Oxidative stress-triggered interactions between the succinyl- and acetyl-proteomes of rice leaves

Protein lysine acylations, such as succinylation and acetylation, are important post-translational modification (PTM) mechanisms, with key roles in cellular regulation. Antibody-based affinity enrichment, high-resolution liquid chromatography mass spectrometry analysis, and integrated bioinformatics analysis were used to characterize the lysine succinylome (K-suc) and acetylome (K-ace) of rice leaves. In total, 2,593 succinylated and 1,024 acetylated proteins were identified, of which 723 were simultaneously acetylated and succinylated. Proteins involved in photosynthetic carbon metabolism such as the large and small subunits of RuBisCO, ribosomal functions, and other key processes were subject to both PTMs. Preliminary insights into oxidant-induced changes to the rice acetylome and succinylome were gained from treatments with hydrogen peroxide. Exposure to oxidative stress did not regulate global changes in the rice acetylome or succinylome but rather led to modifications on a specific subset of the identified sites. De-succinylation of recombinant catalase (CATA) and glutathione S-transferase (OsGSTU6) altered the activities of these enzymes showing that this PTM may have a regulatory function. These findings not only greatly extend the list of acetylated and/or succinylated proteins but they also demonstrate the close cooperation between these PTMs in leaf proteins with key metabolic functions. Protein post-translational modifications such as lysine succinylation and acetylation regulates protein functions in response to metabolic and environmental cues. Here, we provide the first evidence that many proteins in rice leaves involved in photosynthesis, primary and redox metabolism, and also ribosomal functions are acetylated and succinylated simultaneously. Crucially, exposure to oxidative stress altered these post-translational modifications on a specific subset of the identified sites. Succinylation altered the activities of catalase and a glutathione s-transferase. Hence, lysine succinylation and acetylation regulate the activities of proteins involved in plant responses to oxidative stress.