Journal
FUNGAL GENETICS AND BIOLOGY
Volume 49, Issue 12, Pages 1033-1043Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.fgb.2012.08.010
Keywords
Aspergillus nidulans; Galactofuranose; UDP-galactopyranose mutase; UDP-glucose/galactose-4-epimerase; UDP-galactofuranose transporter; alcA promoter
Categories
Funding
- Canadian Institutes of Health Research Regional Partnership Program
- Natural Sciences and Engineering Research Council of Canada Discovery Grant program
- Egyptian Ministry of Higher Education
- University of Saskatchewan (UofS)
- UofS
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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 (Gall) 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 Gall 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. Calf immunolocalization using the L10 monoclonal antibody showed that ugmA deletion and repression phenotypes correlated with loss of hyphal wall Calf. 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. Gall appears to play an important role in A. nidulans growth and vigor. (C) 2012 Elsevier Inc. All rights reserved.
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