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The walls of both, yeast and mycelial cells of Candida albicans possess a species-specific antigen that is recognized by a monoclonal antibody (MAb 3H8). This antigen can be extracted in the form of a very high Mr complex, close or over 106 Da, by treatment, with β-1,3-glucanase, β mercaptoethanol or dithothreitol, or mild alkali, but not by saturated hydrogen fluoride (HF) in pyridine, suggesting that the complex is bound to wall β-1,3 glucans, and to proteins by disulfide bonds, but not to β-1,6 glucans. Through its sensitivity to trypsin and different deglycosylation procedures, it was concluded that the epitope is associated to a glycoprotein containing N-glycosidic, but not O-glycosidic mannan moieties. By means of electrophoresis in polycrylamide gradient gels, followed by mass spectrometric analysis, the epitope was pinpointed to a very high MW complex containing Agglutinin-Like Sequence (ALS) family proteins, and other cytoplasmic, membrane and secreted proteins. The components of this complex are bound by unknown covalent bonds. The material extracted with β mercaptoethanol or dilute alkali appeared under the electron microscope as large aggregates in the form of spheroidal and mostly web-like structures of large sizes. These, and additional data, suggest that this protein complex may constitute an important part of the basic glycoprotein structure of C. albicans. The possibility that similar complexes exist in the wall of other fungi is an attractive, although yet untested possibility.

PCR was used to amplify fragments corresponding to CHS genes from Ustilago maydis, utilizing as primers oligonucleotides devised according to the conserved regions of fungal CHS genes. The PCR product was employed as a probe to screen a genomic library of the fungus. Two different CHS genes (Umchs1 and Umchs2) were thus identified in the positive clones recovered. Their sequence revealed high similarity with the CHS genes previously cloned from other fungi, especially in their central region. Alignment with the deduced protein sequences of all CHS genes reported up to date showed the existence of seven conserved domains. Transcripts from both genes were detected in the yeast and mycelial forms. In general, the transcripts from the Umchs1 gene appeared to be present at a higher level than the transcripts from the Umchs2 gene; the transcripts from both genes appeared to be more abundant in the mycelial form. Gene replacement of either gene and analysis of the resulting phenotype demonstrated that they are non-essential. Nevertheless, growth, chitin synthase activity levels, and chitin content of mycelial cells induced by cultivation in acidic media were all reduced in chs1 and chs2 mutants. However, mating, virulence and dimorphic behaviour were unaffected. Overall, the results indicate that the CHS1 and CHS2 genes encode products with redundant functions in U. maydis.