Department of Biology, University of Crete, Vasilika Vouton, P. O. Box 2208, 70013, Heraklion, Crete, Greece.
Computational Genomics Group, Biomedical Sciences Research Center "Alexander Fleming", 16672, Athens, Greece.
Curr Genet. 2023 Feb;69(1):41-53. doi: 10.1007/s00294-022-01258-8. Epub 2022 Dec 1.
Although copper is an essential trace element for cell function and viability, its excess can lead to protein oxidation, DNA cleavage, and ultimate cell damage. Cells have established a variety of regulatory mechanisms to ensure copper ion homeostasis. In Saccharomyces cerevisiae, copper sensing and response to copper deficiency are regulated by the transcription factor Mac1. Our group has previously reported that in addition to copper, several chromatin proteins modulate Mac1 functionality. In this study, based on a synthetic growth deficiency phenotype, we showed that the Cu/Zn superoxide dismutase Sod1 plays an important role in Mac1 transcriptional activity, in unchallenged nutrient-rich growth conditions. Sod1 is a multipotent cytoplasmic and mitochondrial enzyme, whose main known function is to detoxify the cell from superoxide ions. It has been previously reported that Sod1 also enters the nucleus and affects the transcription of several genes, some of which are involved in copper homeostasis under Cu-depleted (Wood and Thiele in J Biol Chem 284:404-413, 2009) or only under specific oxidative stress conditions (Dong et al. Mol Cell Biol 33:4041-4050, 2013; Tsang et al. Nar Commun 8:3446, 2014). We have shown that Sod1 physically interacts with Mac1 transcription factor and is important for the transactivation as well as its DNA-binding activities. On the other hand, a constitutively active mutant of Mac1 is not affected functionally by the Sod1 ablation, pointing out that Sod1 contributes to the maintenance of the copper-unchelated state of Mac1. In conclusion, we showed that Sod1-Mac1 interaction is vital for Mac1 functionality, regardless of copper medium deficiency, in unchallenged growth conditions, and we suggest that Sod1 enzymatic activity may modify the redox state of the cysteine-rich motifs in the Mac1 DNA-binding and transactivation domains.
虽然铜是细胞功能和生存的必需微量元素，但过量的铜会导致蛋白质氧化、DNA 断裂，最终导致细胞损伤。细胞已经建立了各种调节机制来确保铜离子的体内平衡。在酿酒酵母中，铜感应和对铜缺乏的反应受转录因子 Mac1 的调节。我们的研究小组之前报道过，除了铜之外，几种染色质蛋白也调节 Mac1 的功能。在这项研究中，基于合成的生长缺陷表型，我们表明 Cu/Zn 超氧化物歧化酶 Sod1 在未受挑战的富含营养的生长条件下对 Mac1 的转录活性起着重要作用。Sod1 是一种多功能的细胞质和线粒体酶，其主要已知功能是从细胞中清除超氧阴离子。先前有报道称，Sod1 也进入细胞核并影响几个基因的转录，其中一些基因在铜缺乏（Wood 和 Thiele 在 J Biol Chem 284:404-413, 2009）或仅在特定的氧化应激条件下（Dong 等人，Mol Cell Biol 33:4041-4050, 2013；Tsang 等人，Nar Commun 8:3446, 2014）参与铜稳态。我们已经表明，Sod1 与 Mac1 转录因子发生物理相互作用，对其转录激活和 DNA 结合活性都很重要。另一方面，Mac1 的组成性激活突变体的功能不受 Sod1 缺失的影响，这表明 Sod1 有助于维持 Mac1 的非螯合铜状态。总之，我们表明，Sod1-Mac1 相互作用对于 Mac1 的功能至关重要，无论在未受挑战的生长条件下铜是否缺乏，我们还表明 Sod1 的酶活性可能会改变 Mac1 DNA 结合和转录激活结构域中富含半胱氨酸的基序的氧化还原状态。
