Carbon Metabolism and the ROS Scavenging System Participate in Nostoc flagelliforme's Adaptive Response to Dehydration Conditions through Protein Acetylation.

Acetylation represents an extensively occurring protein post-translational modification (PTM) that plays a key role in many cellular physiological and biochemical processes. However, studies on PTMs such as acetylation of lysine (LysAc) in cyanobacteria are still rare. In this study, a quantitative LysAc approach (acetylome) on the strains of Nostoc flagelliforme subjected to different dehydration treatments was conducted. We observed that starch contents were significantly accumulated due to dehydration treatments, and we identified 2474 acetylpeptides and 1060 acetylproteins based on acetylome analysis. Furthermore, an integrative analysis was performed on acetylome and nontargeted metabolism, and the results showed that many KEGG terms were overlapped for both omics analyses, including starch and sucrose metabolism, transporter activity, and carbon metabolism. In addition, time series clustering was analyzed, and some proteins related to carbon metabolism and the ROS scavenging system were significantly enriched in the list of differentially abundant acetylproteins (DAAPs). These protein expression levels were further tested by qPCR. A working model was finally proposed to show the biological roles of protein acetylation from carbon metabolism and the ROS scavenging system in response to dehydration in N. flagelliforme. We highlighted that LysAc was essential for the regulation of key metabolic enzymes in the dehydration stress response.