Analysis of mannans of two relatively avirulent mutant strains of Candida albicans
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A Saxena1, C F Hammer, R L Cihlar
1Department of Microbiology, School of Medicine, Georgetown University, Washington, D.C. 20007.
Abstract:
We previously reported the isolation of two cerulenin-resistant mutant strains of Candida albicans 4918 that differ in adherence properties and are less virulent than the parental strain. In addition, biochemical characterization demonstrated significant differences in both protein and polysaccharide composition of cell wall material between the mutant and wild-type strains. These observations prompted studies concerning the chemical structure of mannans in these strains. After extraction and subsequent purification by ion-exchange chromatography, mannan fractions were subjected to either mild acid hydrolysis, alkali hydrolysis, or acetylation followed by acetolysis. Acid- and alkali-modified mannans were studied by proton magnetic resonance spectroscopy, and released products were analyzed by high-performance liquid chromatography on an Aminex HPX-42A column. The results demonstrated quantitative and qualitative differences between mannooligosaccharides of the wild-type and mutant strains in the identity of released oligosaccharides as well as in linkage of the oligosaccharides to the protein backbone.
Insights
Cerulenin-resistant Candida albicans mutants show altered cell wall mannan structures. These differences in mannan composition and linkage impact oligosaccharide identity and protein backbone attachment.
Area of Science:
- Mycology
- Biochemistry
- Carbohydrate Chemistry
Background:
- Two cerulenin-resistant Candida albicans mutant strains were previously isolated.
- These mutants exhibit altered adherence properties and reduced virulence compared to the wild-type strain.
- Significant differences in cell wall protein and polysaccharide composition were noted between mutant and wild-type strains.
Purpose of the Study:
- To investigate the chemical structure of mannans in cerulenin-resistant Candida albicans mutants.
- To compare the mannan composition and structure between mutant and wild-type strains.
- To elucidate potential structure-function relationships in Candida albicans cell walls.
Main Methods:
- Mannan extraction and purification using ion-exchange chromatography.
- Chemical modification of mannans via mild acid hydrolysis, alkali hydrolysis, or acetylation followed by acetolysis.
- Structural analysis using proton magnetic resonance spectroscopy and high-performance liquid chromatography (HPLC) on an Aminex HPX-42A column.
Main Results:
- Quantitative and qualitative differences were observed in the mannooligosaccharides of wild-type and mutant strains.
- Variations were identified in the identity of released oligosaccharides.
- Differences in the linkage of oligosaccharides to the protein backbone were detected.
Conclusions:
- The chemical structure of mannans in cerulenin-resistant Candida albicans mutants differs significantly from the wild-type strain.
- These structural variations in mannans may contribute to the observed differences in adherence and virulence.
- Further research into Candida albicans cell wall mannan structure is warranted to understand its role in fungal biology.