Understanding the nanoscale dynamics of critical plant membrane proteins involved in photosynthesis using cutting-edge microscopy techniques

Structural biology is often conducted using “static” snapshots of dynamic systems, therefore information on assembly/disassembly processes are poorly resolved. New quantitative approaches, often developed in collaboration with physicists and chemists, can provide dynamic mechanistic information. Timeresolved Electron Microscopy (TrEM), video-speed Atomic Force Microscopy (AFM) and Fluorescence Lifetime Imaging Microscopy (FLIM) are being developed to provide temporally-resolved structural biology. This project integrates newly developed methodologies in TrEM and AFM/FLIM to address fundamental questions in the biophysics of photosynthesis, relevant for the next generation of solar technologies.

Photosystem II (PSII) is a membrane protein supercomplex, essential for photosynthesis in plants and algae. PSII contains “core” subunits and many loosely associated “light harvesting” subunits, acting like an adjustable satellite dish. Time-resolved observation of structural changes to supercomplexes will provide new understanding of the dynamics of this important system. Furthermore, the PSII supercomplex is an excellent experimental model for method development because its biochemical purification is well-established and the protein is naturally fluorescent (“tags” are not needed). Objectives are: (1) Further develop the current TrEM apparatus into workflows with videospeed AFM/FLIM, (2) Quantify the kinetics of assembly/disassembly of PSII supercomplexes, and (3) Integrate spatiotemporal information to produce a mechanism for PSII assembly.