Detection and structural characterization of natural Ara h 7, the third peanut allergen of the 2S albumin family.
In recent years, several novel relevant peanut allergens have been identified. Among those, a new member of the conglutin family was cloned by a phage display approach and initially annotated as Ara h 7.0101. Later, however, recloning of Ara h 7 revealed an alternate isoform, termed Ara h 7.0201. Because the natural Ara h 7 counterpart had not been found at the protein level in peanut extracts, the aim of the present study was to search for authentic natural Ara h 7 protein(s). To this end, enriched low molecular mass proteins (<20 kDa) from peanut extracts were separated by 2D electrophoresis and subjected to mass spectrometric analyses. Fifty of 65 analyzed spots were identified. Interestingly, Ara h 7.0101 was not identified, but Ara h 7.0201 and Ara h 7.0202, a different Ara h 7 isoallergen containing an additional pro-peptide cleavage site, were. In accordance with the conserved cysteine pattern of conglutins, Ara h 7.0201 possesses eight cysteine residues, in contrast to the six cysteines present in the previously cloned Ara h 7.0101. Moreover, a putative cleavage site in the Ara h 7.0202 isoform points to the characteristic biological function of conglutins as amylase/trypsin inhibitors.
Schmidt
Hendrik
H
Molecular Immunology, Institute for Immunology, Christian-Albrechts-University of Kiel, Building 17, Arnold-Heller-Strasse 3, D-24105 Kiel, Germany.
Krause
Susanne
S
Gelhaus
Christoph
C
Petersen
Arnd
A
Janssen
Ottmar
O
Becker
Wolf-Meinhard
WM
D055516:2S Albumins, Plant / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D052179:Antigens, Plant / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010367:Arachis; D001483:Base Sequence; D015180:Electrophoresis, Gel, Two-Dimensional; D008969:Molecular Sequence Data; D010936:Plant Extracts / Q000737:chemistry*; D020033:Protein Isoforms / Q000737:chemistry; D020543:Proteome / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
D055516:2S Albumins, Plant; D052179:Antigens, Plant; D010936:Plant Extracts; D020033:Protein Isoforms; D020543:Proteome