Dataset Information

Precision mapping of the human O-GalNAc glycoproteome through SimpleCell technology.

ABSTRACT: Glycosylation is the most abundant and diverse posttranslational modification of proteins. While several types of glycosylation can be predicted by the protein sequence context, and substantial knowledge of these glycoproteomes is available, our knowledge of the GalNAc-type O-glycosylation is highly limited. This type of glycosylation is unique in being regulated by 20 polypeptide GalNAc-transferases attaching the initiating GalNAc monosaccharides to Ser and Thr (and likely some Tyr) residues. We have developed a genetic engineering approach using human cell lines to simplify O-glycosylation (SimpleCells) that enables proteome-wide discovery of O-glycan sites using 'bottom-up' ETD-based mass spectrometric analysis. We implemented this on 12 human cell lines from different organs, and present a first map of the human O-glycoproteome with almost 3000 glycosites in over 600 O-glycoproteins as well as an improved NetOGlyc4.0 model for prediction of O-glycosylation. The finding of unique subsets of O-glycoproteins in each cell line provides evidence that the O-glycoproteome is differentially regulated and dynamic. The greatly expanded view of the O-glycoproteome should facilitate the exploration of how site-specific O-glycosylation regulates protein function.

SUBMITTER: Steentoft C

PROVIDER: S-EPMC3655468 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Precision mapping of the human O-GalNAc glycoproteome through SimpleCell technology.

Steentoft Catharina C Vakhrushev Sergey Y SY Joshi Hiren J HJ Kong Yun Y Vester-Christensen Malene B MB Schjoldager Katrine T-B G KT Lavrsen Kirstine K Dabelsteen Sally S Pedersen Nis B NB Marcos-Silva Lara L Gupta Ramneek R Bennett Eric Paul EP Mandel Ulla U Brunak Søren S Wandall Hans H HH Levery Steven B SB Clausen Henrik H

The EMBO journal 20130412 10

Glycosylation is the most abundant and diverse posttranslational modification of proteins. While several types of glycosylation can be predicted by the protein sequence context, and substantial knowledge of these glycoproteomes is available, our knowledge of the GalNAc-type O-glycosylation is highly limited. This type of glycosylation is unique in being regulated by 20 polypeptide GalNAc-transferases attaching the initiating GalNAc monosaccharides to Ser and Thr (and likely some Tyr) residues. W ...[more]

PMID: 23584533

Similar Datasets

Project description:Characterizing protein GalNAc-type O-glycosylation has long been a major challenge, and as a result, our understanding of this glycoproteome is particularly poor. Recently, we presented a novel strategy for high throughput identification of O-GalNAc glycosites using zinc finger nuclease gene-engineered "SimpleCell" lines producing homogeneous truncated O-glycosylation. Total lysates of cells were trypsinized and subjected to lectin affinity chromatography enrichment, followed by identification of GalNAc O-glycopeptides by nLC-MS/MS, with electron transfer dissociation employed to specify sites of O-glycosylation. Here, we demonstrate a substantial improvement in the SimpleCell strategy by including an additional stage of lectin affinity chromatography on secreted glycoproteins from culture media (secretome) and by incorporating pre-fractionation of affinity-enriched glycopeptides via IEF before nLC-MS/MS. We applied these improvements to three human SimpleCells studied previously, and each yielded a substantial increase in the number of O-glycoproteins and O-glycosites identified. We found that analysis of the secretome was an important independent factor for increasing identifications, suggesting that further substantial improvements can also be sought through analysis of subcellular organelle fractions. In addition, we uncovered a substantial nonoverlapping set of O-glycoproteins and O-glycosites using an alternative protease digestion (chymotrypsin). In total, the improvements led to identification of 259 glycoproteins, of which 152 (59%) were novel compared with our previous strategy using the same three cell lines. With respect to individual glycosites, we identified a total of 856 sites, of which 508 (59%) were novel compared with our previous strategy; this includes four new identifications of O-GalNAc attached to tyrosine. Furthermore, we uncovered ≈ 220 O-glycosites wherein the peptides were clearly identified, but the glycosites could not be unambiguously assigned to specific positions. The improved strategy should greatly facilitate high throughput characterization of the human GalNAc-type O-glycoproteome as well as be applicable to analysis of other O-glycoproteomes.

Project description:A large family of GalNAc transferases (GalNAc-Ts) catalyzes the covalent attachment of N-Acetylgalactosamine (GalNAc) to serine and threonine residues on proteins that pass through the secretory pathway in the first committed step of mucin-type O-glycosylation. Abnormalities in the activity of individual GalNAc-Ts can result in congenital disorders of O-glycosylation (CDG) and influence other biological functions. Although ~85% of proteins that pass through the secretory pathway are modified with O-glycans, only 47 O-glycosylation sites (O-glycosites) from 22 mouse glycoproteins and 17 publications are present on UniProt and an O-glycoprotein database (http://www.oglyp.org/). A compilation of all in vivo O-glycosites (the O-glycoproteome) would be an invaluable step in determining the function of proteins decorated with N-Acetylgalactosamine and what role(s), if any, the O-glycans play. While approaches to delineate O-glycosites have been developed for simple, genetically engineered cell lines, there is no universal approach to mapping the O-glycosites of glycoproteins in complex tissue extracts or biological fluids. We have developed chemical and enzymatic conditions that cleave solitary O-glycans while leaving the modified core protein/peptides assayable by mass spectrometry (MS). The methodology permits the mapping of thousands of O-glycosites decorated with Tn or T antigen from tissues or biological fluids. We then integrated an HCD-pd-EThcD MS workflow and software, including MSFragger-Glyco, pGlyco3, and O-Pair, to study the mouse brain, heart, lung, liver, spleen, kidney, colon, muscle, submandibular gland, and whole blood. The integrated approach identified 2154 solitary O-glycosites from 595 glycoproteins. The O-glycosites and glycoproteins displayed consensus motifs and Gene Ontology (GO) terms for O-glycoproteins. Limited overlap of O-glycosites was observed with protein O-GlcNAcylation and phosphorylation sites. Integrating quantitative glycoproteomics and proteomics revealed a tissue-specific regulation of O-glycosites that the differential expression of Galnt isoenzymes in tissues partly contributes to. We next used established quantitative glycoproteomics and proteomics methods to identify site-specific substrates that may contribute to biologically relevant phenotypes when Galnt2 was genetically ablated in a Galnt2-null mouse model, which presents with lipid and metabolic dysregulation. Our findings suggest networks of Galnt2 direct and indirect interactions that may explain the complex metabolic phenotypes. The mouse O-glycoproteome-map and quantitative glycoproteomics/proteomics approach will provide a valuable foundation for revealing the significance of O-glycosylation biology in CDGs and other diseases and conditions.

Dataset Information

Precision mapping of the human O-GalNAc glycoproteome through SimpleCell technology.

Publications

Precision mapping of the human O-GalNAc glycoproteome through SimpleCell technology.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets