TMT-MS/MSproteomic analysis of the carbohydrate-active enzymes in the fruiting body ofPleurotus tuoliensisduring storage

BACKGROUND The fruiting body ofPleurotus tuoliensisdeteriorates rapidly after harvest, causing a decline in its commercial value and a great reduction in its shelf life. According to the present research, carbohydrate-active enzymes (CAZymes) may cause the softening, liquefaction and autolysis of mature mushrooms after harvest. To further understand thein vivomolecular mechanism of CAZymes affecting the postharvest quality ofP. tuoliensisfruiting bodies, a tandem mass tags labelling combined liquid chromatography-tandem mass spectrometry (TMT-MS/MS) proteomic analysis was performed onP. tuoliensisfruiting bodies during storage at 25 degrees C. RESULTS A total of 4737 proteins were identified, which had at least one unique peptide and had a confidence level above 95%. Consequently, 1307 differentially expressed proteins (DEPs) were recruited using the criteria of abundance fold change (FC) >1.5 or < 0.67 andP < 0.05. The identified proteins were annotated by dbCAN2, a meta server for automated CAZymes annotation. Subsequently, 222 CAZymes were obtained. Several CAZymes participating in the cell wall degradation process, including beta-glucosidase, glucan 1,3-beta-glucosidase, endo-1,3(4)-beta-glucanase and chitinases, were significantly upregulated during storage. The protein expression level of CAZymes, such as xylanase, amylase and glucoamylase, were upregulated significantly, which may participate in theP. tuoliensispolysaccharide degradation. CONCLUSIONS The identified CAZymes degraded the polysaccharides and lignin, destroying the cell wall structure, preventing cell wall remodeling, causing a loss of nutrients and the browning phenomenon, accelerating the deterioration ofP. tuoliensisfruiting body. (c) 2020 Society of Chemical Industry

Automated summary

The study showed that certain carbohydrate-active enzymes (CAZymes) participate in the degradation of cell wall components during the storage of Pleurotus tuoliensis fruiting bodies, with some enzymes significantly upregulated which may accelerate the deterioration process.