Aspergillus nidulans galactofuranose biosynthesis affects antifungal drug sensitivity.
The cell wall is essential for fungal survival in natural environments. Many fungal wall carbohydrates are absent from humans, so they are a promising source of antifungal drug targets. Galactofuranose (Galf) is a sugar that decorates certain carbohydrates and lipids. It comprises about 5% of the Aspergillus fumigatus cell wall, and may play a role in systemic aspergillosis. We are studying Aspergillus wall formation in the tractable model system, A. nidulans. Previously we showed single-gene deletions of three sequential A. nidulans Galf biosynthesis proteins each caused similar hyphal morphogenesis defects and 500-fold reduced colony growth and sporulation. Here, we generated ugeA, ugmA and ugtA strains controlled by the alcA(p) or niiA(p) regulatable promoters. For repression and expression, alcA(p)-regulated strains were grown on complete medium with glucose or threonine, whereas niiA(p)-regulated strains were grown on minimal medium with ammonium or nitrate. Expression was assessed by qPCR and colony phenotype. The alcA(p) and niiA(p) strains produced similar effects: colonies resembling wild type for gene expression, and resembling deletion strains for gene repression. Galf immunolocalization using the L10 monoclonal antibody showed that ugmA deletion and repression phenotypes correlated with loss of hyphal wall Galf. None of the gene manipulations affected itraconazole sensitivity, as expected. Deletion of any of ugmA, ugeA, ugtA, their repression by alcA(p) or niiA(p), OR, ugmA overexpression by alcA(p), increased sensitivity to Caspofungin. Strains with alcA(p)-mediated overexpression of ugeA and ugtA had lower caspofungin sensitivity. Galf appears to play an important role in A. nidulans growth and vigor.
Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, Canada S7N 5E2.
Md Kausar
MK
Alam
Amira M
AM
El-Ganiny
Sharmin
S
Afroz
David A R
DA
Sanders
Juxin
J
Liu
Susan G W
SG
Kaminskyj
D000935:Antifungal Agents / Q000494:pharmacology*; D001233:Aspergillus nidulans / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics; D000077336:Caspofungin; D003470:Culture Media / Q000737:chemistry; D054714:Echinocandins / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005690:Galactose / Q000031:analogs & derivatives* / Q000096:biosynthesis*; D015870:Gene Expression; D020869:Gene Expression Profiling; D025301:Hyphae / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D017964:Itraconazole / Q000494:pharmacology; D055666:Lipopeptides; D008826:Microbial Sensitivity Tests; D011401:Promoter Regions, Genetic; D060888:Real-Time Polymerase Chain Reaction
D000935:Antifungal Agents; D003470:Culture Media; D054714:Echinocandins; D005656:Fungal Proteins; D055666:Lipopeptides; D017964:Itraconazole; D000077336:Caspofungin; D005690:Galactose