Global Profiling of Lysine Succinylation Reveals the Regulation of Carbon Fixation and Oil Production in <i>Nannochloropsis oceanica</i>

Lysine succinylation (Ksu) is a key post-translational modification known to regulate protein function, yet its role in microalgae remains unclear. Here, we profiled the global Ksu landscape in <i>Nannochloropsis</i> to explore its involvement in carbon fixation and lipid production. Using LC-MS/MS, 1303 Ksu sites were identified across 3729 proteins. These modified proteins are mainly localized in the chloroplast, cytoplasm, and mitochondria. Motif analysis revealed conserved amino acid patterns unique to Ksu, distinguishing it from other modifications. Functional enrichment indicated Ksu's involvement in glycolysis, the TCA cycle, carbon fixation, and lipid metabolism, highlighting its regulatory role in energy balance and biosynthesis. Transcriptomic integration under nutrient stress suggested that Ksu may also contribute to abiotic stress responses. This study provides the first comprehensive view of the succinylome in <i>Nannochloropsis</i>, offering insights into its metabolic regulation and laying a foundation for future biotechnological applications.