PMT4 Is Involved in -Glycosylation, Cell Wall Organization, Membrane Integrity, and Virulence.

Proteins found within the fungal cell wall usually contain both - and -oligosaccharides. -glycosylation is the process where these oligosaccharides (hereinafter: glycans) are attached to asparagine residues, while in -glycosylation the glycans are covalently bound to serine or threonine residues. The family is grouped into , , and subfamilies. Using bioinformatics analysis within the genome database, an ortholog to Pmt4 and other fungal species was identified. The aim of this study was to assess the relevance of the gene in glycosylation. For this purpose, the gene was disrupted by homologous recombination in the B05.10 strain using a hygromycin B resistance cassette. Expression of in Δ or Δ null mutants restored glycan levels like those observed in the parental strain. The phenotypic analysis showed that Δ null mutants exhibited significant changes in hyphal cell wall composition, including reduced mannan levels and increased amounts of chitin and glucan. Furthermore, the loss of led to decreased glycosylation of glycoproteins in the cell wall. The null mutant lacking was hypersensitive to a range of cell wall perturbing agents, antifungal drugs, and high hydrostatic pressure. Thus, in addition to their role in glycosylation, the is required to virulence, biofilm formation, and membrane integrity. This study adds to our knowledge of the role of the gene, which is involved in glycosylation and cell biology, cell wall formation, and antifungal response.