Characterization of an N-acetylglucosaminyltransferase involved in Aspergillus fumigatus zwitterionic glycoinositolphosphoceramide biosynthesis

In this study, we identified an A. fumigatus N-acetylglucosaminyltransferase, named GntA, and demonstrate its involvement in the initiation of zwitterionic GIPC biosynthesis. Targeted deletion of the gene encoding GntA in A. fumigatus resulted in complete absence of zwitterionic GIPC; a phenotype that could be reverted by episomal expression of GntA in the mutant. The N-acetylhexosaminyltransferase activity of GntA was substantiated by production of N-acetylhexosamine-IPC in the yeast Saccharomyces cerevisiae upon GntA expression. Using an in vitro assay, GntA was furthermore shown to use UDP-N-acetylglucosamine as donor substrate to generate a glycolipid product resistant to saponification and to digestion by phosphatidylinositol-phospholipase C as expected for GlcNAcα1,2IPC. Finally, as the enzymes involved in mannosylation of IPC, GntA was localized to the Golgi apparatus, the site of IPC synthesis.

Source: Glycobiology - November 5, 2015 Category: Biology Authors: Engel, J., Schmalhorst, P. S., Krüger, A. T., Müller, C. T., Buettner, F. F. R., Routier, F. H. Tags: Glycan Metabolism Source Type: research