title: Cloning, expression, and pore-forming properties of mature and precursor forms of pleurotolysin, a sphingomyelin-specific two-component cytolysin from the edible mushroom Pleurotus ostreatus.
abstract: Pleurotolysin, a sphingomyelin-specific cytolysin consisting of A (17 kDa) and B (59 kDa) components from the basidiomycete Pleurotus ostreatus, assembles into a transmembrane pore complex. Here, we cloned complementary and genomic DNAs encoding pleurotolysin, and studied pore-forming properties of recombinant proteins. The genomic regions encoding pleurotolysin A and B contained two and eight introns, respectively, and putative promoter sequences. The complementary DNA (cDNA) for pleurotolysin A encoded 138 amino acid residues, and the predicted product was identical with natural pleurotolysin A, except for the presence of the first methionine. Recombinant pleurotolysin A lacking the first methionine was purified as a 17-kDa protein with sphingomyelin-binding activity. The cDNA for pleurotolysin B encoded a precursor consisting of 523 amino acid residues, of which N-terminal 48 amino acid residues were absent in natural pleurotolysin B. Mature and precursor forms of pleurotolysin B were expressed as insoluble 59- and 63-kDa proteins, respectively, which were unfolded with 8 M urea and refolded by 100-fold dilution with 10 mM Tris-HCl buffer, pH 8.5. Although neither recombinant pleurotolysin A nor B alone was hemolytically active at higher concentrations of up to 100 mg/ml, they cooperatively assembled into a membrane pore complex on human erythrocytes and lysed the cell as efficiently as the natural proteins at nanomolar concentrations. In contrast, the precursor of pleurotolysin B was much less hemolytically active than mature pleurotolysin B in the presence of pleurotolysin A.
authors.affiliation: Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: Nobuki
authors.initials: N
authors.lastname: Sakurai
authors.forename: Jun
authors.initials: J
authors.lastname: Kaneko
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kamio
authors.forename: Toshio
authors.initials: T
authors.lastname: Tomita
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020076:Pleurotus / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D005656:Fungal Proteins; D011994:Recombinant Proteins; D013109:Sphingomyelins