Ottawa Hospital Research Institute, Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital, Ottawa, Ontario, Canada, K1H8L6.
J Proteomics. 2013 Apr 9;81:24-30. doi: 10.1016/j.jprot.2013.01.014. Epub 2013 Jan 30.
Proteostasis, the process of balancing protein production with protein degradation is vital to normal cell function. Defects within the mechanisms that control proteostasis lead to increased content of a specialized insoluble protein fraction that forms dense aggregates within the cell. We have previously implicated the Saccharomyces cerevisiae metacaspase Yca1 as an active participant in maintaining proteostasis, whereby Yca1 acts to limit aggregate content. Here, we further characterized the proteostasis role of Yca1 by conducting proteomic analysis of the insoluble protein fraction in wildtype and Yca1 knockout cells, under normal and heat stressed conditions. Our findings suggest that the composition of insoluble protein fraction is non-specific and comprises a wide array of protein species rather than a limited repertoire of aggregate susceptible proteins or peptides. Interestingly, the loss of Yca1 led to a significant decrease of proteins that control ribosome biogenesis and protein synthesis within the insoluble fraction, indicating that the cell may invoke a compensatory mechanism to limit protein production during stress, a feature dependent on Yca1 activity. Finally, we noted that protein degradation factors such as Cdc48 co-localize with Yca1 to the insoluble fraction, supporting the hypothesis that Yca1 may act primarily to dissolve or reduce accumulated aggregates. This article is part of a Special Issue entitled: From protein structures to clinical applications.
蛋白质稳态是指平衡蛋白质生成与降解的过程，对于细胞的正常功能至关重要。控制蛋白质稳态的机制缺陷会导致特定不溶性蛋白质部分的含量增加，从而在细胞内形成密集的聚集体。我们之前已经表明，酿酒酵母的 metacaspase Yca1 是维持蛋白质稳态的积极参与者，Yca1 可限制聚集体的含量。在这里，我们通过对野生型和 Yca1 敲除细胞在正常和热应激条件下的不可溶性蛋白质部分进行蛋白质组学分析，进一步研究了 Yca1 的蛋白质稳态作用。我们的研究结果表明，不可溶性蛋白质部分的组成是非特异性的，包含广泛的蛋白质种类，而不是有限的聚集体敏感蛋白或肽谱。有趣的是，Yca1 的缺失导致不可溶性部分中控制核糖体生物发生和蛋白质合成的蛋白质显著减少，表明细胞在应激期间可能会调用补偿机制来限制蛋白质的产生，这一特征依赖于 Yca1 的活性。最后，我们注意到蛋白降解因子如 Cdc48 与 Yca1 共定位于不可溶性部分，这支持了 Yca1 可能主要通过溶解或减少积累的聚集体来发挥作用的假设。本文是一个特刊的一部分，主题为：从蛋白质结构到临床应用。
