Deciphering the effect of N-glycosylation pathway deletion in Aspergillus nidulans enzymes secretion

Abstract

The genus Aspergillus includes microorganisms that naturally degrade lignocellulosic biomass, secreting large amounts of carbohydrate-active enzymes (CAZymes), what characterizes their saprophytic lifestyle. Among other CAZymes, ²-xylosidases are glycosyl hydrolases (GHs) that aid in the degradation of plant biomass by releasing xylose from xylooligosaccharides in the complete degradation of hemicellulose. In addition to the capacity of secreting large quantities and a variety of enzymes, A. nidulans is am model organism having a well-characterized sexual cycle and a manipulable genetic system, giving advantages to the development and construction of mutant strains. Aspergillus is capable of performing post-translational modifications (PTMs) such as proteolytic cleavage, disulfide bond formation and glycosylation of proteins, providing an additional advantage for the use of such organisms as a host for large-scale protein production. Asparagine-linked protein N-glycosylation is a prevalent PTM in eukaryotic systems. N-glycosylation of proteins is essential for a range of cellular processes such as immune responses, cellular communication, intracellular trafficking, stability, secretion, folding and protein activity. Based on preliminary data, our hypothesis is that the deletion of genes involved in the N-glycan assembly in A. nidulans can modulate the secretion of a target protein or proteins in general. Initially, an A. nidulans strain overexpressing a homologous ²-xylosidase (AN8401) will be the model strain for deletion of some genes associated with the N-glycosylation pathway. The influence of genes deletion will be then evaluated in relation to fungal growth, ²-xylosidase secretion and total protein secretion. (AU)