Qualitative lysine crotonylome analysis in the ovarian tissue of Harmonia axyridis (Pallas)

Lysine crotonylation (Kcr) is a newly discovered posttranslational modification (PTM), which has been studied at the proteomics level in a few species, with the study of Kcr in female fertility and in insect species is still lacking. Harmonia axyridis (Pallas) is a well-known beneficial insect used as a natural biological control agent against aphids in agriculture. Here, global Kcr identification in ovarian tissue of H. axyridis at diapause stage was performed to reveal potential roles for Kcr in H. axyridis ovarian cellular processes, female fertility and diapause regulation. In total, 3084 Kcr sites in 920 proteins were identified. Bioinformatic analyses revealed the distribution of these proteins in multiple subcellular localization categories and their involvement in diverse biological processes and metabolism pathways. Carbohydrate and energy metabolism related cellular processes including citric acid cycle, glycolysis and oxidative phosphorylation appeared be affected by Kcr modification. In addition, regulation of translation and protein biosynthesis may reflect Kcr involvement in diapause in H. axyridis, with Kcr affecting ribosome activities and amino acid metabolism. Moreover, Kcr modulation H. axyridis ovary development regulation may share some common mechanism with Kcr participation in some disease progression. These processes and pathways were uncovered under diapause stage, but possibly not enriched/specific for diapause stage due to limitations of qualitative proteomics experimental design. Our results informs on the potential for Kcr modifications to regulate female fertility and insect physiology.