Abstract
Lysine crotonylation of histone proteins is a recently-identified post-translational modification with multiple cellular functions. However, no information about lysine crotonylation of non-histone proteins in fruit cells is available. Using high-resolution LC-MS/MS coupled with highly sensitive immune-affinity antibody analysis, a global crotonylation proteome analysis of papaya fruit (Carica papaya L.) was performed. In total, 2,120 proteins with 5,995 lysine crotonylation sites were discovered, among which eight conserved motifs were identified. Bioinformatic analysis linked crotonylated proteins to multiple metabolic pathways, including biosynthesis of antibiotics, carbon metabolism, biosynthesis of amino acids, and glycolysis. particularly, 40 crotonylated enzymes involved in various pathways of amino acid metabolism were identified, suggesting a potential conserved function for crotonylation in the regulation of amino acid metabolism. Numerous crotonylation sites were identified in proteins involved in the hormone signaling and cell wall-related pathways. Our comprehensive crotonylation proteome indicated diverse functions for lysine crotonylation in papaya.