Studying Dynamics and Energetics of Membrane Protein Oligomerization using Single Molecule Fluorescence

细胞壁或细胞膜由双层脂质膜和蛋白质组成，这些功能大分子控制电信号和底物进出细胞。膜蛋白也能感知外部刺激并触发内部的信号级联反应。直到最近，脂质膜本身主要被认为是一种被动基质，将细胞内部与外部分开。然而，近年来，人们越来越清楚地认识到脂膜的组成会影响蛋白质的功能。这也与我们的营养有关；已知胆固醇和欧米伽-3等化合物会进入脂质膜，改变其性质并调节蛋白质功能。相反，嵌入脂质膜的蛋白质也会改变其相行为和形态。

The cell wall, or cell membrane, is composed of a double-layered lipid film and proteins, functional macromolecules that control electrical signals and substrate transport in and out of the cell. Membrane proteins also sense external stimuli and trigger signaling cascades in the inside. Until recently, the lipid membrane itself was considered mainly a passive matrix that separates the cell interior from the exterior. However, recently, it became increasingly clear that the composition of the lipid membrane influences the functioning of the proteins. This also relates to our nutrition; compounds such as cholesterol and omega-3 are known to enter the lipid film, alter its properties and modulate protein function. Conversely, also the proteins embedded in the lipid membrane alter its phase behaviour and form. Many proteins oligomerize to larger complexes or clusters. We found recently that clustering of a membrane protein, the proton-gated KcsA channels, is related to deformations of the membrane. In this research program, we investigate the energetics of protein oligomerization and membrane deformations and their implication on protein function. We will directly observe the dynamics of protein oligomerization using single molecule fluorescence, where we can follow the movement of the proteins in an artificial membrane and determine the energy landscape of the clustering process. We will determine the effect of membrane curvature on protein function and oligomerization and characterize which classes of membrane proteins undergo lipid-mediated clustering.