Global profiling of N-glycosylated proteins in the diatom Phaeodactylum tricornutum

ABSTRACT: N-glycosylation is an important posttranslational modification in all eukaryotes, but little is known about the N-glycoproteomes in microalgal systems. Here, N-glycoproteome of the model diatom Phaeodactylum tricornutum was unveiled. Totally, 893 different N-glycosylated sites from 649 proteins were identified from P. tricornutum. The new synthesized N-glycans were principally transferred to asparagine residues within the conserved N-X-S/T (where X is a residue other than proline) sequence of nascent polypeptide chains. Functional annotation of N-glycosylated proteins showed that 70% N-glycoproteins were involved in vesicular transport and posttranslational modification, protein turnover, chaperones, indicating the N-glycosylation was important for these functions. Of the all identified N-glycoproteins 45.3% were predicted to localize on chloroplast, which implied the widespread regulatory role of N-glycosylation in chloroplast. Furthermore, the enrichment results of N-glycoproteins indicated that compared to ‘Cellular component’ and ‘Biological process’ categories proteins related with the ‘Molecular function’ category were more prone to be N-glycosylated. And it was speculated that N-glycosylation played a vital regulatory role in catalytic activity of enzymes and metabolism processes of many small molecules. 47% of all enriched proteins were related with metabolic pathways. The functional annotation and enrichment of N-glycoproteins suggested that N-glycoproteins participated in a variety of important metabolic pathways and perform different functions in P. tricornutum. 12 proteins involved in the ER quality control mechanism and ER- associated degradation pathway were identified as N-glycosylated proteins, indicating that the N-glycosylated modification was important for their functions in the protein N-glycosylation pathway. Additionally, some interacted glycoproteins were classified from this study, which provided valuable information for studying the functions of these glycoproteins. In the study, the identification of N-glycosylation on nascent proteins expands our understanding of this PTM at a proteomics scale and may facilitate the elucidation of the precise function of proteins in this model diatom.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Phaeodactylum Tricornutum

SUBMITTER: Xiaojuan Liu  

LAB HEAD: Xiaojuan Liu

PROVIDER: PXD022483 | Pride | 2021-11-03

REPOSITORIES: Pride