Influence of aeration and [ rho0]mutation on the structure of the cell walls of Saccharomyces cerevisiae and S. diastaticus

Abstract

The structure of the cell walls of Saccharomyces cerevisiae and S. diastaticus wild strains and mutants [rho0] was studied after growth of the cells in aerobiosis and without aeration. Transmission electron microscopy observations of the walls showed that in respiratory deficient cells the external region, corresponding to the phosphopeptidomannan layer, was altered, while the inner zone corresponding to the wall matrix was less damaged. Chemical analysis of the purified walls as well as of pronase extracted heteropolyosides revealed in the mutants [rho0] and in the cells grown without aeration, but to lesser extent, an enhanced synthesis of phosphopeptidomannans. These polymers were, however, less phosphorylated and their apparent molecular mass was lower than those of phosphopeptidomannans extracted from wild strains grown under aerobiosis. The chemical analysis of the wall and of wall residues provides results consistent with the transmission electron micrographs. It is suggested that in respiratory deficient cells, there is a lack of a mitochondrial function which controls the synthesis of the wall phosphopeptidomannans.