Isolation and characterization of a cDNA clone encoding one IgE-binding fragment of Penicillium brevicompactum

Abstract

Rationale The abundance of allergenic Penicillium species has been associated with an increased incidence of childhood asthma and pulmonary bleeding. Penicillium brevicompactum has been identified as the most prevalent indoor Penicillium species. However, detailed studies on allergen of the ubiquitous Penicillium species are still lacking. For the characterization of allergens of prevalent Penicillium species, molecular cloning of the allergen genes of P. brevicompactum was performed in the present study. Methods A cDNA library of P. brevicompactum was constructed in Uni-ZAP® XR vector using mRNA isolated from the organism. The cDNA library of P. brevicompactum was screened using pooled atopic sera. Results One positive clone encoding a polypeptide of 11.06 kDa, designated as Pb2 was isolated. This clone was found to be reactive only against the atopic sera. The mRNA sequence of the clone was deduced from the cDNA of 0.5 kb transcript and found to be a 321 nt encoding 107 amino acids. Analysis of the crude extracts of the phage clone by SDS-PAGE immunoblot confirmed its expected molecular size. BLAST analysis showed that clone Pb2 had strong homology to the 60S acidic ribosomal protein P1 family from different eukaryotic sources, including the Alt a 12 allergen of mould Alternaria alternata which is an important source of fungal aeroallergens. Conclusions The results obtained suggest that 60S acidic ribosomal protein P1 is an allergen of P. brevicompactum and clone Pb2 contains the cDNA of this allergen.