Investigation of cell wall proteins of Camellia sinensis leaves by combining cell wall proteomics and N-glycoproteomics

Cell wall proteins (CWPs) probably play a vital role in fluoride accumulation/detoxification of C. sinensis leaves. However, there has been a lack in CWP identification and characterization up to now. This study is aimed to characterize cell wall proteome of C. sinensis leaves and to develop more CWPs related to stress response. Cell wall proteomics and N-glycoproteomics was employed to investigate CWPs. CWPs were extracted by sequential salt buffers, while N-glycoproteins were enriched by hydrophilic interaction chromatography method, and subsequently all proteins were subjected to UPLC-MS/MS analysis. A total of 501 CWPs and 195 CWPs were identified respectively by cell wall proteomics and N-glycoproteomics profiling with 118 CWPs in common. Among identified CWPs, proteins acting on cell wall polysaccharides, proteases and oxidoreductases represent the top three functional groups. This was the first large-scale investigation of CWPs in C. sinensis.