Functional YFP-tagging of the essential GDP-mannose transporter reveals an important role for the secretion related small GTPase SrgC protein in maintenance of Golgi bodies in Aspergillus niger

Biosynthesis of the Fungal Cell Wall Polysaccharide Galactomannan Requires Intraluminal GDP-mannose

“…The gene AFUA_ 5G05740, named here gmtA, encodes a 382-amino acid protein displaying 50% identity with S. cerevisiae Vrg4p on the amino acid sequence level and clustering with other characterized GDP-Man transporters in phylogenetic analyses (26). The ability of GmtA to complement the lethal phenotype of a conditional S. cerevisiae VRG4 knock-out strain, generated by replacing the endogenous VRG4 promoter region with a galactoseinducible promoter, demonstrates that it is an active GDP-Man transporter (supplemental Fig.…”

“…The conidia swelled up to 8-fold the volume of swollen wild type conidia and frequently burst before or shortly after the emergence of the germ tube. (26). Deletion of gmtA is thus expected to abrogate transport of GDP-Man in the Golgi apparatus and interfere with biosynthesis of glycoconjugates.…”

“…GDP-mannose (GDP-Man) transporters have been studied in various organisms, such as the protozoan parasite Leishmania (20), S. cerevisiae (21), plants (22), and various fungi (23)(24)(25), including two Aspergilli (26,27). Mammalian cells do not possess any * This work was supported by the Deutsche Forschungsgemeinschaft.…”

“…In fungi, GDP-Man transport is indispensable for modification of protein N-and O-glycans (28 -30), glycolipid biosynthesis (31), and GPI anchor substitution (32,33). It has been reported to be essential in Saccharomyces (21), Candida (23), and Aspergillus niger (26).…”

Cryptococcus neoformans Dual GDP-Mannose Transporters and Their Role in Biology and Virulence

“…Viable cells that express partly functional mutant Vrg4 have been reported, but these strains show defects in both N-and O-linked protein glycosylation and are more sensitive than their wild-type counterparts to cell wall stress (12,13,19). Single VRG4 homologs have been identified in multiple fungi, including Pichia pastoris (20), Aspergillus niger (21), Aspergillus fumigatus (22), Candida glabrata (23), and Candida albicans (24); all of them complement S. cerevisiae vrg4 mutants. While most of these genes, like the S. cerevisiae VRG4 gene, are essential, it is notable that A. fumigatus cells lacking GmtA are viable although significantly impaired (22).…”