Arabidopsis 2010: Functional Analysis of the Arabidopsis Yellow Stripe-Like (YSL) Family: Heavy Metal Transport and Partitioning Via Metal-nicotianamine Complexes

该项目涉及一个名为YELLOW STRIPE-LIKE （YSL）的金属转运蛋白家族，该家族已被确定为与玉米YS1蛋白具有很强的序列相似性。YS1的主要功能是从土壤中吸收铁。然而，与其他已知的植物铁转运蛋白不同，YS1转运的铁是由特定的植物来源的铁（III）螯合剂（称为植物铁载体）络合而成的。拟南芥基因组中编码了8个YSL蛋白（http://www.bio.umass.edu/biology/ewalker），但它们不能在植物铁载体摄取中发挥作用，因为拟南芥（像所有非草类植物一样）既不能合成也不能利用植物铁载体。拟南芥确实制造和使用一种相关的化合物，尼古丁胺，这是植物铁载体的生物合成前体。初步证据表明，YSL蛋白介导了与烟胺结合的金属的运输。烟胺在植物体内实现适当金属离子分配中的许多作用尚不完全清楚，但有强有力的证据表明，烟胺是铁、锌和锰通过韧皮部分配所必需的，也是铜在木质部运输所必需的。8个拟南芥YSL基因的功能将被确定，从最窄的功能定义-生化功能，到最宽的功能定义-这些蛋白质在植物生长发育中的作用。将形成对每个YSL蛋白功能的全面描述，从而回答以下问题：哪些金属由YSL蛋白运输？哪些细胞表达每种YSL并因此参与这些金属的运输？哪些营养条件影响YSL家族成员的表达？去除特定的YSL基因会如何影响植物中金属离子的分布模式？通过整合所有8个YSL基因的特定信息，我们对植物使用的金属离子分配机制的理解将大大提高。序列信息将立即通过Genbank和项目网站提供。该网站还将更新每个YSL基因的实验数据，因为它是可用的。

This project concerns a family of metal transporters called YELLOW STRIPE-LIKE (YSL), which have been identified based on their very strong sequence similarity to the YS1 protein of maize. The function of YS1 is in the primary uptake of iron from the soil. However, unlike other known plant iron transporters, YS1 transports iron that is complexed by specific plant-derived Fe(III) chelators called phytosiderophores. There are eight YSL proteins encoded in the Arabidopsis thaliana genome (http://www.bio.umass.edu/biology/ewalker), but they cannot function in phytosiderophore uptake, since Arabidopsis (like all non-grasses) can neither synthesize nor use phytosiderophores. Arabidopsis does make and use a related compound, nicotianamine, which is the biosynthetic precursor to phytosiderophores. Preliminary evidence suggests that YSL proteins mediate transport of metals bound to nicotianamine. The many roles of nicotianamine in achieving proper metal ion allocation in plants are incompletely understood, but there is strong evidence that nicotianamine is necessary for distribution of Fe, Zn, and Mn via phloem, and that it is required for transport of Cu in xylem. The functions of the eight Arabidopsis thaliana YSL genes will be determined from the narrowest definition of function-biochemical function, to the broadest definition of function-the role of these proteins in the growth and development of the plant. A comprehensive description of the function of each YSL protein will be formed that will answer these questions: Which metals are transported by YSL proteins? Which cells express each YSL and therefore are involved in transporting these metals? Which nutrient conditions affect expression of each YSL family member? In what way(s) does abolishing specific YSL genes affect the pattern of metal ion distribution in the plant? By integrating this specific information for all eight YSL genes, our understanding of the metal ion allocation mechanisms used by plants will be greatly improved. Sequence information will be made immediately available through Genbank and on the project website. The website will also be updated with experimental data for each YSL gene as it becomes available.