Global lysine crotonylome profiling of Nannochloropsis oceanica reveals extensive modification of proteins involved in carbon fixation and lipid metabolism

Lysine crotonylation (Kcr) is a recently identified post-translational modification (PTM) first characterized in mammals. A global crotonylome analysis was undertaken in microalga Nannochloropsis oceanica using high accuracy nano-LC-MS/MS in combination with crotonylated peptide enrichment. We systematically profiled Kcr in Nannochloropsis using LC-MS, identifying 5859 modification sites across 2044 proteins. Kcr-modified proteins were predominantly predicted to localize to the chloroplast, cytoplasm, and mitochondria, revealing a broad subcellular distribution. Motif analysis revealed conserved amino acid patterns distinguishing Kcr from other PTMs. Functional enrichment analysis showed that Kcr-modified proteins were significantly represented in pathways including glycolysis, the TCA cycle, carbon fixation, and lipid metabolism. Additionally, histone Kcr was also detected, providing a basis for future investigation of its possible epigenetic significance. These findings establish a global Kcr landscape in N. oceanica and provide a resource for future studies investigating the functional significance of crotonylation in carbon and lipid metabolism.