Mass Spectrometric Analysis of N-Glycome of Patatin Proteins from Three Potato Cultivars

As a vital post-translational modification of potato tuber proteins, N-glycosylation directly regulates protein structural stability, biological activity and processing properties. N-glycome profiles of tuber storage proteins exhibit cultivar-specific characteristics, but the differential glycosylation across potato germplasms has not been fully elucidated. In this work, the major tuber patatin glycoprotein was purified from three potato cultivars as research material to investigate their N-glycosylation features and inter-cultivar variations. N-glycans were released via nonreductive chemical cleavage and derivatized with PMP, followed by qualitative and quantitative profiling using liquid chromatography-tandem mass spectrometry (LC-UV-MS/MS). In total, 11, 6 and 3 distinct N-glycan structures were identified from the three tested cultivars. Two novel glycan structures, Man₃XylGlcNAc₂ and Man₄XylGlcNAc₂, were identified in this study. The relative abundances of Man₃XylFucGlcNAc₂ and Man₃XylGlcNAc₂ exhibited highly significant inter-cultivar differences (p < 0.01). Notably, patatin carried unique N-glycans modified with exclusive α1,3-fucosylation, and overall glycan composition and relative abundance varied markedly across the three cultivars. This study systematically elucidates the effects of potato cultivar germplasm on patatin N-glycosylation and analyzes the unique glycosylation signatures of patatin from the three varieties. The obtained glycomic dataset provides fundamental theoretical support for germplasm screening, functional modification of potato storage proteins, and the optimization of potato deep-processing.