Structure and Function of a Novel Biotin Enzyme

本研究旨在了解生物素酶在植物新陈代谢中的意义和作用。为了实现这一目标，利用胡萝卜独特的体细胞胚胎发生系统对这些蛋白质进行了研究。在胡萝卜体细胞胚胎发育过程中，六种生物素多肽中的一种的稳态水平急剧升高。纯化了该生物素蛋白，并制备了多克隆抗体。利用这些抗体，已分离到编码该生物素蛋白的cDNA克隆。通过利用这些抗体和克隆的cDNAs作为特异性探针来研究这种新的生物素蛋白。这些研究集中在阐明这种生物素酶的功能和调节。抗体的初步实验已经确定这种生物素蛋白代表一种乙酰辅酶A羧基酶。这种形式的乙酰辅酶A羧基酶在植物代谢中的功能通过1)鉴定这种蛋白质在胡萝卜植株中的亚细胞和组织分布以及2)阐明调节这种蛋白质积累的分子遗传机制以响应发育和环境信号。生物素是一系列具有重要代谢功能的酶的重要组成部分。许多生物素酶的结构、功能和调节在不同的生物体中被广泛研究。然而，人们对植物的生物素酶知之甚少。为了更好地了解植物生物素酶在植物新陈代谢中的作用，本研究对含有生物素的酶的功能和调控进行了研究。

This research focuses on understanding the significance and role of biotin enzymes in plant metabolism. To achieve this goal the unique somatic embryogenesis system of carrot has been utilized to study these proteins. During the development of somatic embryos of carrot the steady state levels of one of the six biotin-containing polypeptides increases dramatically. This biotin protein has been purified and polyclonal antibodies against it have been prepared. Using these antibodies a cDNA clone coding for this biotin protein has been isolated. This novel biotin protein is being investigated through the utilization of these antibodies and the cDNA clone as specific probes to investigate this novel biotin protein. These investigations concentrate on elucidating the function and regulation of this biotin enzyme. Initial experiments with the antibodies have identified this biotin protein as representing an acetyl CoA carboxylase. The function of this form of acetyl-CoA carboxylase in plant metabolism is being elucidated by 1) identifying the subcellular and tissue distribution of this protein in the carrot plant and 2) elucidating the molecular genetic mechanisms that regulate the accumulation of this protein in response to developmental and environmental signals. Biotin is an essential component of a set of enzymes that have important metabolic functions. The structure, function and regulation of a number of biotin enzymes is extensively studied in a diverse set of organisms. However, very little is known about the biotin enzymes of plants. This research investigates the function and regulation of plant biotin- containing enzymes in order to provide a better understanding of their role in plant metabolism.***//