Molecular Organization of the Saccharomyces cerevisiae Cell Wall 

Renata Vuković, Marijana Hudina-Domladovec* and V. Mrša

Laboratory of Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 41000 Zagreb, Croatia.
*Present address: Pliva d.d., Research Institute, Baruna Filipovića 89, 41000 Zagreb, Croatia

Article history:
Received June 20, 1994
Accepted September 26, 1994

Summary:
Saccharomyces cerevisiae cell wall is composed of a glucan network in which different mannoproteins are interspersed. 2-3 % of the wall consists of chitin which plays a role in cell septalion during the budding process. Interactions among wall components and the organization of these components in the cell wall are to a great extent unexplained. Recently, it has been observed that most proteins interact in vitro with glucan by hydrogen bonding at acidic pH in a rather nonspecific manner. Similar experiments have, therefore, beat performed wiith other cell wall components and it has been found that proteins interact with chitin in a similar fashion, although not as strongly as wiith glucan. Glucan-glucan and glucan-chitin interactions have also been observed, but no binding of either proteins, glucan, or chitin to mannan chains of mannoproteins have been detected. Cell walls of intact cells bind proteins added to the yeast suspension very poorly. Similar results have also been obtained with isolated cell walls which still retained the shape of the cell. If cells are broken in a mechanical homogenizer at acidic pH, released intracellular proteins bind to the inner side of the wall efficiently. Results suggest a layered structure of the S. cerevisiae cell wall with mannan chains forming the outer, and glucan building the inner layer.