Mueller Susanne, Wahlander Asa, Selevsek Nathalie, Otto Claudia, Ngwa Elsy Mankah, Poljak Kristina, Frey Alexander D, Aebi Markus, Gauss Robert
Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich, Switzerland.
Functional Genomics Center Zurich, UZH/ETH Zurich, CH-8057 Zurich, Switzerland.
Mol Biol Cell. 2015 Jul 15;26(14):2596-608. doi: 10.1091/mbc.E15-03-0168. Epub 2015 May 20.
Protein degradation is essential for cellular homeostasis. We developed a sensitive approach to examining protein degradation rates in Saccharomyces cerevisiae by coupling a SILAC approach to selected reaction monitoring (SRM) mass spectrometry. Combined with genetic tools, this analysis made it possible to study the assembly of the oligosaccharyl transferase complex. The ER-associated degradation machinery compensated for disturbed homeostasis of complex components by degradation of subunits in excess. On a larger scale, protein degradation in the ER was found to be a minor factor in the regulation of protein homeostasis in exponentially growing cells, but ERAD became relevant when the gene dosage was affected, as demonstrated in heterozygous diploid cells. Hence the alleviation of fitness defects due to abnormal gene copy numbers might be an important function of protein degradation.
蛋白质降解对于细胞内稳态至关重要。我们开发了一种灵敏的方法，通过将稳定同位素标记氨基酸细胞培养法（SILAC）与选择反应监测（SRM）质谱联用，来检测酿酒酵母中的蛋白质降解速率。结合遗传工具，这种分析使得研究寡糖基转移酶复合物的组装成为可能。内质网相关降解机制通过降解过量的亚基来补偿复合物组分内稳态的紊乱。在更大规模上，发现内质网中的蛋白质降解在指数生长细胞的蛋白质内稳态调节中是一个次要因素，但当基因剂量受到影响时，内质网相关降解就变得重要了，如在杂合二倍体细胞中所证明的那样。因此，减轻由于异常基因拷贝数导致的适应性缺陷可能是蛋白质降解的一项重要功能。
