Proteome mismanagement along with age-dependent protein aggregation, oxidation and misallocation, likely leads to the overall functional decline in senescent organisms ( 3). The downturn of protein homeostasis (proteostasis), including the commonly observed slowdown of protein synthesis and degradation (protein turnover), is a major hallmark of aging ( 1, 2). Hence, we presume that maintenance of quality control mechanisms is a protective strategy in aging worms, although the ultimate proteome collapse is inescapable. Our data suggests increased heterogeneity of protein turnover of the translation machinery, whereas protein turnover of ubiquitin-proteasome and antioxidant systems are well-preserved over time. Decrease in protein turnover was consistent for only a minority of functionally related protein subsets, including tubulins and vitellogenins, whereas randomly diverging turnover patterns with age were the norm. Forty percent of the proteome shows gradual slowdown in turnover with age, whereas only few proteins show increased turnover. We followed changes in protein turnover at one-day resolution using a multiple-pulse 15N-labeling and accurate mass spectrometry approach. However, limited information is available on turnover dynamics at the individual protein level during aging. Protein turnover rates severely decline in aging organisms, including C.
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