RUI: Understanding Cu(I) Interactions with Zinc-Metalloproteins: Impact of Cu(I) on Structure and Function of the X-Linked Inhibitor of Apoptosis Protein

这一奖项由生命过程化学项目授予Macalester学院的Kathryn Splan教授，支持研究铜离子与锌结合蛋白的相互作用。许多蛋白质需要金属离子才能发挥正常的功能，而用具有不同化学性质的金属离子取代通常的金属离子可能会改变蛋白质的结构，从而改变蛋白质的功能。虽然金属离子替代在金属离子毒性的背景下有明显的影响，但金属离子替代后蛋白质功能的变化也可能构成一种理想的功能策略。这些实验揭示了锌蛋白对铜替代的敏感性，并表征了这种替代对蛋白质功能的影响。该项目对学生进行生化准备和表征技术方面的培训，从而培养扎实的技术技能，为进一步学习和/或进入劳动力大军做准备。该项目的结果也为细胞生物学、神经化学和神经生物学领域提供了信息，特别是在那些与疾病的分子基础相关的领域，这些疾病的特征是金属离子水平调节不当。在这项工作中，通过表征铜(I)与X-连锁的凋亡抑制蛋白(XIAP)的相互作用，进一步研究了铜(I)对金属蛋白功能的影响。XIAP是一种最近参与铜稳态的锌(II)金属蛋白。由于这两种金属离子具有相同的亲硫性，多个锌(II)蛋白质结构基序容易被铜(I)置换。在XIAP的锌(II)结构位上的铜(I)取代是一种可能的机制，通过改变铜浓度来调节XIAP的功能。利用各种光谱和生化方法来检测添加铜后锌离子的置换以及由此引起的结构和功能变化。在分子水平上了解铜(I)与这一目标的相互作用，加深了对金属蛋白对铜(I)破坏敏感性的理解，并澄清了铜(I)在XIAP功能中的作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award from the Chemistry of Life Processes Program to Profesor Kathryn Splan of Macalester College supports research that investigates the interaction of copper ions with zinc-binding proteins. Many proteins require metal ions for proper function, and replacement of the usual metal ion with one exhibiting different chemical properties is likely to alter protein structure, and therefore, function. While metal-ion substitution has clear ramifications in the context of metal-ion toxicity, changes in protein function upon metal-ion substitution may also constitute a desirable functional strategy. The experiments reveal the susceptibility of zinc proteins toward substitution by copper and characterize the impact of this substitution on the protein's function. The project trains students in biochemical preparation and characterization techniques, thereby building solid technical skills in preparation for further study and/or entry into the work force. The results from the project also inform the fields of cell biology, neurochemistry, and neurobiology, particularly in those areas concerned with the molecular basis of diseases that are characterized by mis-regulated metal ion levels.In this work, the impact of Cu(I) on metalloprotein function is further investigated by characterizing the interaction of Cu(I) with the X-linked Inhibitor of Apoptosis Protein (XIAP), a Zn(II)-metalloprotein recently implicated in copper homeostasis. Multiple Zn(II) protein structural motifs have been shown to be susceptible to displacement by Cu(I), owing to the shared thiophilic character of both metal ions. Cu(I) substitution at the Zn(II) structural sites of XIAP is one possible mechanism by which XIAP function may be modulated by changing copper concentrations. A variety of spectroscopic and biochemical approaches are utilized to detect the displacement of zinc ions upon the addition of copper and the resulting structural and functional changes. Understanding Cu(I) interactions with this target at the molecular level deepens the understanding of metalloprotein susceptibility toward disruption by Cu(I) in general and clarifies the role of Cu(I) in XIAP function.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.