Discovery of potential involvement of protein lactylation during the development of pork quality

Lactate, as a glycolytic metabolite, is well known to be strongly associated with the development of fresh meat quality, yet little progress has been made regarding its significance in postmortem biochemical regulation. Our research last year identified for the first time in livestock meat science that lactate-derived protein lysine lactylation could occur in postmortem muscle. Propulsively, the current work aimed to provide a further overview of protein lactylation during muscle to meat conversion based on immunohistofluorescence with modification-specific proteomics profiling. Results demonstrated that, compared with 1 h postmortem, protein lactylation levels at 24 h postmortem responsive to lactate accumulation were notably higher, while no significant change was noted for the level of E1A binding protein p300 (p300), identified as a lactyltransferase. Meanwhile, p300 and lactylated proteins were broadly localized in the nucleus, cell membrane, and cytoplasm of postmortem myocytes, especially presenting a remarkable enhancement of the cytoplasmic distribution at 24 h postmortem. More importantly, it was disclosed that energy metabolism and muscle contraction were the two most critical biochemical pathways mediated by lactylation modification during muscle to meat conversion. These emerging findings hold promise to contribute to a lactate-based postmortem biochemical theory for unraveling and controlling the development of meat quality, especially those quality-defective pork and poultry with typically high lactate levels.