Fungal cell wall biogenesis: building a dynamic interface with the environment.

Developing an outer protective layer, namely the cell wall, is critical for growth and survival of the fungal cell in the diverse environments where fungi live. The eukaryotic nature of fungi makes the fungal cell a good model for addressing scientific questions related to the structure and function of this external layer in higher organisms. For decades, fungal cell wall studies relied mostly on the biochemical characterization of the major structural components, namely polysaccharides and proteins, and their biosynthesis. The introduction of gene cloningmethodology allowed the identification and characterization of specific cell wall genes, which were cloned based on the information provided by their coded proteins. Genetic strategies also led to important breakthroughs with the isolation of cell wall mutants from species that were amenable to genetic analysis, especially the budding yeast Saccharomyces cerevisiae. These mutants were also the basis for identification of cell-wall-related genes. Molecular approaches thus became the obvious strategy to look into the essential question of cell wall biogenesis, which aims to understand the functions involved in designing the architecture and building the wall structure that serves as an interface of the cell with the environment.