Conserved Processes and Lineage-Specific Proteins in Fungal Cell Wall Evolution

Abstract

The cell wall is a defining organelle that differentiates fungi from its sister clades in the opisthokont superkingdom. With a sensitive technique to align low-complexity protein sequences, we have identified 187 cell wall-related proteins in Saccharomyces cerevisiae and determined the presence or absence of homologs in 17 other fungal genomes. There were both conserved and lineage-specific cell wall proteins, and the degree of conservation was strongly correlated with protein function. Some functional classes were poorly conserved and lineage specific: adhesins, structural wall glycoprotein components, and unannotated open reading frames. These proteins are primarily those that are constituents of the walls themselves. On the other hand, glycosyl hydrolases and transferases, proteases, lipases, proteins in the glycosyl phosphatidyl-inositol-protein synthesis pathway, and chaperones were strongly conserved. Many of these proteins are also conserved in other eukaryotes and are associated with wall synthesis in plants. This gene conservation, along with known similarities in wall architecture, implies that the basic architecture of fungal walls is ancestral to the divergence of the ascomycetes and basidiomycetes. The contrasting lineage specificity of wall resident proteins implies diversification. Therefore, fungal cell walls consist of rapidly diversifying proteins that are assembled by the products of an ancestral and conserved set of genes.

On the evolution of fungal and yeast cell walls

“…These two classes differ in functions, amino acid sequences, composition and evolutionary histories. In a study of 183 S. cerevisiae cell wall-associated genes (as determined from the GO annotation) and their paralogues, we found a high degree of conservation of cell wall biosynthetic and processing enzymes across 18 fungal genomes and in other eukaryote kingdoms [16,27]. Many of these proteins, mostly not actually located in the wall, have average amino acid composition of globular proteins, and are well aligned by standard techniques, and their evolutionary histories have been well characterized [47].…”

Retrospective environmental risk assessment of human pharmaceuticals in the Nordic countries 1997-2007

“…Vidare så kan man konstatera att design och funktion av många viktiga biologiska receptorer konserverats under evolutionen vilket gör det troligt att ett potent humanläkemedel även kommer att inducera en biologisk effekt i vattenlevande organismer vid låga koncentrationer. Det kommer nödvändigtvis inte vara samma receptorsvar eller effekt som induceras i männsika men läkemedlet kommer förmodlingen ge upphov till en effekt hos den organism som exponeras (Borenstein et al, 2007, Coronado et al, 2007, Gunnarsson et al, 2008.…”

“…There are of course examples of pharmaceuticals without any receptor specificity such as electrolytes but the overwhelming majority of pharmaceuticals target certain receptors. The conservation of the biological receptors throughout the evolution of species renders it very likely that a potent human pharmaceutical will also affect other species at rather low effect concentrations even though the receptor response might be different from the response induced in humans (Borenstein et al, 2007, Coronado et al, 2007, Gunnarsson et al, 2008.…”

ProFASTA: A pipeline web server for fungal protein scanning with integration of cell surface prediction software

“…GPI proteins, whose final destination can be either the plasma membrane or the cell wall, usually are modular proteins with a functional domain followed by regions of low complexity (Coronado et al, 2007;De Groot et al, 2005). The latter are often rich in serine (S) and threonine (T) residues or contain short stretches with a very high S/T content (Caro et al, 1997;De Groot et al, 2003;Frieman and Cormack 2004;Nather and Munro 2008;Richard and Plaine 2007).…”