RUI: Regulation of the Pyrimidine Pathway in Plants

9318479 Slocum嘧啶核苷酸是DNA和RNA合成的前体，嘧啶衍生物在许多其他类型的生物合成中是活化的中间体。这些过程对所有生物的生长和发育具有根本的重要性。在植物中，人们对各种调节嘧啶生物合成的机制知之甚少，但大多数证据表明，重要的调控位点是该途径的第一步和/或第二步，涉及酶氨甲酰磷酸合成酶（CPSase）和天冬氨酸转氨基甲酰化酶（ATCase）。本研究的目的是探讨在植物中调节这些酶活性的各种分子机制。这将通过克隆CPSase和ATCase基因，纯化和生化表征酶蛋白，以及生产CPSase和ATCase特异性抗血清来实现。核酸和抗体探针将用于研究编码CPSase和ATCase的基因在不同植物组织中的表达，以及对可能影响嘧啶生物合成的各种处理的响应。编码CPSase和ATCase的基因将在大肠杆菌carA/B-和pyrB-突变体中进行功能互补克隆。这种方法已经允许成功分离两个不同的基因（pyrB1和pyrB2）编码功能性的豌豆ATCases。这种植物是第一个在一个以上的pyrB基因中被证实的生物。＊＊＊

9318479 Slocum Pyrimidine nucleotides are precursors of DNA and RNA synthesis and pyrimidine derivatives are activated intermediates in many other types of biosyntheses. These processes are of fundamental importance to the growth and development of all living organisms. In plants, little is known about the various mechanisms which regulate pyrimidine biosynthesis, but most evidence suggests that the important sites of regulation are the first and/or second steps of the pathway, involving the enzymes carbamoylphosphate synthetase (CPSase) and aspartate transcarbamoylase (ATCase). The objective of this research is to investigate the various molecular mechanisms regulating the activity of these enzymes in plants. This will be accomplished by cloning the genes for CPSase and ATCase, purifying and biochemically characterizing the enzyme proteins, and producing CPSase and ATCase-specific antisera. The nucleic acid and antibody probes will be used to investigate expression of the genes encoding CPSase and ATCase in different plant tissues and in response to various treatments that would be expected to impact pyrimidine biosynthesis. The genes encoding CPSase and ATCase will be cloned by functional complementation in E. coli carA/B- and pyrB- mutants. This approach has already permitted the successful isolation of two different genes (pyrB1 and pyrB2) encoding functional ATCases in pea. This plant is the first organism in which more than one pyrB gene has been demonstrated. ***