In order to understand the cellular processes which regulate glyoxysome biogenesis, Dr. Harada is studying the mechanisms which regulate accumulation of the glyoxysome-specific enzymes, isocitrate lyase and malate synthase. enzyme activity appears to be controlled at the level of mRNA accumulation, preliminary studies suggest that primary control occurs at the transcriptional level. The immediate objective is to identify the regulatory elements and DNA binding factors which regulate the two genes. Regulatory elements will be identified by gene expression in transgenic plants. Trans-acting factors will be studied by identifying and isolating DNA binding proteins and by selecting mutation in genes encoding the factors. Characterizing the sequence elements and factors regulating isocitrate lyase and malate synthase genes will provide insight into the control of a germination-related process. %%% Glyoxysomes are specialized subcellular organelles which serve a critical role during seed germination and seedling growth. The enzymes which break down stored lipids to provide nutrients for seedlings are stored in this organelle. Formation of glyoxysomes is highly developmentally regulated; they are only present in developing seeds and in seedling and are not present in mature plant organs. This study will elucidate mechanisms involved in this regulation.
