Binding of purified and radioiodinated capsular polysaccharides from Cryptococcus neoformans serotype A strains to capsule-free mutants

Journal Article · Mon Dec 01 00:00:00 EST 1986 · Infect. Immun.; (United States)

OSTI ID:6778347

Small, J M; Mitchell, T G

Strains 6, 15, 98, 110, and 145 of Cryptococcus neoformans serotype A vary in capsule size, animal virulence, and susceptibility to in vitro phagocytosis. The isolated capsular polysaccharides (CPSs) differ in monosaccharide composition ratios and molecular size, as determined by gel filtration. The purpose of this investigation was to characterize the binding of CPSs to capsule-free mutants of C. neoformans and to examine CPSs from these strains for differences in their ability to bind, to determine whether such differences might explain the variation in the pathobiology of these strains. CPSs were partially periodate oxidized, tyraminated, iodinated with /sup 125/I, and used in binding studies with two capsule-free mutants of C. neoformans, strain 602 and Cap59. Binding was specific for yeast species and for polysaccharide and was saturable, which is consistent with a receptor-mediated mechanism of attachment. Binding occurred rapidly and was only slowly reversible. Binding was also independent of pH from pH 5.5 to 8, of cation concentrations, and of competition by sugars up to 1.0 M concentrations. Only a portion of CPS was capable of binding, and strains varied in the extent to which their CPS bound. CPS-15-IV (peak IV was the major polysaccharide peak on DEAE-cellulose chromatography of CPS from strain 15) had the highest proportion of binding (40%), followed by CPS from strains 98, 6, 145, 110, and 15-III (peak III was an earlier eluting fraction of CPS from strain 15). The CPSs differed similarly in their ability to competitively inhibit binding. Treatment of CPS, but not yeast cells, with proteinase XIV abolished binding without altering the CPS gross structure. Treatment of yeast cells with proteases, heat, or formaldehyde did not alter binding, and both strain 602 and Cap59 bound CPS similarly. Binding to encapsulated yeast cells was minimal.

• Research Organization: Duke Univ. Medical Center, Durham, NC
• OSTI ID: 6778347
• Journal Information: Infect. Immun.; (United States), Vol. 3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
POLYSACCHARIDES
RECEPTORS
YEASTS
RADIORECEPTOR ASSAY
CHEMICAL BONDS
MONOSACCHARIDES
MUTANTS
PEPTIDE HYDROLASES
TYRAMINE
AMINES
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARBOHYDRATES
DRUGS
ENZYMES
FUNGI
HYDROLASES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
MEMBRANE PROTEINS
MICROORGANISMS
ORGANIC COMPOUNDS
PHENOLS
PLANTS
PROTEINS
SACCHARIDES
SYMPATHOMIMETICS
TRACER TECHNIQUES
550701* - Microbiology- Tracer Techniques