Protein degradation rate in Arabidopsis thaliana leaf growth and development

We have applied 15N labeling approaches to leaves of the Arabidopsis thaliana rosette to characterize their protein degradation rate and understand its determinants. The progressive labeling of new peptides with 15N and measuring the decrease in the abundance of >60,000 existing peptides over time allowed us to define the degradation rate of 1228 proteins in vivo. We show that Arabidopsis protein half-lives vary from several hours to several months based on the exponential constant of the decay rate for each protein. This rate was calculated from the relative isotope abundance of each peptide and the fold change in protein abundance during growth. Protein complex membership and specific protein domains were found to be strong predictors of degradation rate, while N-end amino acid, hydrophobicity or aggregation propensity of proteins were not. We discovered rapidly degrading subunits in a variety of protein complexes in plastids and identified the set of plant proteins whose degradati...我们采用15N标记法（15N labeling approaches）对拟南芥（Arabidopsis thaliana）莲座叶的叶片进行实验，以表征其蛋白质降解速率并解析其决定因素。通过逐步利用15N标记新生肽段，并随时间监测超过60000种原有肽段的丰度下降情况，我们得以确定1228种蛋白质的体内（in vivo）降解速率。研究显示，拟南芥蛋白质的半衰期基于每种蛋白质降解速率的指数常数，范围可从数小时跨度至数月。该降解速率通过每种肽段的相对同位素丰度以及生长过程中蛋白质丰度的倍数变化计算得到。我们发现，蛋白质复合物成员身份与特定蛋白质结构域是降解速率的强预测因子，而蛋白质的N端氨基酸、疏水性或聚集倾向则并非如此。我们在质体（plastids）中的多种蛋白质复合物内发现了快速降解的亚基，并鉴定出一组降解……的植物蛋白质。