(6fq) Characterizing the Structure and Function of a Protein Fusion Complex of Photosystem I and Hydrogenase Enzyme

Proteins are large, complex molecules, and their interactions within even the simplest of microorganisms are a complex and intriguing process, requiring a mechanistic understanding at the single molecule level that often defies the capabilities of current science and technology. Gaining insight into proteins and their interactions is crucial to our understanding of the biological world, and could provide technological advancement in alternative energy, drug discovery, and a wealth of other areas. Membrane proteins in particular comprise ~30% of open reading frames, yet represent only a small fraction of known protein structures due to a lack of understanding of the effects of protein-environment interactions on their structure and stability. Here, we are interested in the study of structural effects on the stability and activity of redox proteins. In particular, we are focused on generating protein fusions between the integral membrane protein photosystem I (PSI) of Synechocystis sp. PCC 6803 and the membrane-bound hydrogenase (MBH) of Ralstonia eutropha H16, a unique in vitro complex capable of harnessing solar energy for the production of molecular hydrogen (H₂). We present our study of the detergent-solubilized solution structure of PSI using small-angle neutron scattering (SANS) experiments and all-atom molecular dynamics (AAMD) simulations, and discuss our results in applying a similar approach to studying PSI-MBH protein fusions. By utilizing a combination of computational modeling and experimental characterization of these fusion complexes, we hope to provide a novel method for probing the structure-function relationship that governs redox proteins.