POWRE: The Calvin Cycle: Evolution and Catalytic Function of Phosphoribulo Kinase in a Marine Chromophyte

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CattolicoThe Calvin cycle, the biological process by which carbon in atmospheric CO2 is converted into carbohydrate, has functioned in photo-oxygenic cells for over 3.5 billion years. Phosphoribulokinase (PRK) acts as a throttle that governs the progression of this biochemical pathway. The goal of this project is to probe the evolutionary origin and catalytic function of PRK in the chromophytic alga Heterosigma carterae. Chromophytic plants contribute extensively to global CO2 cycling, and currently there is no biochemical information on PRK in this group of organisms. The formation of toxic and noxious algal blooms world-wide by Heterosigma carterae, a golden-brown alga, is another reason that understanding the biology of this organism is so important to mankind.During the term of this award the investigator's laboratory will finish sequencing the gene for Heterosigma PRK. Through homology modeling the investigator will identify residues likely to be crucial for enzymatic function; in the future these amino acids will be mutagenized to determine their effects on function. In addition, the enzyme will be characterized. The Heterosigma PRK gene will be over-expressed in yeast to produce large quantities of the enzyme. An assay for PRK activity will be developed and used in measuring the effects of temperature, pH, inhibitors, and substrates. These studies, when complete, will form a reference database for PRK function in chromophytic plants. This is a POWRE project. During the sabbatical supported by this award, the investigator will have the opportunity to learn new techniques and to become more familiar with the culture and needs of scientific companies. The new knowledge will enhance the investigator's own research and her value as a mentor and as a contributor to the university community.