Physiological Functions and Biochemical Properties of Plant Cytochromes b561

建议：抗坏血酸(维生素C)有能力保护植物免受干旱、伤害、暴露于污染物、高盐和病原体攻击等逆境的破坏性影响。此外，它是许多代谢酶的辅因子，并参与植物激素的生物合成。因此，抗坏血酸在控制植物生长发育、抵御病原菌和氧化胁迫以及调节细胞氧化还原状态等方面发挥着关键作用。虽然人们对抗坏血酸的生物合成和分解代谢的了解正在迅速扩大，但人们对抗坏血酸的作用机制以及它是如何再生的知之甚少。本研究的目的是以拟南芥为模型系统，研究一类新发现的细胞膜蛋白细胞色素b561在抗坏血酸代谢和再生中的生理作用。在前人工作的基础上，中心假说是，细胞色素T细胞生长因子b561以抗坏血酸为电子供体，通过催化跨膜电子传递参与抗坏血酸介导的细胞过程。在这个反应中，部分氧化的抗坏血酸(单脱氢抗坏血酸)可以被重新还原为抗坏血酸，从而补充细胞抗坏血酸库。本研究的目的将通过：1)确定拟南芥细胞色素b561的时空表达模式；2)通过改变其表达水平来确定其生理功能；3)确定拟南芥细胞色素b561的生化特性。这项拟议的研究意义重大，因为它针对的是一类研究较少的膜蛋白，这些蛋白参与了抗坏血酸介导的反应。深入了解这些蛋白质的功能有助于我们理解植物体内抗坏血酸的调节和代谢。更广泛的影响：国际和平研究所实验室的多学科方法为学生和博士后研究人员的培训和专业发展提供了机会。国际和平协会将参加面向代表性不足群体的大学外联方案，这项工作的结果将得到广泛传播。

Proposal: 0416742ABSTRACTAscorbate (vitamin C) has the ability to protect plants against the damaging affects of stress situations, such as drought, wounding, exposure to pollutants, high salt and pathogen attack. In addition, it is a cofactor to numerous metabolic enzymes and is involved in the biosynthesis of plant hormones. Therefore, ascorbate plays a key role in the control of plant growth and development, defense against pathogens and oxidative stress and in the regulation of cellular redox status.While knowledge of ascorbate biosynthesis and catabolism is rapidly expanding, little is known about the mechanisms by which ascorbate exerts its effects, and how it is regenerated. The objective of the current proposal is to determine the physiological role of a newly-identified class of membrane proteins, cytochromes (Cyts) b561, in ascorbate metabolism and regeneration, using Arabidopsis thaliana as a model system. Based on previous work, the central hypothesis is that Cyts b561 contributes to ascorbate-mediated cellular processes by catalyzing trans-membrane electron transport with ascorbate as the electron donor. Partially-oxidized ascorbate (mono-dehydroascorbate) can be re-reduced to ascorbate in this reaction, thereby replenishing cellular ascorbate pools. The objective of this proposal will be attained by: 1) determining the spatial and temporal expression patterns of A. thaliana Cyts b561; 2) determining the physiological role of Cyts b561 by altering its expression levels, and 3) determining the biochemical properties of A. thaliana Cyts b561. The proposed research is significant in that it is aimed at a class of poorly-studied membrane proteins involved in ascorbate-mediated reactions. Insight into the function of these proteins should contribute to our understanding of ascorbate regulation and metabolism in plants. Broader Impacts: The multidisciplinary approaches in the laboratory of the PI provide an opportunity for training and professional development of students and postdoctoral researchers. The PI will take part in university outreach programs to underrepresented groups, and results from this work will be broadly disseminated.