Gene Regulation in Glyoxysome Biogenesis

Glyoxysomes是一种特殊的过氧化物酶体，它含有动员脂质所必需的酶。为了研究细胞器的生物发生过程，原田博士正在研究编码异柠檬酸裂解酶和苹果酸合成酶的基因的调控，这两种glyoxylate cycle酶只与glyoxysomes相关。这些基因在发育过程中受到调控；它们在幼苗、发育中的种子、衰老器官和花粉中表达，但在成熟植物的非衰老器官中不表达。此外，基因的调控主要发生在转录水平。该提案的长期目标是确定调节这些基因的生理信号，从而控制糖酶体的生物发生。另一个目标是确定一个共同的信号是否在植物生命周期的不同时期调节这些基因。提出了两种主要方法来解决这些问题。首先，原田博士将定位顺式作用元件，并识别与这些元件相互作用的DNA结合蛋白，以获得对基因调控的机制理解。其次，他将识别基因表达改变的突变体，开始定义基因调节途径的组成部分。他预计，这些补充研究最终将提供深入了解控制乙氧化酶体生物发生的生理线索。

Glyoxysomes are specialized peroxisomes that contain enzymes critically required for the mobilization of lipids. To study processes involved in the biogenesis of the organelle, Dr. Harada is investigating the regulation of genes encoding isocitrate lyase and malate synthase, two glyoxylate cycle enzymes that are associated exclusively with glyoxysomes. The genes are regulated developmentally; they are expressed in seedlings, developing seeds, senescent organs, and in pollen but not in non-senescent organs of the mature plant. Moreover, regulation of the genes occurs primarily at the transcriptional level. The proposal's long term goal is to define the physiological signals that regulate these genes, and, therefore, control glyoxysome biogenesis. An accompanying objective is to determine whether a common signal regulates these genes at different periods of the plant life cycle. Two primary approaches are proposed to address these issues. First, Dr. Harada will localize cis-acting elements and identify the DNA binding proteins that interact with these elements to obtain a mechanistic understanding of the regulation of the genes. Second, he will identify mutants altered in the expression of the genes to begin to define components of the pathway regulating the genes. He anticipates that these complementary studies ultimately will provide insight into the physiological cues that control glyoxysome biogenesis.