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 ) and acetylome (K ) 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.

Future work should be directed to establish the structural bases of the specificity of MSH-dependent enzymes, thus facilitating drug developments. Antioxid. Redox Signal. 28, 487-504.

Background: Methionine sulfoxide post-translational modifications have an important new signaling role in cells. Results: Methionine sulfoxide reductase MsrA of the pathogenic actinomycete Corynebacterium diphtheriae (Cd-MsrA) uses a unique intramolecular redox relay mechanism coupled to mycothiol. Conclusion: For methionine sulfoxide control, Cd-MsrA is flexible in receiving electrons from both the thioredoxin and the mycothiol pathways. Significance: C. diphtheriae MsrA is a redox regulator for methionine sulfoxide signaling.