Organization and Dynamics in Photosynthetic Reaction Centers and Model Membrane Architectures

Stanford University, Stanford CA

Investigators

Abstract

Photosynthetic reaction center (RC) is a remarkable machine that absorbs light and transfers electrons across a biological membrane. Membranes are very thin insulators, so this process is like charging a capacitor. Once charged, the capacitor discharges by driving the biosynthesis of stable energetic molecules or fuels. All life on earth depends on this process. This research will lead to a better understanding of the mechanisms by which photosynthetic reaction centers harvest and store solar energy, and the development of model membrane assemblies that mimic natural biological membranes and their interactions. This project will modulate the properties of key amino acids near to the reactive chromophores in the RC to systematically understand why electrons take the pathway they do and by what precise mechanism. A significant part of this work involves the development of new experimental and theoretical methods that will have a broad impact in other areas of science and technology. This research program will continue to support the development of a generation of young scientists with diverse backgrounds, primarily graduate students, who go on to productive careers at the interface of the physical sciences and biology, biotechnology, and energy-related science. This project focuses on two related topics; the mechanism of charge separation in bacterial photosynthetic reaction centers, and the development of novel methods to assemble and image model membrane architectures. This project will implement site specific modification of functionally important amino acids with non-canonical amino acids and the introduction of nitrile spectator probes for electron transfer and membrane potential. This project will continue development of a "membrane interferometer", designed for simultaneous optical and electrical measurements on single integral membrane proteins such as ion channels, and develop novel methods to measure lipid diffusion on sub-micron sized membranes to explore the effects of curvature on diffusion. This project is supported by the Molecular Biophysics Cluster of the Molecular and Cellular Biosciences Division in the Biological Sciences Directorate. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.