GRAIL · Time-resolved imaging of membrane transporter dynamics under physiological ionic gradients

Without biological membranes, there would be no life as we know it. Lipid bilayers shield cellular content from the environment, creating defined micro environments with specific functionality. Transport of molecules and information across these membranes is carried out by integral membrane protein channels, receptors, pumps and transporters. Living cells maintain chemical gradients and electrical potential differences across their membranes, the potential energy of which can be accessed by the membrane proteins to perform useful work. Indeed, central processes such as metabolic energy generation and nerve impulse propagation directly depend on these membrane gradients. Due to their core role in the life of cells and in the health of living organisms, such proteins represent the majority of all current drug targets. Therefore, membrane proteins have been the focus of intense efforts to obtain high-resolution macromolecular structure information. However, the current lack of experimental methods to carry out time-resolved structural studies of membrane proteins at physiological temperatures and under physiological gradients leaves a gigantic blind spot is our mechanistic understanding.We will address this challenge by bringing together our complementary expertise in membrane protein biology, time-resolved structural studies, photochemistry and nano fabrication methods. We will link a set of state-of-the-art technologies to build a technology platform, based on a partitioned microfluidic liquid sample environment, optimised for high-resolution, time-resolved, structural studies of membrane proteins by serial electron diffraction from 2D crystals at room temperature and in the presence of physiologically meaningful membrane gradients for the first time. This will allow us to structurally validate models based on biochemical and computational data, and uncover new possibilities for modulation of function by small molecule therapeutics based on allosteric regulation.