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TMT-MS/MS proteomic analysis of the Carbohydrate-active enzymes (CAZymes) in the fruiting body of Pleurotus tuoliensis during storage.

BACKGROUND
The fruiting body of Pleurotus tuoliensis deteriorates 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 the harvest. To further understand in vivo molecular mechanism of CAZymes affecting the postharvest quality of P. tuoliensis fruiting bodies, a tandem mass tags labeling combined liquid chromatography-tandem mass spectrometry (TMT-MS/MS) proteomic analysis was performed on P. tuoliensis fruiting bodies during storage at 25 °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 and p < 0.05. The identified proteins were annotated by dbCAN2, a meta server for automated carbohydrate-active enzymes (CAZymes) annotation. Subsequently, 222 CAZymes were obtained. Several CAZymes participating in the cell wall degradation process including β-glucosidase, glucan 1,3-β-glucosidase, endo-1,3(4)-β-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 the P. tuoliensis polysaccharide 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 of P. tuoliensis fruiting body. This article is protected by copyright. All rights reserved.