Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany.
Biophys J. 2023 Feb 21;122(4):624-631. doi: 10.1016/j.bpj.2023.01.018. Epub 2023 Jan 19.
In biology, release of Ca ions in the cytosol is essential to trigger or control many cell functions. Calcium signaling acutely depends on lipid membrane permeability to Ca. For proper understanding of membrane permeability to Ca, both membrane hydration and the structure of the hydrophobic core must be taken into account. Here, we vary the hydrophobic core of bilayer membranes and observe different types of behavior in high-throughput wide-field second harmonic imaging. Ca translocation is observed through mono-unsaturated (DOPC:DOPA) membranes, reduced upon the addition of cholesterol, and completely inhibited for branched (DPhPC:DPhPA) and poly-unsaturated (SLPC:SLPA) lipid membranes. We propose, using molecular dynamics simulations, that ion transport occurs through ion-induced transient pores, which requires nonequilibrium membrane restructuring. This results in different rates at different locations and suggests that the hydrophobic structure of lipids plays a much more sophisticated regulating role than previously thought.
在生物学中，细胞质中钙离子的释放对于触发或控制许多细胞功能至关重要。钙信号的急性依赖于脂质膜对 Ca 的通透性。为了正确理解 Ca 通过膜的通透性，必须考虑膜的水合作用和疏水区的结构。在这里，我们改变双层膜的疏水区，并在高通量宽场二次谐波成像中观察到不同类型的行为。通过单不饱和（DOPC:DOPA）膜观察到 Ca 转运，加入胆固醇后减少，而支化（DPhPC:DPhPA）和多不饱和（SLPC:SLPA）脂质膜则完全抑制。我们使用分子动力学模拟提出，离子通过离子诱导的瞬时孔进行运输，这需要非平衡的膜重构。这导致不同位置的不同速率，并表明脂质的疏水结构起着比以前认为的更为复杂的调节作用。
