This is an award under the Small Grant for Exploratory Research program. The immediate objective of the project is to isolate and characterize genes encoding two enzymes (ATP sulfurylase and APS kinase) that are involved in the first step in the sulfur assimilation pathway using Arabidopsis thaliana as an experimental system. The long-term objective is to understand the biology of sulfur in higher plants. Sulfur is an essential nutrient required by all organisms. Plants and microorganisms reduce inorganic sulfate to a variety of organic compounds, and they provide animals with a source of organic sulfur. Animals including humans require sulfur, yet do not have the ability to convert inorganic sulfur to organic compounds. The role of sulfur is diverse, including an essential component of amino acids, some regulatory molecules and lipids. In addition, plants' ability to metabolize sulfur is potentially significant in ameliorating sulfur toxicity in the environment. Despite its obvious significance, very little is known about the sulfur pathway in higher plants, or the mechanisms by which sulfur mediates important cellular functions. This research may help open up a new field of research in biology.
