Global lactylation is downregulated despite lactate accumulation: lactylome data and functional insights during ISKNV infection.

Infectious spleen and kidney necrosis virus (ISKNV) induces aerobic glycolysis, leading to lactate accumulation. Lysine lactylation is a novel post-translational modification that employs lactate as its substrate. However, its landscape and functions during ISKNV infection remain elusive. In this study, we explored lactylation modification and lactylome in Chinese perch brain (CPB) cells after ISKNV infection. Results showed that the total lactylation level was significantly downregulated at 60 h post-infection (hpi), even though lactate was upregulated. Lactylome analysis identified 527 differentially lactylated proteins (DLPs) at 60 hpi, corresponding to 233 up-regulated and 456 down-regulated sites. The two particularly preferred sequence motifs of upregulated and downregulated lactylation were L*Kla and K/G***Kla***P, respectively. Functional enrichment analysis demonstrated that the up-regulated lactylated proteins were significantly enriched in spliceosome, nucleocytoplasmic transport, ribosome, and glycolysis pathways. Down-regulated lactylated proteins were abundant in ferroptosis, Wnt signaling pathway and lysine degradation. Network analysis of lactylated proteins demonstrated that the lactylation of ALDH-mt-like Iso X1, VDAC2, VDAC2-like Iso X1, VDAC1, and DVL3-like were linked to glycolysis, ferroptosis, necroptosis, and Notch signaling pathway. The downregulation of VDAC2 lactylation and upregulation of VDAC1, ALDH2 induced by ISKNV were verified by Co-IP, which confirmed the reliability of the lactylome data. These results showed that protein lactylation played a functionally significant regulatory role in metabolism and immunity during ISKNV infection, offering novel mechanistic insights and promising targets for ISKNV.