Ph.D. 1998, Florida State University, Tallahassee
1. Elucidation of the missing steps on the flavin biosynthetic pathway in plants. Flavin cofactors FMN and FAD are required by proteins participating in a wide variety of essential metabolic processes. Investigating enzymes needed for biosynthesis of these cofactors is one of the major current focus areas for the laboratory. We have already identified and characterized several enzymes involved in the interconversions of riboflavin, FMN and FAD and in biosynthesis of riboflavin, and are continuing this work with the aim to build a complete map of flavin nucleotide metabolism in plants.
2. Exploration of the roles of intracellular flavin levels in plant growth, development, and stress resistance. The many enzymes that require flavin cofactors vary in their affinity for these cofactors. Because flavin levels in plant cells are low, different enzymes are saturated with the cofactors to a different degree. We are interested in finding out whether variations in flavin cofactor levels in plant cells contribute to regulation of growth, development, and stress resistance by simultaneously modifying activity of multiple enzymes, and thus fluxes through multiple pathways. We are collaborating with Dr. Hanjo Hellmann (WSU), who is interested in answering similar questions for pyridoxal phosphate.
3. Characterization of cytosolic phosphatases of the haloacid dehalogenase superfamily. We are interested in finding out whether these enzymes, which hydrolyze mostly sugar phosphates and nucleotide phosphates, play a role in maintaining phosphate homeostasis, and whether they affect phosphate use efficiency, in plants. Phosphate is an essential macronutrient for plants and is commonly added as a fertilizer to crops. Improved phosphate use efficiency would benefit agriculture and the environment by lowering the need for adding phosphate fertilizers and by reducing the resulting pollution.
4. Metabolism of tetrahydrofolate-bound one-carbon units in plants. One-carbon units passing through the folate pathway ultimately end up in a wide variety of molecules including proteins, DNA, RNA, and numerous methylated secondary metabolites. We are investigating enzymes required to ensure uninterrupted supply of these units from the amino acid serine (serine hydroxymethyltransferase) and from formate (formate-tetrahydrofolate ligase).
5. Flavins in α-proteobacteria. We are currently studying enzymes involved in flavin biosynthesis in the legume symbiont Sinorhizobium meliloti and in the mammalian intracellular pathogen Brucella abortus. We are also interested in finding out whether secreted flavins play important roles in the Medicago – S. meliloti symbiosis. This project is done in collaboration with Dr. Svetlana Yurgel (WSU), a microbial geneticist.
6. Arsenic in lentils. This multidisciplinary, collaborative effort is aiming to find ways to decrease accumulation of arsenic in edible parts of lentils grown in contaminated soils in South East Asia (India, Bangladesh). In collaboration with Dr. Lynne Carpenter-Boggs (WSU), Dr. Paul Buckley (Lewis-Clark State College), Dr. Claire Coyne (USDA, WSU), Dr. Jim Harsh (WSU), Dr. Dorrie Maine (WSU), and Dr. Rebecca McGee (USDA, WSU).