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Muramidase-mediated damage to Candida yeast cells. Histochemical and immunochemical characterization of accumulating
G Marquis1, S Garzon, H Strykowski
1Department of Microbiology and Immunology, University of Montreal, Quebec, Canada.
Abstract:
Hen egg-white lysozyme is known to be fungicidal to blastoconidia of Candida albicans under defined in vitro conditions. This lethal action leads to changes in the layering of cell wall and to plasmolysis, caused by unremitting accumulation of wall-like material between the yeast cell wall and cytoplasmic membrane. Here, several methods were applied on ultrathin sections to define the nature of wall-like material: histochemical staining with periodic acid-thiocarbohydrazide-silver proteinate, periodic acid-alkaline bismuth, and phosphotungstic acid at low pH; the localization of the carbohydrate residues with lectin-gold complex; immunocytochemical staining with monospecific antibodies, factor 1 and 6, which recognized major cell wall antigens. The wall-like material was almost uniformly highlighted with periodic acid-thiocarbohydrazide-silver proteinate, factor 1 antibody, concanavalin A-gold and wheat germ agglutinin-ovomucoid-gold, indicating the presence of mannoproteins and chitin. The serotype A-specific epitope recognized by factor 6 antibody was not detected in the wall-like material, although it was demonstrated in the outer cell wall layers after 2 h of exposure to lysozyme.
Insights
Hen egg-white lysozyme damages Candida albicans cell walls, causing plasmolysis. This damage involves the accumulation of mannoproteins and chitin, but not serotype A-specific epitopes.
Area of Science:
- Mycology
- Biochemistry
- Cell Biology
Background:
- Hen egg-white lysozyme exhibits fungicidal activity against Candida albicans blastoconidia in vitro.
- Lysozyme-induced cell death involves cell wall alterations and plasmolysis due to material accumulation between the cell wall and cytoplasmic membrane.
Purpose of the Study:
- To elucidate the composition of the wall-like material accumulating in Candida albicans cells treated with hen egg-white lysozyme.
- To investigate the localization of specific cell wall components in response to lysozyme exposure.
Main Methods:
- Ultrathin sectioning of Candida albicans blastoconidia.
- Histochemical staining (periodic acid-thiocarbohydrazide-silver proteinate, periodic acid-alkaline bismuth, phosphotungstic acid).
- Lectins conjugated to gold particles (concanavalin A-gold, wheat germ agglutinin-ovomucoid-gold).
- Immunocytochemical staining with monospecific antibodies (factor 1 and factor 6).
Main Results:
- The accumulating wall-like material was consistently stained by periodic acid-thiocarbohydrazide-silver proteinate, concanavalin A-gold, wheat germ agglutinin-ovomucoid-gold, and factor 1 antibody.
- These results indicate the presence of mannoproteins and chitin within the wall-like material.
- Serotype A-specific epitopes, recognized by factor 6 antibody, were absent in the accumulated material but present in the outer cell wall after lysozyme exposure.
Conclusions:
- The wall-like material formed during lysozyme-induced cell death in Candida albicans is primarily composed of mannoproteins and chitin.
- Lysozyme treatment affects the cell wall structure, leading to the deposition of specific polysaccharides and proteins.
- The absence of serotype A-specific epitopes in the deposited material suggests differential incorporation of cell wall components.