Boyd Stefanie D, Ullrich Morgan S, Calvo Jenifer S, Behnia Fatemeh, Meloni Gabriele, Winkler Duane D
Department of Biological Sciences, the University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080, USA.
Department of Chemistry and Biochemistry, the University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080, USA.
Molecules. 2020 Feb 28;25(5):1086. doi: 10.3390/molecules25051086.
Zinc (II) ions (hereafter simplified as zinc) are important for the structural and functional activity of many proteins. For Cu, Zn superoxide dismutase (Sod1), zinc stabilizes the native structure of each Sod1 monomer, promotes homo-dimerization and plays an important role in activity by "softening" the active site so that copper cycling between Cu(I) and Cu(II) can rapidly occur. Previously, we have reported that binding of Sod1 by its copper chaperone (Ccs) stabilizes a conformation of Sod1 that promotes site-specific high-affinity zinc binding. While there are a multitude of Sod1 mutations linked to the familial form of amyotrophic lateral sclerosis (fALS), characterizations by multiple research groups have been unable to realize strong commonalities among mutants. Here, we examine a set of fALS-linked Sod1 mutations that have been well-characterized and are known to possess variation in their biophysical characteristics. The zinc affinities of these mutants are evaluated here for the first time and then compared with the previously established value for wild-type Sod1 zinc affinity. Ccs does not have the same ability to promote zinc binding to these mutants as it does for the wild-type version of Sod1. Our data provides a deeper look into how (non)productive Sod1 maturation by Ccs may link a diverse set of fALS-Sod1 mutations.
锌离子(以下简称为锌)对许多蛋白质的结构和功能活性至关重要。对于铜锌超氧化物歧化酶(Sod1)而言,锌可稳定每个Sod1单体的天然结构,促进同二聚化,并通过“软化”活性位点在其活性方面发挥重要作用,从而使铜在Cu(I)和Cu(II)之间快速循环。此前,我们曾报道Sod1的铜伴侣蛋白(Ccs)与Sod1的结合可稳定Sod1的一种构象,该构象促进位点特异性高亲和力锌结合。虽然有众多与家族性肌萎缩侧索硬化症(fALS)相关的Sod1突变,但多个研究小组的表征未能在这些突变体之间发现强烈的共性。在此,我们研究了一组已得到充分表征且已知其生物物理特性存在差异的与fALS相关的Sod1突变。本文首次评估了这些突变体的锌亲和力,然后将其与先前确定的野生型Sod1锌亲和力值进行比较。Ccs促进锌与这些突变体结合的能力与促进锌与野生型Sod1结合的能力不同。我们的数据更深入地揭示了Ccs介导的(非)有效Sod1成熟过程可能如何将多种fALS-Sod1突变联系起来。