title: Isolation, expression and characterization of a minor allergen from Penicillium crustosum.
abstract: A ribosomal P1 protein, Pen b 26 from Penicillium brevicompactum, was previously identified as a major allergen. A homolog protein was isolated and characterized from Penicillium crustosum which is not known to be allergenic mold. A cDNA library of P. crustosum was constructed and screened using a probe based on the DNA sequence of Pen b 26. A positive clone was isolated, expressed in Escherichia coli, purified and characterized by comparing its immunological and physical properties to Pen b 26. It was designated as Pen cr 26 and had a 321 nt ORF corresponding to 107 amino acids with a MW of 11 kDa. Pen cr 26 had strong sequence homology to Pen b 26 (92% for nucleotides and 86% for amino acids) and its physical and predicted structural properties were similar to the latter. The level of expression of Pen cr 26 was much lower than that of Pen b 26 in the same expression vector. Both proteins were recognized equally well by the IgG class specific antibodies, but Pen cr 26 was poorly recognized by Penicillium-sensitive atopic sera (IgE), suggesting striking antigenic difference in IgE epitopes, i.e., 87% were positive for Pen b 26 while only 23% were positive for Pen cr 26. The allergenicity of Pen cr 26 seems to be minor in nature and it could be a hypoallergenic variant of Pen b 26.
authors.affiliation: Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada.
authors.forename: M Serdal
authors.initials: MS
authors.lastname: Sevinc
authors.forename: Veena
authors.initials: V
authors.lastname: Kumar
authors.forename: Makonnen
authors.initials: M
authors.lastname: Abebe
authors.forename: Michèle
authors.initials: M
authors.lastname: Lemieux
authors.forename: Hari M
authors.initials: HM
authors.lastname: Vijay
mesh_terms: D000485:Allergens / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010407:Penicillium / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000485:Allergens; D005656:Fungal Proteins
keywords: IgE immunoblot; cDNA cloning; fungal allergens; hypoallergen; ribosomal P1 proteins