0000000000131533
AUTHOR
J. Ruiz-herrera
Separation of chitosomes and secretory vesicles from the ?slime? variant of Neurospora crassa
Cells from the “slime” variant of Neurospora crassa were broken in isotonic conditions by use of triethanolamine buffer plus EDTA. After removal of large membranous structures by low-speed centrifugation, chitosomes and secretory vesicles were separated by means of gel filtration, precipitation of membranous contaminants with Concanavalin A, and centrifugation in sucrose or glycerol gradients. Polypeptidic composition of fractions enriched in secretory vesicles or chitosomes was found to be distinct. By these criteria we concluded that chitosomes and secretory vesicles represent different populations of microvesicles. Both microvesicular populations appeared free of endoplasmic reticulum an…
Self-assembly properties of the proteinaceous coat secreted by the ?slime? variant of Neurospora crassa
The proteinaceous extracellular material (PEM) synthesized by the cells of the ‘slime” strain of Neurospora crassa (see Martinez et al. 1989) was solubilized by treatment with urea or guanidine. Removal of these chemicals by dialysis, caused reassembly of the solubilized proteins into material with the same microscopic appearance as the original PEM. Polypeptide patterns from both native and reassembled structures were identical. Dialysis-mediated reassembly of the solubilized proteins appeared to be dependent on both concentration of the soluble macromolecules and time. Gel chromatography of PEM solubilized with different agents revealed two discrete populations of complexes with molecular…
Analysis of the polypeptide composition of the cell walls of Neurospora crassa. Similarities with the proteinaceous material secreted by the slime variant
The polypeptide composition of cell walls from the wild-type strain of Neurospora crassa is compared with that of the proteinaceous extracellular coat (PEM) secreted by the slime strain of this fungus. Analyses included determination of the polypeptide pattern by polyacrylamide gel electrophoresis and blotting followed by staining with Concanavalin A and antibodies raised against the overall antigenic components present in either (whole cell walls or PEM) structure. A complex protein assortment was found associated to the walls of the wild type strain. The similarities observed between the polypeptide patterns of the cell walls and PEM, in addition to the immunological cross-reactivity exhi…
Biogenesis of the Fungal Cell Wall
Cell walls play essential roles in growth, development, and in interactions of fungi with the environment and with other cells. Besides its primary protective role in shielding the cell against osmotic, chemical, and biological harm, the wall is involved in many other functions including morphogenesis, and some activities that may be denominated as “social”, such as morphological responses, antigenic expression, adhesion, and cell-cell interaction (Peberdy 1990; Ruiz-Herrera 1992; Sentandreu et al. 1991). There are many data supporting the idea that temporal and spatial regulation of wall polymer synthesis and assembly are critical for the properties of the walls, which thus do not exclusiv…
Characterization of a proteinaceous extracellular coat synthesized by the ?slime? variant of Neurospora crassa
Cells of the “slime” strain of Neurospora crassa synthesize a coherent extracellular material which remains attached to the cell surface, but is released into the liquid medium by shaking. The material was purified and studied by different criteria. By electron microscopy it appears as long wavy sheets which strongly bind concanavalin A, but not wheat germ agglutinin, and maintain their integrity in the absence of structural polysaccharides. Analysis of the purified material revealed that it was free of contaminating membranes; it contained more than 70% protein, 1% neutral sugars (glucose, mannose, fucose and galactose), less than 2% lipids and ca. 4% not-characterized hexosaminelike compo…
Inhibition of the dimorphic transition of Candida albicans by the ornithine decarboxylase inhibitor 1,4-diaminobutanone: alterations in the glycoprotein composition of the cell wall
Hyphal development in Candida albicans was selectively blocked by the ornithine decarboxylase competitive inhibitor 1,4-diaminobutanone (DAB). Inhibition of hyphal development required DAB during both yeast inoculum growth and subsequent incubation at 37 degrees C to induce mycelial growth. This effect was not due to general growth inhibition since DAB did not inhibit yeast growth, and reduced protein synthesis by 30% at most. Moreover, protein synthesis was unaffected by DAB when cells were pre-grown in drug-containing media. Since DAB inhibited dimorphic transition at 37 degrees C, morphology- and temperature-dependent protein synthesis could be distinguished. DAB stimulated the synthesis…