Gene Regulation in Glyoxysome Biogenesis

为了了解调控糖氧体生物发生的细胞过程，原田博士正在研究调控乙氧基体特异酶、异柠檬酸裂解酶和苹果酸合成酶积累的机制。酶活性似乎控制在mRNA积累的水平上，初步研究表明，主要控制发生在转录水平上。目前的目标是确定调控这两个基因的调控元件和DNA结合因子。调控元件将通过转基因植物中的基因表达来确定。反式作用因子将通过鉴定和分离DNA结合蛋白以及在编码因子的基因中选择突变来研究。鉴定调控异柠檬酸裂解酶和苹果酸合成酶基因的序列元件和因子将有助于深入了解与萌发相关的过程的控制。乙二醇体是一种特殊的亚细胞器，在种子萌发和幼苗生长过程中起着至关重要的作用。分解储存的脂类为幼苗提供营养的酶储存在这个细胞器中。糖氧体的形成是高度发育调节的；它们只存在于发育中的种子和幼苗中，而不存在于成熟的植物器官中。这项研究将阐明这一调控的机制。

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.