engleski

Synergism of non-covalently linked proteins in building the Saccharomyces cerevisiae cell wall

Saccharomyces cerevisiae cell wall is composed of ß-glucans, mannoproteins and small amounts of chitin. Mannoproteins can either be non-covalently (Scw proteins - soluble cell wall proteins), or covalently bound to glucan. Their physiological role is mostly unknown. In order to assess possible role of Scw proteins mutant strains were constructed by disruption of SCW4, SCW10, SCW11, and BGL2 genes. Influence of these major Scw proteins on cell integrity and protein secretion into the growth medium was examined. scw4scw10, scw4scw10bgl2 and scw4scw10scw11bgl2 secret less proteins in comparison to wild type, single mutants and scw4scw10scw11. Sensitivity of cell wall to ß-1, 3-glucanase was examined and scw4scw10scw11 exhibited a significant increase in resistance. However, when the outer mannoprotein layer was removed by proteinase K all mutants showed wild type level of sensitivity indicating that observed effect is due to changes in the mannan layer. Viability of mutants in exponential and stationary phase of growth was monitored. In the exponential phase scw4scw10 showed increased fraction of dead cells (5%), while scw4scw10scw11 had less than 1% of dead cells. In the stationary phase the fraction of dead cells increased to 22% in scw4scw10 and to 17% in scw4scw10scw11. Number of dead cells was reduced to 0.5-3% in all strains in both growth phases when cells were grown in 1M sorbitol. Results indicate that Scw proteins are involved in building and modifying the cell wall and suggest a synergistic behavior of Scw4p, Scw10p and Bgl2p, whereas the Scw11p acts antagonistically to those proteins.

S. cerevisiae cell wall; Scw proteins; cell wall proteins

nije evidentirano