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Chen Y, Gao F, Chen X, Tao S, Chen P, Lin W. The basic leucine zipper transcription factor MeaB is critical for biofilm formation, cell wall integrity, and virulence in Aspergillus fumigatus. mSphere 2024; 9:e0061923. [PMID: 38284755 PMCID: PMC10900910 DOI: 10.1128/msphere.00619-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/18/2023] [Indexed: 01/30/2024] Open
Abstract
The regulation of fungal cell wall biosynthesis is crucial for cell wall integrity maintenance and directly impacts fungal pathogen virulence. Although numerous genes are involved in fungal cell wall polysaccharide biosynthesis through multiple pathways, the underlying regulatory mechanism is still not fully understood. In this study, we identified and functionally characterized a direct downstream target of SomA, the basic-region leucine zipper transcription factor MeaB, playing a certain role in Aspergillus fumigatus cell wall integrity. Loss of meaB reduces hyphal growth, causes severe defects in galactosaminogalactan-mediated biofilm formation, and attenuates virulence in a Galleria mellonella infection model. Furthermore, the meaB null mutant strain exhibited hypersensitivity to cell wall-perturbing agents and significantly alters the cell wall structure. Transcriptional profile analysis revealed that MeaB positively regulates the expression of the galactosaminogalactan biosynthesis and β-1,3-glucanosyltransferase genes uge3, agd3, and sph3 and gel1, gel5, and gel7, respectively, as well as genes involved in amino sugar and nucleotide sugar metabolism. Further study demonstrated that MeaB could respond to cell wall stress and contribute to the proper expression of mitogen-activated protein kinase genes mpkA and mpkC in the presence of different concentrations of congo red. In conclusion, A. fumigatus MeaB plays a critical role in cell wall integrity by governing the expression of genes encoding cell wall-related proteins, thus impacting the virulence of this fungus.IMPORTANCEAspergillus fumigatus is a common opportunistic mold that causes life-threatening infections in immunosuppressed patients. The fungal cell wall is a complex and dynamic organelle essential for the development of pathogenic fungi. Genes involved in cell wall polysaccharide biosynthesis and remodeling are crucial for fungal pathogen virulence. However, the potential regulatory mechanism for cell wall integrity remains to be fully defined in A. fumigatus. In the present study, we identify basic-region leucine zipper transcription factor MeaB as an important regulator of cell wall galactosaminogalactan biosynthesis and β-1,3-glucan remodeling that consequently impacts stress response and virulence of fungal pathogens. Thus, we illuminate a mechanism of transcriptional control fungal cell wall polysaccharide biosynthesis and stress response. As these cell wall components are promising therapeutic targets for fungal infections, understanding the regulatory mechanism of such polysaccharides will provide new therapeutic opportunities.
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Affiliation(s)
- Yuan Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Fei Gao
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Xiaojin Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Siyuan Tao
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Peiying Chen
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
| | - Wei Lin
- Nanjing University of Chinese Medicine, Nanjing Drum Tower Hospital, Nanjing, China
- Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, China
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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2
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Lu Q, Regan DP, Barlow DE, Fears KP. Antimicrobial efficacy of cyclic α- and β-peptides incorporated in polyurethane coatings. Biointerphases 2023; 18:031008. [PMID: 37289032 DOI: 10.1116/6.0002515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/12/2023] [Indexed: 06/09/2023] Open
Abstract
Microbial growth on surfaces poses health concerns and can accelerate the biodegradation of engineered materials and coatings. Cyclic peptides are promising agents to combat biofouling because they are more resistant to enzymatic degradation than their linear counterparts. They can also be designed to interact with extracellular targets and intracellular targets and/or self-assemble into transmembrane pores. Here, we determine the antimicrobial efficacy of two pore-forming cyclic peptides, α-K3W3 and β-K3W3, against bacterial and fungal liquid cultures and their capacity to inhibit biofilm formation on coated surfaces. These peptides display identical sequences, but the additional methylene group in the peptide backbone of β-amino acids results in a larger diameter and an enhancement in the dipole moment. In liquid cultures, β-K3W3 exhibited lower minimum inhibitory concentration values and greater microbicidal power in reducing the number of colony forming units (CFUs) when exposed to a gram-positive bacterium, Staphylococcus aureus, and two fungal strains, Naganishia albida and Papiliotrema laurentii. To evaluate the efficacy against the formation of fungal biofilms on painted surfaces, cyclic peptides were incorporated into polyester-based thermoplastic polyurethane. The formation of N. albida and P. laurentii microcolonies (105 per inoculation) for cells extracted from coatings containing either peptide could not be detected after a 7-day exposure. Moreover, very few CFUs (∼5) formed after 35 days of repeated depositions of freshly cultured P. laurentii every 7 days. In contrast, the number of CFUs for cells extracted from the coating without cyclic peptides was >8 log CFU.
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Affiliation(s)
- Qin Lu
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Daniel P Regan
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Daniel E Barlow
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Kenan P Fears
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
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3
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Zhou Y, Yan K, Qin Q, Raimi OG, Du C, Wang B, Ahamefule CS, Kowalski B, Jin C, van Aalten DMF, Fang W. Phosphoglucose Isomerase Is Important for Aspergillus fumigatus Cell Wall Biogenesis. mBio 2022; 13:e0142622. [PMID: 35913157 PMCID: PMC9426556 DOI: 10.1128/mbio.01426-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Aspergillus fumigatus is a devastating opportunistic fungal pathogen causing hundreds of thousands of deaths every year. Phosphoglucose isomerase (PGI) is a glycolytic enzyme that converts glucose-6-phosphate to fructose-6-phosphate, a key precursor of fungal cell wall biosynthesis. Here, we demonstrate that the growth of A. fumigatus is repressed by the deletion of pgi, which can be rescued by glucose and fructose supplementation in a 1:10 ratio. Even under these optimized growth conditions, the Δpgi mutant exhibits severe cell wall defects, retarded development, and attenuated virulence in Caenorhabditis elegans and Galleria mellonella infection models. To facilitate exploitation of A. fumigatus PGI as an antifungal target, we determined its crystal structure, revealing potential avenues for developing inhibitors, which could potentially be used as adjunctive therapy in combination with other systemic antifungals. IMPORTANCE Aspergillus fumigatus is an opportunistic fungal pathogen causing deadly infections in immunocompromised patients. Enzymes essential for fungal survival and cell wall biosynthesis are considered potential drug targets against A. fumigatus. PGI catalyzes the second step of the glycolysis pathway, linking glycolysis and the pentose phosphate pathway. As such, PGI has been widely considered as a target for metabolic regulation and therefore a therapeutic target against hypoxia-related diseases. Our study here reveals that PGI is important for A. fumigatus survival and exhibit pleiotropic functions, including development, cell wall glucan biosynthesis, and virulence. We also solved the crystal structure of PGI, thus providing the genetic and structural groundwork for the exploitation of PGI as a potential antifungal target.
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Affiliation(s)
- Yao Zhou
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Kaizhou Yan
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Qijian Qin
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Olawale G. Raimi
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Chao Du
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Bin Wang
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Chukwuemeka Samson Ahamefule
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
| | - Bartosz Kowalski
- School of Life Sciences, University of Dundeegrid.8241.f, Dundee, United Kingdom
| | - Cheng Jin
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | | | - Wenxia Fang
- Guangxi Biological Sciences and Biotechnology Center, Guangxi Academy of Sciencesgrid.418329.5, Nanning, Guangxi, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
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4
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Jaber QZ, Logviniuk D, Yona A, Fridman M. Echinocandins Localized to the Target-Harboring Cell Surface Are Not Degraded but Those Entering the Vacuole Are. ACS Chem Biol 2022; 17:1155-1163. [PMID: 35404573 PMCID: PMC9127807 DOI: 10.1021/acschembio.2c00060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Echinocandin antifungal drugs have a broad spectrum of activities and excellent safety profiles. These agents noncompetitively inhibit the formation of the major polysaccharide component of the fungal cell wall, a reaction catalyzed by the membrane-bound β-glucan synthase (GS) protein complex. We have developed fluorescent probes of three echinocandin drugs: caspofungin (CSF), anidulafungin (ANF), and rezafungin (RZF). Fluorescent echinocandins had the same spectrum of activities as the parent echinocandins, supporting the fact that conjugation of the dye did not alter their mode of action. Of the three echinocandins, ANF has the most potent in vitro activity. Investigation of the subcellular distribution of the fluorescent echinocandins in live Candida yeast cells revealed that despite their high structural similarity, each of the drug probes had a unique subcellular distribution pattern. Fluorescent CSF, which is the least potent of the three echinocandins, accumulated in Candida vacuoles; fluorescent ANF localized in the extracellular environment and on the yeast cell surface where the target GS resides; and fluorescent RZF was partitioned between the surface and the vacuole over time. Recovery of fluorescent CSF from Candida cells revealed substantial degradation over time; functional vacuoles were necessary for this degradation. Under the same conditions, fluorescent ANF was not degraded. This study supports the "target-oriented drug subcellular localization" principle. In the case of echinocandins, localization to the cell surface can contribute to improved potency and accumulation in vacuoles induces degradation leading to drug deactivation.
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Curto MÁ, Butassi E, Ribas JC, Svetaz LA, Cortés JCG. Natural products targeting the synthesis of β(1,3)-D-glucan and chitin of the fungal cell wall. Existing drugs and recent findings. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2021; 88:153556. [PMID: 33958276 DOI: 10.1016/j.phymed.2021.153556] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/12/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND During the last three decades systemic fungal infections associated to immunosuppressive therapies have become a serious healthcare problem. Clinical development of new antifungals is an urgent requirement. Since fungal but not mammalian cells are encased in a carbohydrate-containing cell wall, which is required for the growth and viability of fungi, the inhibition of cell wall synthesizing machinery, such as β(1,3)-D-glucan synthases (GS) and chitin synthases (CS) that catalyze the synthesis of β(1-3)-D-glucan and chitin, respectively, represent an ideal mode of action of antifungal agents. Although the echinocandins anidulafungin, caspofungin and micafungin are clinically well-established GS inhibitors for the treatment of invasive fungal infections, much effort must still be made to identify inhibitors of other enzymes and processes involved in the synthesis of the fungal cell wall. PURPOSE Since natural products (NPs) have been the source of several antifungals in clinical use and also have provided important scaffolds for the development of semisynthetic analogues, this review was devoted to investigate the advances made to date in the discovery of NPs from plants that showed capacity of inhibiting cell wall synthesis targets. The chemical characterization, specific target, discovery process, along with the stage of development are provided here. METHODS An extensive systematic search for NPs against the cell wall was performed considering all the articles published until the end of 2020 through the following scientific databases: NCBI PubMed, Scopus and Google Scholar and using the combination of the terms "natural antifungals" and "plant extracts" with "fungal cell wall". RESULTS The first part of this review introduces the state of the art of the structure and biosynthesis of the fungal cell wall and considers exclusively those naturally produced GS antifungals that have given rise to both existing semisynthetic approved drugs and those derivatives currently in clinical trials. According to their chemical structure, natural GS inhibitors can be classified as 1) cyclic lipopeptides, 2) glycolipids and 3) acidic terpenoids. We also included nikkomycins and polyoxins, NPs that inhibit the CS, which have traditionally been considered good candidates for antifungal drug development but have finally been discarded after enduring unsuccessful clinical trials. Finally, the review focuses in the most recent findings about the growing field of plant-derived molecules and extracts that exhibit activity against the fungal cell wall. Thus, this search yielded sixteen articles, nine of which deal with pure compounds and seven with plant extracts or fractions with proven activity against the fungal cell wall. Regarding the mechanism of action, seven (44%) produced GS inhibition while five (31%) inhibited CS. Some of them (56%) interfered with other components of the cell wall. Most of the analyzed articles refer to tests carried out in vitro and therefore are in early stages of development. CONCLUSION This report delivers an overview about both existing natural antifungals targeting GS and CS activities and their mechanisms of action. It also presents recent discoveries on natural products that may be used as starting points for the development of potential selective and non-toxic antifungal drugs.
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Affiliation(s)
- M Ángeles Curto
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Salamanca, Spain
| | - Estefanía Butassi
- Área Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Juan C Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Salamanca, Spain
| | - Laura A Svetaz
- Área Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
| | - Juan C G Cortés
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, Salamanca, Spain.
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6
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Jaber QZ, Bibi M, Ksiezopolska E, Gabaldon T, Berman J, Fridman M. Elevated Vacuolar Uptake of Fluorescently Labeled Antifungal Drug Caspofungin Predicts Echinocandin Resistance in Pathogenic Yeast. ACS CENTRAL SCIENCE 2020; 6:1698-1712. [PMID: 33145409 PMCID: PMC7596861 DOI: 10.1021/acscentsci.0c00813] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Indexed: 06/11/2023]
Abstract
Echinocandins are the newest class of antifungal drugs in clinical use. These agents inhibit β-glucan synthase, which catalyzes the synthesis of β-glucan, an essential component of the fungal cell wall, and have a high clinical efficacy and low toxicity. Echinocandin resistance is largely due to mutations in the gene encoding β-glucan synthase, but the mode of action is not fully understood. We developed fluorescent probes based on caspofungin, the first clinically approved echinocandin, and studied their cellular biology in Candida species, the most common cause of human fungal infections worldwide. Fluorescently labeled caspofungin probes, like the unlabeled drug, were most effective against metabolically active cells. The probes rapidly accumulated in Candida vacuoles, as shown by colocalization with vacuolar proteins and vacuole-specific stains. The uptake of fluorescent caspofungin is facilitated by endocytosis: The labeled drug formed vesicles similar to fluorescently labeled endocytic vesicles, the vacuolar accumulation of fluorescent caspofungin was energy-dependent, and inhibitors of endocytosis reduced its uptake. In a panel comprised of isogenic Candida strains carrying different β-glucan synthase mutations as well as clinical isolates, resistance correlated with increased fluorescent drug uptake into vacuoles. Fluorescent drug uptake also associated with elevated levels of chitin, a sugar polymer that increases cell-wall rigidity. Monitoring the intracellular uptake of fluorescent caspofungin provides a rapid and simple assay that can enable the prediction of echinocandin resistance, which is useful for research applications as well as for selecting the appropriate drugs for treatments of invasive fungal infections.
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Affiliation(s)
- Qais Z. Jaber
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Maayan Bibi
- School
of Molecular Cell Biology and Biotechnology, George Wise Faculty of
Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ewa Ksiezopolska
- Barcelona
Supercomputing Centre (BSC−CNS) Jordi Girona, 29, Barcelona 08034, Spain
- Institute
for Research in Biomedicine, The Barcelona
Institute of Science and Technology, Baldiri Reixac, 10, Barcelona 08028, Spain
| | - Toni Gabaldon
- Barcelona
Supercomputing Centre (BSC−CNS) Jordi Girona, 29, Barcelona 08034, Spain
- Institute
for Research in Biomedicine, The Barcelona
Institute of Science and Technology, Baldiri Reixac, 10, Barcelona 08028, Spain
- Catalan
Institution for Research and Advanced Studies, Passeig de Lluís Companys, 23, Barcelona 08010, Spain
| | - Judith Berman
- School
of Molecular Cell Biology and Biotechnology, George Wise Faculty of
Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Micha Fridman
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
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7
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Fang W, Sanz AB, Bartual SG, Wang B, Ferenbach AT, Farkaš V, Hurtado-Guerrero R, Arroyo J, van Aalten DMF. Mechanisms of redundancy and specificity of the Aspergillus fumigatus Crh transglycosylases. Nat Commun 2019; 10:1669. [PMID: 30971696 PMCID: PMC6458159 DOI: 10.1038/s41467-019-09674-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/20/2019] [Indexed: 11/13/2022] Open
Abstract
Fungal cell wall synthesis is achieved by a balance of glycosyltransferase, hydrolase and transglycosylase activities. Transglycosylases strengthen the cell wall by forming a rigid network of crosslinks through mechanisms that remain to be explored. Here we study the function of the Aspergillus fumigatus family of five Crh transglycosylases. Although crh genes are dispensable for cell viability, simultaneous deletion of all genes renders cells sensitive to cell wall interfering compounds. In vitro biochemical assays and localisation studies demonstrate that this family of enzymes functions redundantly as transglycosylases for both chitin-glucan and chitin-chitin cell wall crosslinks. To understand the molecular basis of this acceptor promiscuity, we solved the crystal structure of A. fumigatus Crh5 (AfCrh5) in complex with a chitooligosaccharide at the resolution of 2.8 Å, revealing an extensive elongated binding cleft for the donor (−4 to −1) substrate and a short acceptor (+1 to +2) binding site. Together with mutagenesis, the structure suggests a “hydrolysis product assisted” molecular mechanism favouring transglycosylation over hydrolysis. Transglycosylases strengthen the fungal cell wall by forming a rigid network of crosslinks. Here, Fang et al. show that the five Crh transglycosylases of Aspergillus fumigatus are dispensable for cell wall integrity in vitro, and solve the crystal structure of Crh5 in complex with chitooligosaccharides.
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Affiliation(s)
- Wenxia Fang
- School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.,National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007, Nanning, China
| | - Ana Belén Sanz
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain
| | | | - Bin Wang
- National Engineering Research Center for Non-Food Biorefinery, State Key Laboratory of Non-Food Biomass and Enzyme Technology, Guangxi Academy of Sciences, 530007, Nanning, China
| | | | - Vladimír Farkaš
- Department of Glycobiology, Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, 84538, Bratislava, Slovakia
| | - Ramon Hurtado-Guerrero
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC), 50018, Zaragoza, Spain.,Fundación ARAID, Av. de Ranillas, 50018, Zaragoza, Spain
| | - Javier Arroyo
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
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Kadry AA, El-Ganiny AM, Mosbah RA, Kaminskyj SGW. Deletion of Aspergillus nidulans GDP-mannose transporters affects hyphal morphometry, cell wall architecture, spore surface character, cell adhesion, and biofilm formation. Med Mycol 2018; 56:621-630. [PMID: 29420778 DOI: 10.1093/mmy/myx082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
Systemic human fungal infections are increasingly common. Aspergillus species cause most of the airborne fungal infections. Life-threatening invasive aspergillosis was formerly found only in immune-suppressed patients, but recently some strains of A. fumigatus have become primary pathogens. Many fungal cell wall components are absent from mammalian systems, so they are potential drug targets. Cell-wall-targeting drugs such as echinocandins are used clinically, although echinocandin-resistant strains were discovered shortly after their introduction. Currently there are no fully effective anti-fungal drugs. Fungal cell wall glycoconjugates modulate human immune responses, as well as fungal cell adhesion, biofilm formation, and drug resistance. Guanosine diphosphate (GDP) mannose transporters (GMTs) transfer GDP-mannose from the cytosol to the Golgi lumen prior to mannosylation. Aspergillus nidulans GMTs are encoded by gmtA and gmtB. Here we elucidate the roles of A. nidulans GMTs. Strains engineered to lack either or both GMTs were assessed for hyphal and colonial morphology, cell wall ultrastructure, antifungal susceptibility, spore hydrophobicity, adherence and biofilm formation. The gmt-deleted strains had smaller colonies with reduced sporulation and with thicker hyphal walls. The gmtA deficient spores had reduced hydrophobicity and were less adherent and less able to form biofilms in vitro. Thus, gmtA not only participates in maintaining the cell wall integrity but also plays an important role in biofilm establishment and adherence of A. nidulans. These findings suggested that GMTs have roles in A. nidulans growth and cell-cell interaction and could be a potential target for new antifungals that target virulence determinants.
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Affiliation(s)
- Ashraf A Kadry
- Microbiology and Immunology Department, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Amira M El-Ganiny
- Microbiology and Immunology Department, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Rasha A Mosbah
- Microbiology and Immunology Department, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt.,Zagazig University Hospitals, Zagazig, Egypt
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9
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Eldesouky HE, Li X, Abutaleb NS, Mohammad H, Seleem MN. Synergistic interactions of sulfamethoxazole and azole antifungal drugs against emerging multidrug-resistant Candida auris. Int J Antimicrob Agents 2018; 52:754-761. [PMID: 30145250 DOI: 10.1016/j.ijantimicag.2018.08.016] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/15/2018] [Accepted: 08/18/2018] [Indexed: 01/05/2023]
Abstract
Candida auris is an emerging multidrug-resistant pathogen implicated in numerous outbreaks worldwide, with a notably high mortality rate (ca. 60%). A significant challenge with treatment of these infections is the resistance of C. auris to most antifungal drugs used clinically. Thus, finding co-drugs capable of overcoming resistance to frontline antifungals is of prime clinical importance. In this study, the ability of the combination of different sulfa drugs with azole antifungals to inhibit the growth of azole-resistant C. auris isolates was evaluated. Among the active sulfa drugs, sulfamethoxazole exhibited the most potent in vitro synergistic interactions with voriconazole and itraconazole. The sulfamethoxazole-voriconazole combination restored voriconazole's fungistatic activity against three of eight voriconazole-resistant clinical isolates. Similarly, the sulfamethoxazole-itraconazole combination restored itraconazole's fungistatic activity against three of four itraconazole-resistant clinical isolates. This activity was further confirmed in vivo in a Caenorhabditis elegans model of C. auris infection. The sulfamethoxazole-voriconazole combination enhanced survival of nematodes infected with C. auris by nearly 70%. Notably, these data indicate that the efficacy of this novel combination is dependent on the underlying mechanism of azole resistance. Mutant strains demonstrating azole resistance by either overproduction of or decreased affinity for the azole target (ERG11p) were found highly to be susceptible to the sulfamethoxazole-azole combination. However, this synergistic interaction was ineffective against mutant strains that demonstrated azole resistance via efflux pump hyperactivity. In conclusion, sulfamethoxazole represents a promising co-drug that can restore the efficacy of certain azole antifungal drugs against some azole-resistant isolates of C. auris.
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Affiliation(s)
- Hassan E Eldesouky
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
| | - Xiaoyan Li
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA; College of Life Sciences, Northeast Forestry University, Harbin, Heilongjiang, China
| | - Nader S Abutaleb
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
| | - Haroon Mohammad
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
| | - Mohamed N Seleem
- Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute of Inflammation, Immunology, and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA.
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10
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Samalova M, Mélida H, Vilaplana F, Bulone V, Soanes DM, Talbot NJ, Gurr SJ. The β-1,3-glucanosyltransferases (Gels) affect the structure of the rice blast fungal cell wall during appressorium-mediated plant infection. Cell Microbiol 2016; 19. [PMID: 27568483 PMCID: PMC5396357 DOI: 10.1111/cmi.12659] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/23/2016] [Accepted: 08/24/2016] [Indexed: 12/02/2022]
Abstract
The fungal wall is pivotal for cell shape and function, and in interfacial protection during host infection and environmental challenge. Here, we provide the first description of the carbohydrate composition and structure of the cell wall of the rice blast fungus Magnaporthe oryzae. We focus on the family of glucan elongation proteins (Gels) and characterize five putative β‐1,3‐glucan glucanosyltransferases that each carry the Glycoside Hydrolase 72 signature. We generated targeted deletion mutants of all Gel isoforms, that is, the GH72+, which carry a putative carbohydrate‐binding module, and the GH72− Gels, without this motif. We reveal that M. oryzaeGH72+GELs are expressed in spores and during both infective and vegetative growth, but each individual Gel enzymes are dispensable for pathogenicity. Further, we demonstrated that a Δgel1Δgel3Δgel4 null mutant has a modified cell wall in which 1,3‐glucans have a higher degree of polymerization and are less branched than the wild‐type strain. The mutant showed significant differences in global patterns of gene expression, a hyper‐branching phenotype and no sporulation, and thus was unable to cause rice blast lesions (except via wounded tissues). We conclude that Gel proteins play significant roles in structural modification of the fungal cell wall during appressorium‐mediated plant infection.
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Affiliation(s)
| | - Hugo Mélida
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.,Centre for Plant Biotechnology and Genomics, Universidad Politécnica de Madrid, Madrid, Spain
| | - Francisco Vilaplana
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Vincent Bulone
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.,ARC Centre of Excellence in Plant Cell Walls and School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, South Australia, Australia
| | - Darren M Soanes
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Nicholas J Talbot
- School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Sarah J Gurr
- Department of Plant Sciences, University of Oxford, Oxford, UK.,School of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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Arroyo J, Farkaš V, Sanz AB, Cabib E. ‘Strengthening the fungal cell wall through chitin-glucan cross-links: effects on morphogenesis and cell integrity’. Cell Microbiol 2016; 18:1239-50. [DOI: 10.1111/cmi.12615] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/09/2016] [Accepted: 05/12/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Javier Arroyo
- Departamento de Microbiología II, Facultad de Farmacia; Universidad Complutense de Madrid, IRYCIS; 28040 Madrid Spain
| | - Vladimír Farkaš
- Institute of Chemistry, Center for Glycomics; Department of Glycobiology, Slovak Academy of Sciences; 84538 Bratislava Slovakia
| | - Ana Belén Sanz
- Departamento de Microbiología II, Facultad de Farmacia; Universidad Complutense de Madrid, IRYCIS; 28040 Madrid Spain
| | - Enrico Cabib
- Laboratory of Biochemistry and Genetics, NIDDK, National Institutes of Health; Department of Health and Human Services; Bethesda MD USA
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12
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Synthesis and biological evaluation of novel phosphoramidate derivatives of coumarin as chitin synthase inhibitors and antifungal agents. Eur J Med Chem 2016; 108:166-176. [DOI: 10.1016/j.ejmech.2015.11.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 11/16/2015] [Accepted: 11/18/2015] [Indexed: 11/22/2022]
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13
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García R, Botet J, Rodríguez-Peña JM, Bermejo C, Ribas JC, Revuelta JL, Nombela C, Arroyo J. Genomic profiling of fungal cell wall-interfering compounds: identification of a common gene signature. BMC Genomics 2015; 16:683. [PMID: 26341223 PMCID: PMC4560923 DOI: 10.1186/s12864-015-1879-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 08/25/2015] [Indexed: 01/01/2023] Open
Abstract
Background The fungal cell wall forms a compact network whose integrity is essential for cell morphology and viability. Thus, fungal cells have evolved mechanisms to elicit adequate adaptive responses when cell wall integrity (CWI) is compromised. Functional genomic approaches provide a unique opportunity to globally characterize these adaptive mechanisms. To provide a global perspective on these CWI regulatory mechanisms, we developed chemical-genomic profiling of haploid mutant budding yeast cells to systematically identify in parallel those genes required to cope with stresses interfering the cell wall by different modes of action: β-1,3 glucanase and chitinase activities (zymolyase), inhibition of β-1,3 glucan synthase (caspofungin) and binding to chitin (Congo red). Results Measurement of the relative fitness of the whole collection of 4786 haploid budding yeast knock-out mutants identified 222 mutants hypersensitive to caspofungin, 154 mutants hypersensitive to zymolyase, and 446 mutants hypersensitive to Congo red. Functional profiling uncovered both common and specific requirements to cope with different cell wall damages. We identified a cluster of 43 genes highly important for the integrity of the cell wall as the common “signature of cell wall maintenance (CWM)”. This cluster was enriched in genes related to vesicular trafficking and transport, cell wall remodeling and morphogenesis, transcription and chromatin remodeling, signal transduction and RNA metabolism. Although the CWI pathway is the main MAPK pathway regulating cell wall integrity, the collaboration with other signal transduction pathways like the HOG pathway and the invasive growth pathway is also required to cope with the cell wall damage depending on the nature of the stress. Finally, 25 mutant strains showed enhanced caspofungin resistance, including 13 that had not been previously identified. Only three of them, wsc1Δ, elo2Δ and elo3Δ, showed a significant decrease in β-1,3-glucan synthase activity. Conclusions This work provides a global perspective about the mechanisms involved in cell wall stress adaptive responses and the cellular functions required for cell wall integrity. The results may be useful to uncover new potential antifungal targets and develop efficient antifungal strategies by combination of two drugs, one targeting the cell wall and the other interfering with the adaptive mechanisms. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1879-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Raúl García
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
| | - Javier Botet
- Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
| | - José Manuel Rodríguez-Peña
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
| | - Clara Bermejo
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
| | - Juan Carlos Ribas
- Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain. .,Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Universidad de Salamanca, 37007, Salamanca, Spain.
| | - José Luis Revuelta
- Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain.
| | - César Nombela
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
| | - Javier Arroyo
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, 28040, Madrid, Spain.
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Rak M, Salome M, Kaminskyj SGW, Gough KM. X-ray microfluorescence (μXRF) imaging of Aspergillus nidulans cell wall mutants reveals biochemical changes due to gene deletions. Anal Bioanal Chem 2014; 406:2809-16. [DOI: 10.1007/s00216-014-7726-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 02/05/2014] [Accepted: 02/25/2014] [Indexed: 10/25/2022]
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pH signaling in human fungal pathogens: a new target for antifungal strategies. EUKARYOTIC CELL 2014; 13:342-52. [PMID: 24442891 DOI: 10.1128/ec.00313-13] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fungi are exposed to broadly fluctuating environmental conditions, to which adaptation is crucial for their survival. An ability to respond to a wide pH range, in particular, allows them to cope with rapid changes in their extracellular settings. PacC/Rim signaling elicits the primary pH response in both model and pathogenic fungi and has been studied in multiple fungal species. In the predominant human pathogenic fungi, namely, Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans, this pathway is required for many functions associated with pathogenesis and virulence. Aspects of this pathway are fungus specific and do not exist in mammalian cells. In this review, we highlight recent advances in our understanding of PacC/Rim-mediated functions and discuss the growing interest in this cascade and its factors as potential drug targets for antifungal strategies. We focus on both conserved and distinctive features in model and pathogenic fungi, highlighting the specificities of PacC/Rim signaling in C. albicans, A. fumigatus, and C. neoformans. We consider the role of this pathway in fungal virulence, including modulation of the host immune response. Finally, as now recognized for other signaling cascades, we highlight the role of pH in adaptation to antifungal drug pressure. By acting on the PacC/Rim pathway, it may therefore be possible (i) to ensure fungal specificity and to limit the side effects of drugs, (ii) to ensure broad-spectrum efficacy, (iii) to attenuate fungal virulence, (iv) to obtain additive or synergistic effects with existing antifungal drugs through tolerance inhibition, and (v) to slow the emergence of resistant mutants.
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Alam MK, van Straaten KE, Sanders DAR, Kaminskyj SGW. Aspergillus nidulans cell wall composition and function change in response to hosting several Aspergillus fumigatus UDP-galactopyranose mutase activity mutants. PLoS One 2014; 9:e85735. [PMID: 24454924 PMCID: PMC3893270 DOI: 10.1371/journal.pone.0085735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/30/2013] [Indexed: 11/18/2022] Open
Abstract
Deletion or repression of Aspergillus nidulans ugmA (AnugmA), involved in galactofuranose biosynthesis, impairs growth and increases sensitivity to Caspofungin, a β-1,3-glucan synthesis antagonist. The A. fumigatus UgmA (AfUgmA) crystal structure has been determined. From that study, AfUgmA mutants with altered enzyme activity were transformed into AnugmA▵ to assess their effect on growth and wall composition in A. nidulans. The complemented (AnugmA::wild type AfugmA) strain had wild type phenotype, indicating these genes had functional homology. Consistent with in vitro studies, AfUgmA residues R182 and R327 were important for its function in vivo, with even conservative amino (RK) substitutions producing AnugmA? phenotype strains. Similarly, the conserved AfUgmA loop III histidine (H63) was important for Galf generation: the H63N strain had a partially rescued phenotype compared to AnugmA▵. Collectively, A. nidulans strains that hosted mutated AfUgmA constructs with low enzyme activity showed increased hyphal surface adhesion as assessed by binding fluorescent latex beads. Consistent with previous qPCR results, immunofluorescence and ELISA indicated that AnugmA▵ and AfugmA-mutated A. nidulans strains had increased α-glucan and decreased β-glucan in their cell walls compared to wild type and AfugmA-complemented strains. Like the AnugmA▵ strain, A. nidulans strains containing mutated AfugmA showed increased sensitivity to antifungal drugs, particularly Caspofungin. Reduced β-glucan content was correlated with increased Caspofungin sensitivity. Aspergillus nidulans wall Galf, α-glucan, and β-glucan content was correlated in A. nidulans hyphal walls, suggesting dynamic coordination between cell wall synthesis and cell wall integrity.
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Affiliation(s)
- Md Kausar Alam
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- * E-mail:
| | - Karin E. van Straaten
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - David A. R. Sanders
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Muñoz A, Harries E, Contreras-Valenzuela A, Carmona L, Read ND, Marcos JF. Two functional motifs define the interaction, internalization and toxicity of the cell-penetrating antifungal peptide PAF26 on fungal cells. PLoS One 2013; 8:e54813. [PMID: 23349973 PMCID: PMC3549957 DOI: 10.1371/journal.pone.0054813] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 12/17/2012] [Indexed: 11/19/2022] Open
Abstract
The synthetic, cell penetrating hexapeptide PAF26 (RKKWFW) is antifungal at low micromolar concentrations and has been proposed as a model for cationic, cell-penetrating antifungal peptides. Its short amino acid sequence facilitates the analysis of its structure-activity relationships using the fungal models Neurospora crassa and Saccharomyces cerevisiae, and human and plant pathogens Aspergillus fumigatus and Penicillium digitatum, respectively. Previously, PAF26 at low fungicidal concentrations was shown to be endocytically internalized, accumulated in vacuoles and then actively transported into the cytoplasm where it exerts its antifungal activity. In the present study, two PAF26 derivatives, PAF95 (AAAWFW) and PAF96 (RKKAAA), were designed to characterize the roles of the N-terminal cationic and the C-terminal hydrophobic motifs in PAF26's mode-of-action. PAF95 and PAF96 exhibited substantially reduced antifungal activity against all the fungi analyzed. PAF96 localized to fungal cell envelopes and was not internalized by the fungi. In contrast, PAF95 was taken up into vacuoles of N. crassa, wherein it accumulated and was trapped without toxic effects. Also, the PAF26 resistant Δarg1 strain of S. cerevisiae exhibited increased PAF26 accumulation in vacuoles. Live-cell imaging of GFP-labelled nuclei in A. fumigatus showed that transport of PAF26 from the vacuole to the cytoplasm was followed by nuclear breakdown and dissolution. This work demonstrates that the amphipathic PAF26 possesses two distinct motifs that allow three stages in its antifungal action to be defined: (i) its interaction with the cell envelope; (ii) its internalization and transport to vacuoles mediated by the aromatic hydrophobic domain; and (iii) its transport from vacuoles to the cytoplasm. Significantly, cationic residues in PAF26 are important not only for the electrostatic attraction and interaction with the fungal cell but also for transport from the vacuole to the cytoplasm, which coincides with cell death. Peptide containment within vacuoles preserves fungal cells from peptide toxicity.
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Affiliation(s)
- Alberto Muñoz
- Fungal Cell Biology Group, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Eleonora Harries
- Fungal Cell Biology Group, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- Department of Food Science, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | | | - Lourdes Carmona
- Department of Food Science, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
| | - Nick D. Read
- Fungal Cell Biology Group, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (JFM); (NDR)
| | - Jose F. Marcos
- Department of Food Science, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain
- * E-mail: (JFM); (NDR)
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18
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Muñoz A, Gandía M, Harries E, Carmona L, Read ND, Marcos JF. Understanding the mechanism of action of cell-penetrating antifungal peptides using the rationally designed hexapeptide PAF26 as a model. FUNGAL BIOL REV 2013. [DOI: 10.1016/j.fbr.2012.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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