RUI: The Synthesis and Degradation of a Unique Bacterial Polymer

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9728609 Allen The objective of the research is to study the synthesis and degradation of the only known nonprotein polymer whose function is the storage of nitrogen, using a multidisciplinary approach involving three faculty members and undergraduate women students in chemistry, biological chemistry and biological sciences. The metabolism of cyanophycin (multi-L-arginyl poly L-aspartic acid ) will be investigated by enzyme analysis and purification and by in vivo and in vitro NMR spectroscopy after labeling cyanobacteria with 15 N-labeled nitrogen sources. Nitrogen metabolism will be studied during normal growth and during growth under various conditions of nutrient stress. Experiments will be designed to determine whether cyanophycin has a dynamic role in cyanobacterial metabolism. Cyanophycin is the only known nonprotein polymer whose function is the storage of nitrogen. Little is known about mechanisms of its synthesis and degradation although it accumulates in large amounts during nutrient stress and during nitrogen fixation. It is mobilized when cyanobacteria are starved for nitrogen. If cyanophycin is an obligatory intermediate in the flow of nitrogen into the metabolic pool, its role in cyanobacterial metabolism will be central. It is therefore important to understand regulatory strategies and how storage is integrated with intermediary metabolism. These studies will also help define how macronutrient limitation and stress alter metabolic fluxes in cells. The strategy of accumulating nitrogen when it is available and using it later must impart an important selective advantage to the organism employing that strategy. Studies of the mechanisms involved in specific environmental responses will provide new information about gene regulation and pathways leading from the sensing of environmental signals to the regulation of enzymatic activities.