METAL BINDING TO PLANT METALLOTHIONEINS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 植物金属硫蛋白（MT）是一类普遍存在的蛋白质，在金属离子的体内平衡、解毒和植物发育中具有特定的但大多数仍未知的作用。植物MT是低分子量、富含半胱氨酸的蛋白质，具有极高的金属离子含量（高达7质量当量）。与哺乳动物的对应物相比，关于植物MT的可用信息相当有限，这一领域的研究活动最近才开始增加[例如1]。也是在今年，我们的团队确定了植物MT的第一个三维结构，特别是种子特异性小麦Zn 6 Ec-1蛋白的较大结构域。虽然我们现在有简明的数据，每个蛋白质的金属离子的数量在手的MT从四个不同的植物MT亚组的数量，配位体的性质并不总是很清楚。虽然金属离子主要结合在四面体四硫醇配位环境中，偶尔发现高度保守的His残基，这可能也起作用。我们也有越来越多的证据表明，存在额外的金属离子结合位点，具有较低的亲和力。Cys残基在这种新的配位模式中仅起次要作用是非常可行的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Plant metallothioneins (MTs) are a ubiquitous class of proteins with a specific but mostly still unknown role in metal ion homeostasis, detoxification, and plant development. Plant MTs are low molecular mass, cysteine-rich proteins with an extremely high metal ion content (up to 7 mass equivalents). In contrast to their mammalian counterparts, the information available about plant MTs are rather limited and research activities in this area only started to increase recently [e.g. 1]. It was also only this year that our group determined the first three dimensional structure of a plant MT, specifically of the larger domain of the seed-specific wheat Zn6Ec-1 protein. While we have now concise data about the number of metal ions per protein at hand for a number of MTs from the four different plant MT subgroups, the nature of the coordinating ligands is not always clear. While metal ions are predominantly bound in tetrahedral tetrathiolate coordination environments, occasionally highly conserved His residues are found, which might play a role as well. We also have increasing evidence for the existence of additional metal ion binding sites with lower affinity. It is very well feasible that Cys residues have only a minor role in this new coordination mode.