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Acosta-Zaldivar M, Qi W, Liu NN, Diray-Arce J, Walker LA, Kottom TJ, Kelly R, Yuan M, Asara JM, Lasky-Su JA, Levy O, Limper AH, Gow NAR, Köhler JR. Candida albicans phosphate transport, facilitating nucleotide sugar biosynthesis, contributes to cell wall stability. Access Microbiol 2021. [DOI: 10.1099/acmi.cc2021.po0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The Candida albicans high-affinity phosphate transporter Pho84 is required for normal Target of Rapamycin signaling, oxidative stress resistance and virulence of this fungal pathogen. It also contributes to C. albicans’ tolerance of two antifungal drug classes, polyenes and echinocandins. Echinocandins inhibit biosynthesis of a major cell wall component, beta-1,3-glucan. Cells lacking Pho84 were hypersensitive to other forms of cell wall stress beyond echinocandin exposure, while their cell wall integrity signaling response was weak. Metabolomics experiments showed that levels of phosphoric intermediates, including nucleotides like ATP and nucleotide sugars, were low in pho84 mutant compared to wild type cells recovering from phosphate starvation. Non-phosphoric precursors like nucleobases and nucleosides were elevated. Outer cell wall phosphomannan biosynthesis requires a nucleotide sugar,GDP-mannose. The nucleotide sugar UDP-glucose is the substrate of enzymes that synthesize two major structural cell wall polysaccharides, beta-1,3- and beta-1,6-glucan. Another nucleotide sugar, UDP-N-acetylglucosamine, is the substrate of chitin synthases which produce a stabilizing component of the intercellular septum and of lateral cell walls. Lack of Pho84 activity, and phosphate starvation, potentiated pharmacological or genetic perturbation of these enzymes. Our model is that low substrate concentrations of beta-D-glucan- and chitin synthases diminish enzymatic reaction rates and potentiate pharmacologic inhibitors to decrease the yield of their cell wall-stabilizing products. Phosphate import is not conserved between fungal and human cells, and humans do not synthesize beta-D-glucans or chitin. Hence inhibiting these processes simultaneously could yield potent antifungal effects with low toxicity to humans.
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Affiliation(s)
| | - Wanjun Qi
- Boston Children's Hospital/ Harvard Medical School, USA
| | - Ning-Ning Liu
- School of Public Health, Shanghai Jiao Tong University
| | - Joann Diray-Arce
- Precision Vaccines Program, Boston Children’s Hospital
- Boston Children's Hospital/ Harvard Medical School, USA
| | - Louise A. Walker
- Medical Research Council Centre for Medical Mycology at the University of Aberdeen, United Kingdom
| | - Theodore J. Kottom
- Thoracic Diseases Research Unit, Departments of Medicine and Biochemistry
| | - Rachel Kelly
- Channing Division of Network Medicine, Brigham and Women’s Hospital/Harvard Medical School
| | - Min Yuan
- Division of Signal Transduction and Mass Spectrometry Core, Beth Israel Deaconess Medical Center
| | - John M. Asara
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and Department of Medicine
| | - Jessica Ann Lasky-Su
- Channing Division of Network Medicine, Brigham and Women’s Hospital/Harvard Medical School
| | - Ofer Levy
- Precision Vaccines Program, Boston Children’s Hospital
- Boston Children's Hospital/ Harvard Medical School, USA
| | - Andrew H. Limper
- Thoracic Diseases Research Unit, Departments of Medicine and Biochemistry
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