GENE EXPRESSION AND CONTROL OF INTERMEDIATE METABOLISM

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Our goals are to understand the mechanism which operate to coordinate a set of genes. We have selected for study the genes which encode the enzymes of the glycolytic pathway. This pathway contains a number of well characterized metabolic steps whose principal end is the generation of energy from carbohydrates. In addition several intermediates have alternative metabolic fates most notably fatty acid biosynthesis. We are proposing to continue our characterization of the expression and structure of the genes which code for the enzymes, glycerol-3-phosphate dehydrogenase (GPDH); glyceraldehyde-3-phosphate dehydrogenase (GAPDH); triose phosphate isomerase (TPI) and Beta-hydroxyacid dehydrogenase (HAD). The first three enzymes interconnect a series of reactions between the upper part of glycolysis, fatty acid biosynthesis and the lower part of glycolysis. The genes for each have been isolated and their study will continue. We are planning a set of experiments to ascertain if the genes for enzymes on the glycolytic pathways are controlled as a set or whether they are controlled independently of one another. Transcripts and enzyme content will be measured in different cell types, in animals whose diet has been altered by carbohydrate, amino acid or lipid supplementation, and in different species of Drosophila that live in very different habitats. We are also planning to isolate the additional genes which encode other glycolytic enzymes. Our strategy will be to purify the protein, prepare an antiserum and screen recombinant DNA libraries of Drosophila cDNA cloned into the expression vector Lambdagt11. This approach has been used successfully to isolate the genes we are now studying. With clones of each gene and antibody for each protein we would begin studies to identify DNA sequences which are the site of regulation and to identify transcriptional factors which affect the expression of each of the genes and the entire set.