MscS. A chimera of both channels with the YnaI sensor paddles and the pore containing C-terminal part of MscS is functional and has the tension response of the paddle donor. Our research shows that elements with different structural opening mechanisms can be mixed and matched within one channel as long as they support the common area expansion on the periplasmic side.
渗透变化的环境对细菌细胞构成挑战。渗透压突然下降会导致膜张力增加，在缺乏保护机制的情况下使细胞破裂。一类保护蛋白是小电导机械敏感通道，它们会响应膜张力而打开。尽管这些通道具有共同的结构，但它们在跨膜螺旋数量、电导率和门控特性方面差异很大。虽然有处于开放和关闭状态的各种通道结构，但门控机制的潜在共同原理仍知之甚少。在这里我们表明，YnaI 通过跨膜传感桨叶的径向重新定位以及孔的缩短而打开，这与原型较小的 MscS 形成对比。这两种通道的嵌合体，具有 YnaI 传感桨叶和包含 MscS C 端部分的孔，是有功能的，并且具有桨叶供体的张力响应。我们的研究表明，只要支持周质侧的共同面积扩展，具有不同结构开放机制的元件就可以在一个通道内混合和匹配。
