title: Characterization of mustard 2S albumin allergens by bottom-up, middle-down, and top-down proteomics: a consensus set of isoforms of Sin a 1.
abstract: The mustard allergen Sin a 1 belongs to the 2S-albumin family of seed-storage proteins. Because of its high abundance in mustard seeds and the potential to elicit severe allergenic reactions, Sin a 1 is considered to be a major allergen in mustard. Eight Sin a 1 isoforms have been identified using DNA cloning and sequencing, and we aim in this study to thoroughly investigate sequence heterogeneity using a novel combination of bottom-up, middle-down, and top-down proteomics. The characterization of purified Sin a 1 extract shows that sequence diversity is far more pronounced than previously assumed. We identified in total 24 sequence polymorphisms including 17 yet unpublished point mutations. Using middle-down and top-down approaches on the subunit and protein level of Sin a 1, we were able to detect eight consensus isoforms of Sin a 1(including four novel isoforms), which we detect in the majority of the four different mustard samples included in this study. In addition, we provide for the first time data on relative abundance of the main Sin a 1 isoforms and identify phytic acid as a potential ligand of Sin a 1. Together, these data can form the basis for a more detailed investigation of the effect of Sin a 1 polymorphic sites on allergenicity of isoforms.
authors: Department of Chemistry, Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster , Corrensstr. 45, 48149 Münster, Germany.
authors: Marlene
authors: M
authors: Hummel
authors: Tina
authors: T
authors: Wigger
authors: Jens
authors: J
authors: Brockmeyer
mesh_terms: D000485:Allergens / Q000737:chemistry*; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000276:immunology*; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000196:embryology / Q000276:immunology*; D010940:Plant Proteins / Q000276:immunology*; D020033:Protein Isoforms / Q000276:immunology*; D040901:Proteomics; D012639:Seeds / Q000276:immunology*; D017386:Sequence Homology, Amino Acid
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D010940:Plant Proteins; D020033:Protein Isoforms; C079479:Sin a I protein, Sinapis alba
keywords: LC−MS; Sin a 1; allergens; mass spectrometry; mustard; protein isoforms; protein modification