ULTRASTRUCTURE OF THE CELL-WALL OF SCHIZOSACCHAROMYCES-POMBE FOLLOWING TREATMENT WITH VARIOUS GLUCANASES

The ultrastructure of isolated cell walls of Schizosaccharomyces pombe was studied by electron microscopy after treatment with the following purified enzymes: endo-beta-(1-->3)-glucanase, endo-beta-(1-->6)-gluc anase, and endo-alpha-(1-->3)-glucanase produced by Bacillus circulans ; exo-beta-(1-->3)-glucanase and endo-beta-(1-->3)-glucanase produced by Schizosaccharomyces japonicus var. versatilis. The exo-beta-(1-->3) -glucanase had no detectable effect on the walls, but amorphous wall m aterial was removed by action of the endo-beta-(1-->3) and endo-beta - (1-->6)-glucanases of B. circulans to reveal a wall component consisti ng of densely interwoven microfibrils. The fibrils were hydrolyzed by treatment with the Schiz. japonicus endo-beta-(1-->3)-glucanase follow ed by B. circulans endo-alpha-(1-->3)-glucanase-suggesting that they w ere composed of -beta-(1-->3)-linked glucan and alpha-(1-->3)-linked g lucan. The presence of a fibrillar component in untreated walls was ev ident after negative staining. (C) 1995 Academic Press, Inc.