Lysine acetylproteome profiling under water deficit reveals key acetylated proteins involved in wheat grain development and starch biosynthesis

Lysine acetylation is a widespread protein posttranslational modification in all organisms. However, quantitative acetylproteome characterization in response to water deficit during crop grain development remains unknown. In the study, we performed the first large-scale acetylproteome analysis of developing wheat grains under water deficit using label-free quantitative proteome approach. In total, 716 acetylated sites corresponding to 442 acetylated proteins were identified, of which 106 acetylated sites representing 93 acetylated proteins (including 88 non-histones) showed significant changes under water-deficit. The functional classification showed that 57% and 20% of acetylated proteins were related to metabolic and cellular processes, respectively. Water-deficit caused widespread functional crosstalk between protein acetylation and other PTMs. Particularly, both acetylation and phosphorylation occurred in two key enzymes involved in starch biosynthesis, sucrose synthase (SuSy) and ADP glucose pyrophosphorylase (AGPase). Their crosstalk could play important roles in starch biosynthesis and yield formation under drought conditions. Western blot analysis combined with tandem mass spectrometry identification further verified the reliability of the acetylproteome results. Most of the acetylated proteins showed consistences between transcription and post-translation levels by quantitative real-time PCR. A putative metabolic pathway was proposed to dissect the roles of protein acetylation in regulation of drought response and defense during wheat grain development. Significance: Lysine acetylation is a widespread modification in all organisms. We performed the first large-scale acetylproteome analysis of developing wheat grains under water-deficit and revealed key acetylated proteins involved in wheat grain development and starch biosynthesis.