title: Identification and Characterization of Complex Glycosylated Peptides Presented by the MHC Class II Processing Pathway in Melanoma.
abstract: The MHC class II (MHCII) processing pathway presents peptides derived from exogenous or membrane-bound proteins to CD4+ T cells. Several studies have shown that glycopeptides are necessary to modulate CD4+ T cell recognition, though glycopeptide structures in these cases are generally unknown. Here, we present a total of 93 glycopeptides from three melanoma cell lines and one matched EBV-transformed line with most found only in the melanoma cell lines. The glycosylation we detected was diverse and comprised 17 different glycoforms. We then used molecular modeling to demonstrate that complex glycopeptides are capable of binding the MHC and may interact with complementarity determining regions. Finally, we present the first evidence of disulfide-bonded peptides presented by MHCII. This is the first large scale study to sequence glyco- and disulfide bonded MHCII peptides from the surface of cancer cells and could represent a novel avenue of tumor activation and/or immunoevasion.
authors.forename: Stacy A
authors.initials: SA
authors.lastname: Malaker
authors.affiliation: Department of Medicinal Chemistry, University of Florida , Gainesville, Florida 32610, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ferracane
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.
authors.forename: Florence R
authors.initials: FR
authors.lastname: Depontieu
authors.forename: Angela L
authors.initials: AL
authors.lastname: Zarling
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Shabanowitz
authors.forename: Dina L
authors.initials: DL
authors.lastname: Bai
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, United States.
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Topalian
authors.forename: Victor H
authors.initials: VH
authors.lastname: Engelhard
authors.forename: Donald F
authors.initials: DF
authors.lastname: Hunt
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002240:Carbohydrate Sequence; D045744:Cell Line, Tumor; D022801:Complementarity Determining Regions / Q000737:chemistry* / Q000276:immunology; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry / Q000276:immunology; D006020:Glycopeptides / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D006031:Glycosylation; D006684:HLA-DR Antigens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D006801:Humans; D008544:Melanocytes / Q000276:immunology* / Q000473:pathology; D008958:Models, Molecular; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D013816:Thermodynamics
chemical_list: D022801:Complementarity Determining Regions; D004220:Disulfides; D006020:Glycopeptides; D006684:HLA-DR Antigens
keywords: MHC class II; glycopeptide analysis; immunology; mass spectrometry