Reliable Approach for Pure Yeast Cell Wall Protein Isolation from Saccharomyces cerevisiae Yeast Cells

Saccharomyces cerevisiae yeast is a fungus presenting a peripheral organelle called the cell wall. The cell wall protects the yeast cell from stress and provides means for communication with the surrounding environment. It has a complex molecular structure, composed of an internal part of cross-linked polysaccharides and an external part of mannoproteins. These latter are very interesting owing to their functional properties, dependent on their molecular features with massive mannosylations. Therefore, the molecular characterization of mannopro-teins is a must relying on the optimal isolation and preparation of the cell wall fraction. Multiple methods are well reported for yeast cell wall isolation. The most applied one consists of yeast cell lysis by mechanical disruption. However, applying this classical approach to S288C yeast cells showed considerable contamination with noncell wall proteins, mainly comprising mitochondrial proteins. Herein, we tried to further purify the yeast cell wall preparation by two means: ultracentrifugation and Triton X-100 addition. While the first strategy showed limited outcomes in mitochondrial protein removal, the second strategy showed optimal results when Triton X-100 was added at 5%, allowing the identification of more mannoproteins and significantly enriching their amounts. This promising method could be reliably implemented on the lab scale for identification of mannoproteins and molecular characterization and industrial processes for "pure" cell wall isolation.