论文标题
由表面pH梯度驱动的膜变形模型
A model of membrane deformations driven by a surface pH gradient
论文作者
论文摘要
许多细胞细胞器是膜结合的结构，具有复杂的膜组成和形状。已经观察到它们的形状取决于细胞器的代谢状态，并且仍然积极研究了生化途径和膜形状的机制。在这里，我们研究了通过广义的Helfrich自由能在脂质组成和膜几何形状中的模型耦合不均匀性。我们得出所得的应力张量，即管状膜的绿色功能，并计算诱导变形的相图。然后，我们应用该模型来研究描述为支持其表面pH梯度的膜管的线粒体Cristae的变形。该梯度反过来控制了膜的脂质组成，通过质子化/去质子化的质子化，这是基于酸的脂质，已知对线粒体形状和功能至关重要。我们的模型预测了在提交给质子梯度时观察到的Cristea形状变化的管变形的外观。
Many cellular organelles are membrane-bound structures with complex membrane composition and shape. Their shapes have been observed to depend on the metabolic state of the organelle, and the mechanisms that couple biochemical pathways and membrane shape are still actively investigated. Here, we study a model coupling inhomogeneities in the lipid composition and membrane geometry via a generalized Helfrich free energy. We derive the resulting stress tensor, the Green's function for a tubular membrane and compute the phase diagram of the induced deformations. We then apply this model to study the deformation of mitochondria cristae described as membrane tubes supporting a pH gradient at its surface. This gradient in turn controls the lipid composition of the membrane via the protonation/deprotonation of cardiolipins, which are acid-based lipids known to be crucial for mitochondria shape and functioning. Our model predicts the appearance of tube deformations resembling the observed shape changes of cristea when submitted to a proton gradient.
