Papel de la N-glicosilación de proteinas en la virulencia de Fusarium oxysporum

Protein glycosylation is a process widely studied in eukaryotes, localized in two different cellular compartments but functionally connected: the endoplasmic reticulum and the Golgi apparatus. Due to the complexity and diversity of its reactions, some enzymatic pathways are still unknown in many organisms, emerging as new research topics in filamentous fungi. The initial glycosylation steps localized in the ER are highly conserved in eukaryotes, by contrast GA steps show wide variations in the sequential addition of monosaccharides that conform the elongation of the previously synthesized glycans, being some of these enzymatic reactions substrate specific. Protein glycosylation in mammalian species presents a high structural diversity in which glycans are decorated by fucose, xilose, glucose, sialic acid and mannose in terminal positions. Fungal and yeast have less diversity and only present galactose, glucose, uronic acids and mannose as terminal residues. N-acetylglucosamine transferases participate in terminal glycosylation, attaching GlcNAc to enlarge glycan molecules, but considering other studies on eukaryotes, this monosaccharide can be localized in terminal position or at bisecting points in the polysaccharide chains. With the aim to decipher the molecular dialogue and cross talk between Fusarium oxysporum f.sp. lycopersci and the host during infection and to understand the molecular bases that govern fungal pathogenicity, we have analyzed the genes encoding N-acetylglucosaminyl transferases, presumably involved in glycosylation of glycoproteins, glycolipids, proteoglycans or small molecule acceptors. In silico analysis revealed the existence of seven putative N-glycosyl transferase encoding genes in the F. oxysporum f.sp. lycopersici genome. Deletion mutants in the N-acetylglucosaminyl transferase gene gnt2 showed a dramatic reduction in virulence on both plant and animal hosts. The Δgnt2 mutants had alterations in cell wall properties related to terminal α- or β-linked N-acetylglucosamine. In the ...