Quantitative Acetylomics Reveals Substrates of Lysine Acetyltransferase GCN5 in Adult and Aging <i>Drosophila</i>

Protein lysine acetylation is a dynamic post-translational modification (PTM) that regulates a wide spectrum of cellular events including aging. General control nonderepressible 5 (GCN5) is a highly conserved lysine acetyltransferase (KAT). However, the acetylation substrates of GCN5 in vivo remain poorly studied, and moreover, how lysine acetylation changes with age and the contribution of KATs to aging remain to be addressed. Here, using Drosophila, we perform label-free quantitative acetylomic analysis, identifying new substrates of GCN5 in the adult and aging process. We further characterize the dynamics of protein acetylation with age, which exhibits a trend of increase. Since the expression of endogenous fly Gcn5 progressively increases during aging, we reason that, by combining the substrate analysis, the increase in acetylation with age is triggered, at least in part, by GCN5. Collectively, our study substantially expands the atlas of GCN5 substrates in vivo, provides a resource of protein acetylation that naturally occurs with age, and demonstrates how individual KAT contributes to the aging acetylome.蛋白质赖氨酸乙酰化（Protein lysine acetylation）是一类动态的翻译后修饰（post-translational modification, PTM），可调控包括衰老在内的诸多细胞生命活动。通用控制非阻遏蛋白5（General control nonderepressible 5, GCN5）是一类高度保守的赖氨酸乙酰转移酶（lysine acetyltransferase, KAT）。然而，目前对体内GCN5的乙酰化底物研究仍较为匮乏；此外，赖氨酸乙酰化如何随衰老发生动态变化，以及赖氨酸乙酰转移酶对衰老的调控贡献仍有待阐明。本研究以果蝇（Drosophila）为模型，开展无标记定量乙酰化组学分析，鉴定出成年个体及衰老过程中GCN5的新型底物。我们进一步表征了蛋白质乙酰化随衰老的动态变化趋势，发现其呈现逐步升高的态势。由于果蝇内源Gcn5的表达水平在衰老进程中持续上调，我们据此推测：衰老过程中乙酰化水平的升高至少部分由GCN5介导。综上，本研究大幅拓展了体内GCN5底物的图谱，提供了随自然衰老发生的蛋白质乙酰化相关研究资源，并阐明了单个赖氨酸乙酰转移酶如何调控衰老相关的乙酰化组。