ANTIOXIDANT METABOLISM IN CHLAMYDOMONAS

在所有的细胞中都不可避免地产生了活性氧(ROS)。 细菌、植物和动物中的需氧生物。应对 ROS生成的潜在破坏性后果是一个问题 具有广泛的生物学意义。激动不已、高度参与的 氧合光合作用中的活性中间体带来了独特的问题 对于藻类和植物来说，与RO的产生有关。这个 拟议的研究计划集中在如何进行光合作用的问题上 生物体可以防止或减少由ROS引起的光氧化损伤。至 解剖叶绿体中的抗氧化防御，突变体 分离到单细胞绿藻--莱茵衣藻。 几个突变体影响叶黄素色素的代谢， 在所有藻类和植物中具有关键的光保护作用。Npq1 缺乏叶黄素和玉米黄质的双突变体， 在强光下经历光氧化漂白，可能是由于 增加ROS的产量和/或减少ROS的猝灭，特别是 单线态氧。这项拟议的研究将检查照片的类型- 氧化损伤与不同抗氧化系统的反应 Npq1lor1细胞。叶黄素影响基因的分离 突变体将能够确定突变体的分子基础。 表型，并将为进一步的遗传 分析，包括分离npq1lor1的抑制子。这个 其他RO的产生和/或清除在另一组中被干扰 突变体，这将使用分子组合来表征 遗传、生化和生理学方法。了解 叶黄素等抗氧化剂在藻类中的代谢和功能 植物将提供对这些重要作用的洞察 预防黄斑等老年性疾病的分子 人类的退化并将使抗氧化剂的工程成为可能 有利于人类营养和健康的植物新陈代谢。

Reactive oxygen species (ROS) are generated inevitably in cells of all aerobic organisms, from bacteria plants and animals. Coping with the potentially damaging consequences of ROS generation is a problem of broad biological significance. The involvement of excited and highly reactive intermediates in oxygenic photosynthesis poses unique problems for algae and plants with respect to the generation of ROS. The proposed research plan is focused on the question of how photosynthetic organisms prevent or minimize photo-oxidative damage caused by ROS. To dissect antioxidant defenses in the chloroplast, mutants of the unicellular green alga Chlamydomonas reinhardtii, have been isolated. Several mutants affect the metabolism of xanthophyll pigments, which have critical roles in photoprotection in all algae and plants. An npq1 lor1 double mutant, which is deficient in lutein and zeaxanthin, undergoes photo-oxidative bleaching in high light, presumably due to increased production and/or decreased quenching of ROS, especially singlet oxygen. The proposed research will examine the types of photo- oxidative damage and the responses of various antioxidant systems in npq1 lor1 cells. Isolation of the genes affected in the xanthophyll mutants will enable determination of the molecular basis for the mutant phenotypes and will provide a strong foundation for further genetic analysis, including isolation of suppressors of npq1 lor1. The generation and/or scavenging of other ROS is perturbed in another group of mutants, which will be characterized using a combination of molecular genetic, biochemical, and physiological approaches. Understanding the metabolism and function of xanthophylls and other antioxidants in algae and plants will provide insights into the important roles of these molecules in preventing age-related diseases such as macular degeneration in humans and will enable engineering of antioxidant metabolism in plants to benefit human nutrition and health.