A seroreactive 120-kilodalton beta-1,3-glucanase of Coccidioides immitis which may participate in spherule morphogenesis

Abstract

A 13-glucosidase of Coccidioides immitis was identified in electrophoresis gel separations of the concanavalin Abound mycelial culture-filtrate-plus-lysate preparation. p-Nitrophenol-1-D-glucopyranoside was used as the substrate to visualize the enzymatically active fraction in nonreducing gels. The gel-isolated, chromatographically purified enzyme has an optimal pH of 8.0 and cleaves 0-1,3-glycosyl linkages. The alkaline 13-glucosidase was further characterized by a pI of 3.8 to 4.0, optimal activity at 37 to 40°C, and molecular size of 120 kDa as identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified 1-glucosidase is identical to a previously reported 120-kDa antigen (Ag) which reacts with immunoglobulin M (IgM) tube precipitin (TP) antibody in sera from patients with coccidioidomycosis. The TP-Ag was described as a valuable serodiagnostic reagent for detection of specific IgM in patients with early coccidioidal infections. The * Corresponding author. enzyme reacts with immunoglobulin M (IgM) precipitin antibody in sera from patients with coccidioidomycosis.

Electrophoretic karyotypes of clinical isolates of Coccidioides immitis

“…The probe was identified in this study as CnR. Three DNA probes from C. immitis were used and previously described as the 1.2-kb cDNA which encodes a 34-kDa chymotrypsinlike serine proteinase (12), the 0.2-kb cDNA which encodes a 7.3-kDa T-cell-reactive peptide (20), and a 0.8-kb cDNA isolated from a C. immitis cDNA expression library which was screened with rabbit antiserum raised against a purified 120-kDa alkaline ,-glucosidase (21). These three C. immitis cDNA probes were identified in this study as CiSP, CiTRP, and CiAG, respectively.…”

“…In this paper, we examine the karyotypes of 12 clinical isolates of C. immitis by contour-clamped homogeneous electric field (CHEF) gel electrophoresis (5). DNA probes derived from a conserved ribosomal gene fragment and three previously cloned C. immitis genes (12,20,21) were used in hybridization experiments to confirm the number of chromosomal bands and compare gene linkage patterns of the different isolates. Results of CHEF analyses were correlated with data obtained from cytofluorometric determinations of total nuclear DNA content, and together these techniques were used to estimate the genome size of C. immitis.…”

Histoplasma capsulatum Strain Variation in Both H Antigen Production and β-Glucosidase Activity and Overexpression of HAG1 from a Telomeric Linear Plasmid

“…Fungal ␤-glucosidases have been speculated to function in nutrient acquisition (by the metabolism of cellulose to acquire glucose) (17) or in cell wall remodeling events (by the breakdown of cell wall polymers and carbohydrates) (11). Relevant to the former model, Borok has speculated that the brown mycelial phenotype may be associated with growth on complex carbohydrate media requiring microbial substrate hydrolysis to β-glucosidase activity (mU/ml) obtain simple sugars, while the albino mycelial phenotype is favored when glucose is provided (1).…”

“…The heavily sporulating brown phenotype and the more vegetative albino phenotype apply to mycelial cultures and not directly to the yeast morphotype that we have used, but it should be noted that both of our high-expression RFLP class II strains (G217B and G222B) are derived from brown mycelial isolates. With regard to the cell wall remodeling hypothesis, Kruse and Cole have demonstrated blocking of arthroconidium-to-spherule-phase transition in the fungal pathogen Coccidioides immitis by inhibition of ␤-glucosidase activity, suggesting a role for this enzyme in the hydrolysis of fungal cell walls (11). Definitive assignment of a biological role for the H antigen and determination of any effect on virulence will require targeted gene disruption and subsequent complementation to fulfill Koch's molecular postulates.…”

History of medical mycology in the united states.

“…In 1992, Cole et al also reported isolation and expression of the gene that encoded the enzyme (63). In the same year, Kruse and Cole isolated and characterized another enzyme, ␣-glucosidase, which was identical to the 120-kDa tube precipitin (TP) antibody-reactive mycelial fraction of C. immitis (227). This enzyme was expressed by both forms of the fungus.…”