Chemical Fractionation of the Cell Walls of Mycelial and Yeast-like forms of Mucor rouxii: A Comparative Study of the Polysaccharide and Glycoprotein Components

Abstract

Walls of the mycelial (M) and yeast-like (Y) forms of Mucor rouxii were prepared with the carbohydrate labelled with 14C and the peptide and polypeptide labelled with SH. Walls were extracted by sequential treatment with EDTA, NaOH and acetic acid. The polymers released were separated by glass-fibre paper electrophoresis and gel filtration which showed the presence, in both M and Y walls, of high molecular weight strongly acidic polysaccharides, high molecular weight weakly acidic glycoproteins and low molecular weight glycopeptides, which are weakly acidic or neutral. The strongly acidic polysaccharides from both M and Y forms contained D-glucuronic acid, D-mannose, D-galactose and L-fucose ; the glycoproteins and glycopeptides from both forms had D-mannose as the major sugar. Y walls gave in addition a weakly acidic polysaccharide containing D-glucuronic acid and D-mannose. The strongly acidic polysaccharides of the M form contained a greater proportion of D-galactose and L-fucose than did corresponding polymers of the Y form. The differences in composition of these polymers are discussed in terms of the possible differences in their structure and the relationship to morphology.

Formation of lipid-linked sugars in mycelial and yeast-like forms ofMucor rouxii

“…Mannoproteins and mannose containing polysaccharides are the major cell wall components of yeast-like and mycelial forms of Mucor rouxii (18). This is consistent with the evidences presented in this paper which show that dolichol-P-mannose is synthesized from GDP-mannose and endogenous or exogenous dolichol-P in cell wall fragments from both yeast-like and mycelial forms.…”

Studies ON MUCORALEAN MYCOPARASITES

“…Y-phase cell walls of other dimorphic mucorine fungi have been shown to have an enhanced uronic acid content (Dow and Rubery, 1977). If this also occurred in Mycotypha microspora, the resultant increased cation-binding capacity of its Y-phase cell walls might prevent passage of positively charged compounds through them.…”

Studies on Mucoralean Mycoparasites

“…This could be due to the physical confinement of tropism-inducing compounds within the host owing to biochemical changes in the cell wall associated with Y-phase growth, for instance, increased cation-binding capacity through increased glucuronic acid content. It may be relevant that Y-cells of Mucor rouxii contain more uronic acid than M-cells (Dow and Rubery, 1977).…”