MECHANISM OF THE ENERGY-STORING REACTIONS IN PHOTOSYNTHETIC ORGANISMS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The chemical reactions leading to long-term energy storage in photosynthetic systems take place within the membrane-bound reaction center complex and an associated group of proteins that make up an electron transport chain. One of the central goals of our research is to identify the molecular parameters responsible for the fact that essentially every photon absorbed by the system leads to stable products. To this end, we do a variety of kinetic, thermodynamic and structural measurements on antenna complexes, reaction centers, electron transport proteins and isolated pigments, using a number of techniques, including ultrafast laser flash photolysis and UV-VIS, fluorescence and electron spin resonance spectroscopies, as well as biochemical and molecular biological analysis. The appearance of photosynthesis and other metabolic processes such as nitrogen fixation had profound effects on the evolution of advanced life on Earth. Our analysis of whole bacterial genomes has revealed that these metabolic processes have complex evolutionary histories, including substantial horizontal gene transfer. We have also used a combination of genomic, molecular evolution techniques and biochemical analysis to identify and characterize previously unknown enzyme complexes with novel activities.