Genetic validation of Aspergillus fumigatus phosphoglucomutase as a viable therapeutic target in invasive aspergillosis |
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Authors: | Kaizhou Yan Mathew Stanley Bartosz Kowalski Olawale G. Raimi Andrew T. Ferenbach Pingzhen Wei Wenxia Fang Daan M.F. van Aalten |
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Affiliation: | 1.Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom;2.National Engineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning, China |
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Abstract: | Aspergillus fumigatus is the causative agent of invasive aspergillosis, an infection with mortality rates of up to 50%. The glucan-rich cell wall of A. fumigatus is a protective structure that is absent from human cells and is a potential target for antifungal treatments. Glucan is synthesized from the donor uridine diphosphate glucose, with the conversion of glucose-6-phosphate to glucose-1-phosphate by the enzyme phosphoglucomutase (PGM) representing a key step in its biosynthesis. Here, we explore the possibility of selectively targeting A. fumigatus PGM (AfPGM) as an antifungal treatment strategy. Using a promoter replacement strategy, we constructed a conditional pgm mutant and revealed that pgm is required for A. fumigatus growth and cell wall integrity. In addition, using a fragment screen, we identified the thiol-reactive compound isothiazolone fragment of PGM as targeting a cysteine residue not conserved in the human ortholog. Furthermore, through scaffold exploration, we synthesized a para-aryl derivative (ISFP10) and demonstrated that it inhibits AfPGM with an IC50 of 2 μM and exhibits 50-fold selectivity over the human enzyme. Taken together, our data provide genetic validation of PGM as a therapeutic target and suggest new avenues for inhibiting AfPGM using covalent inhibitors that could serve as tools for chemical validation. |
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Keywords: | Aspergillus fumigatus phosphoglucomutase covalent inhibitor isothiazolone antifungal fragment FBDD |
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