Functional Biogenesis of V-ATPase in the Vacuolar System of Plants and Fungi

The vacuolar H+-ATPase (V-ATPase) is one of the most fundamental enzymes in nature. It pumps protons into the vacuolar system of eukaryotic cells and provides the energy for numerous transport systems. Through our BARD grant we discovered a novel family of membrane chaperones that modulate the amount of membrane proteins. We also elucidated the mechanism by which assembly factors guide the membrane sector of V-ATPase from the endoplasmic reticulum to the Golgi apparatus. The major goal of the research was to understand the mechanism of action and biogenesis of V-ATPase in higher plants and fungi. The fundamental question of the extent of acidification in organelles of the vacuolar system was addressed by studying the V-ATPase of lemon fruit, constructing lemon cDNAs libraries and study their expression in mutant yeast cells. The biogenesis of the enzyme and its function in the Golgi apparatus was studied in yeast utilizing a gallery of secretory mutants available in our laboratories. One of the goals of this project is to determine biochemically and genetically how V-ATPase is assembled into the different membranes of a wide variety of organelles and what is the mechanism of its action.The results of this project advanced out knowledge along these lines.