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Hady RE, Fattouh N, Finianos M, Bitar I, Husni R, Khalaf R. Phenotypic and Genotypic Characterization of Candida parapsilosis complex isolates from a Lebanese Hospital. RESEARCH SQUARE 2024:rs.3.rs-4169036. [PMID: 38903078 PMCID: PMC11188110 DOI: 10.21203/rs.3.rs-4169036/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The opportunistic fungal pathogen Candida parapsilosis is a major causative agent of candidiasis leading to death in immunocompromised individuals. Azoles are the first line of defense in treatment by inhibiting ERG11, involved in the synthesis of ergosterol, the main sterol fungal sterol. Resistance to azoles is on the increase worldwide including in Lebanon. The purpose of this study is to characterize nine hospital isolates labeled as C. parapsilosis: four resistant and five sensitive to fluconazole. Phenotypic characterization was achieved through a battery of tests that target pathogenicity attributes such as virulence, biofilm formation, stress resistance, and ergosterol content. Genotypic analysis was done through whole genome sequencing to mutations in key virulence and resistance genes. Phylogenetic comparison was performed to determine strain relatedness and clonality. Genomic data and phylogenetic analysis revealed that three of the nine C. parapsilosis isolates were misidentified; two as C. orthopsilosis and C. metapsilosis belonging to the C. parapsilosis complex, while the third was C. albicans. Moreover, several known and novel mutations in key drug resistance and virulence genes were identified such as ERG11, ERG3, ERG6, CDR1, and FAS2. Phylogenetic analysis revealed a high degree of relatedness and clonality within our C. parapsilosis isolates. Our results showed that resistant isolates had no increased ergosterol content, no statistically significant difference in virulence, but exhibited an increase in biofilm content compared to the sensitive isolates. In conclusion, our study, the first of its kind in Lebanon, suggests several mechanisms of antifungal drug resistance in C. parapsilosis hospital isolates.
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Affiliation(s)
| | | | | | | | - Rola Husni
- Lebanese American University School of Medicine
| | - Roy Khalaf
- Lebanese American University - Byblos Campus
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Shree A, Pal S, Verma PK. Structural diversification of fungal cell wall in response to the stress signaling and remodeling during fungal pathogenesis. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2024; 30:733-747. [PMID: 38846457 PMCID: PMC11150350 DOI: 10.1007/s12298-024-01453-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 04/18/2024] [Accepted: 04/20/2024] [Indexed: 06/09/2024]
Abstract
Fungi are one of the most diverse organisms found in our surroundings. The heterotrophic lifestyle of fungi and the ever-changing external environmental factors pose numerous challenges for their survival. Despite all adversities, fungi continuously develop new survival strategies to secure nutrition and space from their host. During host-pathogen interaction, filamentous phytopathogens in particular, effectively infect their hosts by maintaining polarised growth at the tips of hyphae. The fungal cell wall, being the prime component of host contact, plays a crucial role in fortifying the intracellular environment against the harsh external environment. Structurally, the fungal cell wall is a highly dynamic yet rigid component, responsible for maintaining cellular morphology. Filamentous pathogens actively maintain their dynamic cell wall to compensate rapid growth on the host. Additionally, they secrete effectors to dampen the sophisticated mechanisms of plant defense and initiate various downstream signaling cascades to repair the damage inflicted by the host. Thus, the fungal cell wall serves as a key modulator of fungal pathogenicity. The fungal cell wall with their associated signaling mechanisms emerge as intriguing targets for host immunity. This review comprehensively examines and summarizes the multifaceted findings of various research groups regarding the dynamics of the cell wall in filamentous fungal pathogens during host invasion.
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Affiliation(s)
- Ankita Shree
- Plant Immunity Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Surabhi Pal
- Plant Immunity Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
| | - Praveen Kumar Verma
- Plant Immunity Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067 India
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Xu D, Wang M, Zhang X, Mao H, Xu H, Zhang B, Zeng X, Li F. The Putative Cytochrome b5 Domain-Containing Protein CaDap1 Homologue Is Involved in Antifungal Drug Tolerance, Cell Wall Chitin Maintenance, and Virulence in Candida albicans. J Fungi (Basel) 2024; 10:316. [PMID: 38786671 PMCID: PMC11122062 DOI: 10.3390/jof10050316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/18/2024] [Accepted: 04/19/2024] [Indexed: 05/25/2024] Open
Abstract
Candida albicans (Ca), a prominent opportunistic fungal pathogen in humans, has garnered considerable attention due to its infectious properties. Herein, we have identified and characterized CaCDAP1 (Ca orf19.1034), a homolog of ScDAP1 found in Saccharomyces cerevisiae. CaCDAP1 encodes a 183-amino acid protein with a conserved cytochrome b5-like heme-binding domain. The deletion of CaDAP1 renders Ca cells susceptible to caspofungin and terbinafine. CaDAP1 deletion confers resistance to Congo Red and Calcofluor White, and sensitivity to sodium dodecyl sulfate. The deletion of CaDAP1 results in a 50% reduction in chitin content within the cell wall, the downregulation of phosphorylation levels in CaMkc1, and the upregulation of phosphorylation levels in CaCek1. Notably, CaDAP1 deletion results in the abnormal hyphal development of Ca cells and diminishes virulence in a mouse systemic infection model. Thus, CaDAP1 emerges as a critical regulator governing cellular responses to antifungal drugs, the synthesis of cell wall chitin, and virulence in Ca.
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Affiliation(s)
- Dayong Xu
- College of Life Sciences, Huaibei Normal University, Huaibei 235000, China; (M.W.); (X.Z.); (H.M.); (H.X.); (B.Z.); (X.Z.)
| | | | | | | | | | | | | | - Feng Li
- College of Life Sciences, Huaibei Normal University, Huaibei 235000, China; (M.W.); (X.Z.); (H.M.); (H.X.); (B.Z.); (X.Z.)
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Cong H, Sun Y, Li C, Zhang Y, Wang Y, Ma D, Jiang J, Li L, Li L. The APSES transcription factor CfSwi6 is required for growth, cell wall integrity, and pathogenicity of Ceratocystis fimbriata. Microbiol Res 2024; 281:127624. [PMID: 38295680 DOI: 10.1016/j.micres.2024.127624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/29/2023] [Accepted: 01/15/2024] [Indexed: 02/16/2024]
Abstract
Cell wall integrity (CWI) is crucial for the growth, development, and host invasion of pathogenic fungi. The APSES transcription factor Swi6 in fungi plays a role in mediating cell wall integrity through the mitogen-activated protein kinase (MAPK) signaling pathway. Ceratocystis fimbriata is a notorious pathogenic fungus responsible for causing black rot in sweet potatoes. In this study, an orthologous APSES transcription factor Swi6 (CfSwi6) downstream of the CWI regulatory pathway in C. fimbriata was characterized. Deletion of CfSWI6 leads to impaired hyphal development, conidiation, and compromised cell wall integrity, resulting in a significant reduction in virulence. Transcriptome analysis revealed the involvement of CfSWI6 in various pathways, including the MAPK pathway, DNA synthesis and stress response. ChIP-seq data provided predictions of potential target genes regulated by CfSwi6. Through yeast one-hybrid, we confirmed the direct binding of CfSwi6 to the promoter of the chitin synthetase gene. In summary, these findings indicated that CfSwi6 plays an important role in the growth, development, and pathogenicity of C. fimbriata. This study provides new insights into the pathogenic mechanism of C. fimbriata in sweet potato and inspires potential strategies to control sweet potato black rot.
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Affiliation(s)
- Hao Cong
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Yong Sun
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Changgen Li
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Yongjing Zhang
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Yiming Wang
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Daifu Ma
- Chinese Academy of Agricultural Sciences Sweet Potato Research Institute, Xuzhou, Jiangsu 221131, China
| | - Jihong Jiang
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China
| | - Lianwei Li
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
| | - Ludan Li
- The Key Laboratory of Biotechnology for Medicinal and Edible Plant Resources of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
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Wagner AS, Lumsdaine SW, Mangrum MM, Reynolds TB. Caspofungin-induced β(1,3)-glucan exposure in Candida albicans is driven by increased chitin levels. mBio 2023; 14:e0007423. [PMID: 37377417 PMCID: PMC10470516 DOI: 10.1128/mbio.00074-23] [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: 01/09/2023] [Accepted: 05/04/2023] [Indexed: 06/29/2023] Open
Abstract
To successfully induce disease, Candida albicans must effectively evade the host immune system. One mechanism used by C. albicans to achieve this is to mask immunogenic β(1,3)-glucan epitopes within its cell wall under an outer layer of mannosylated glycoproteins. Consequently, induction of β(1,3)-glucan exposure (unmasking) via genetic or chemical manipulation increases fungal recognition by host immune cells in vitro and attenuates disease during systemic infection in mice. Treatment with the echinocandin caspofungin is one of the most potent drivers of β(1,3)-glucan exposure. Several reports using murine infection models suggest a role for the immune system, and specifically host β(1,3)-glucan receptors, in mediating the efficacy of echinocandin treatment in vivo. However, the mechanism by which caspofungin-induced unmasking occurs is not well understood. In this report, we show that foci of unmasking co-localize with areas of increased chitin within the yeast cell wall in response to caspofungin, and that inhibition of chitin synthesis via nikkomycin Z attenuates caspofungin-induced β(1,3)-glucan exposure. Furthermore, we find that both the calcineurin and Mkc1 mitogen-activated protein kinase pathways work synergistically to regulate β(1,3)-glucan exposure and chitin synthesis in response to drug treatment. When either of these pathways are interrupted, it results in a bimodal population of cells containing either high or low chitin content. Importantly, increased unmasking correlates with increased chitin content within these cells. Microscopy further indicates that caspofungin-induced unmasking correlates with actively growing cells. Collectively, our work presents a model in which chitin synthesis induces unmasking within the cell wall in response to caspofungin in growing cells. IMPORTANCE Systemic candidiasis has reported mortality rates ranging from 20% to 40%. The echinocandins, including caspofungin, are first-line antifungals used to treat systemic candidiasis. However, studies in mice have shown that echinocandin efficacy relies on both its cidal impacts on Candida albicans, as well as a functional immune system to successfully clear invading fungi. In addition to direct C. albicans killing, caspofungin increases exposure (unmasking) of immunogenic β(1,3)-glucan moieties. To evade immune detection, β(1,3)-glucan is normally masked within the C. albicans cell wall. Consequently, unmasked β(1,3)-glucan renders these cells more visible to the host immune system and attenuates disease progression. Therefore, discovery of how caspofungin-induced unmasking occurs is needed to elucidate how the drug facilitates host immune system-mediated clearance in vivo. We report a strong and consistent correlation between chitin deposition and unmasking in response to caspofungin and propose a model in which altered chitin synthesis drives increased unmasking during drug exposure.
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Affiliation(s)
- Andrew S. Wagner
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
| | | | - Mikayla M. Mangrum
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
| | - Todd B. Reynolds
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA
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Rahman S, van Rhijn N, Papastamoulis P, Thomson DD, Carter Z, Fortune-Grant R, Rattray M, Bromley MJ, Bignell E. Distinct Cohorts of Aspergillus fumigatus Transcription Factors Are Required for Epithelial Damage Occurring via Contact- or Soluble Effector-Mediated Mechanisms. Front Cell Infect Microbiol 2022; 12:907519. [PMID: 35982778 PMCID: PMC9379863 DOI: 10.3389/fcimb.2022.907519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/18/2022] [Indexed: 11/16/2022] Open
Abstract
Damage to the lung epithelium is a unifying feature of disease caused by the saprophytic fungus Aspergillus fumigatus. However, the mechanistic basis and the regulatory control of such damage is poorly characterized. Previous studies have identified A. fumigatus mediated pathogenesis as occurring at early (≤ 16 hours) or late (>16 hours) phases of the fungal interaction with epithelial cells, and respectively involve direct contact with the host cell or the action of soluble factors produced by mature fungal hyphae. Both early and late phases of epithelial damage have been shown to be subject to genetic regulation by the pH-responsive transcription factor PacC. This study sought to determine whether other transcriptional regulators play a role in modulating epithelial damage. In particular, whether the early and late phases of epithelial damage are governed by same or distinct regulators. Furthermore, whether processes such as spore uptake and hyphal adhesion, that have previously been documented to promote epithelial damage, are governed by the same cohorts of epithelial regulators. Using 479 strains from the recently constructed library of A. fumigatus transcription factor null mutants, two high-throughput screens assessing epithelial cell detachment and epithelial cell lysis were conducted. A total of 17 transcription factor mutants were found to exhibit reproducible deficits in epithelial damage causation. Of these, 10 mutants were defective in causing early phase damage via epithelial detachment and 8 mutants were defective in causing late phase damage via epithelial lysis. Remarkably only one transcription factor, PacC, was required for causation of both phases of epithelial damage. The 17 mutants exhibited varied and often unique phenotypic profiles with respect to fitness, epithelial adhesion, cell wall defects, and rates of spore uptake by epithelial cells. Strikingly, 9 out of 10 mutants deficient in causing early phase damage also exhibited reduced rates of hyphal extension, and culture supernatants of 7 out of 8 mutants deficient in late phase damage were significantly less cytotoxic. Our study delivers the first high-level overview of A. fumigatus regulatory genes governing lung epithelial damage, suggesting highly coordinated genetic orchestration of host-damaging activities that govern epithelial damage in both space and time.
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Affiliation(s)
- Sayema Rahman
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Norman van Rhijn
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | | | - Darren D Thomson
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- MRC Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Zorana Carter
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Rachael Fortune-Grant
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Magnus Rattray
- Division of Informatics, School of Heath Sciences, University of Manchester, Manchester, United Kingdom
| | - Michael John Bromley
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Elaine Bignell
- Manchester Fungal Infection Group, Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- MRC Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
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Chitin Synthase Genes Are Differentially Required for Growth, Stress Response, and Virulence in Verticillium dahliae. J Fungi (Basel) 2022; 8:jof8070681. [PMID: 35887437 PMCID: PMC9320267 DOI: 10.3390/jof8070681] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/17/2022] [Accepted: 06/27/2022] [Indexed: 11/17/2022] Open
Abstract
Crop wilt disease caused by Verticillium dahliae usually leads to serious yield loss. Chitin, an important component of most fungal cell walls, functions to maintain the rigidity of cell walls and septa. Chitin synthesis mainly relies on the activity of chitin synthase (CHS). Eight CHS genes have been predicted in V. dahliae. In this study, we characterized the functions of these genes in terms of growth, stress responses, penetration, and virulence. Results showed that VdCHS5 is important for conidia germination and resistance to hyperosmotic stress. Conidial production is significantly decreased in Vdchs1, Vdchs4, and Vdchs8 mutants. VdCHS1, VdCHS2, VdCHS4, VdCHS6, VdCHS7, and VdCHS8 genes are important for cell wall integrity, while all mutants are important for cell membrane integrity. All of the VdCHS genes, except for VdCHS3, are required for the full pathogenicity of V. dahliae to Arabidopsis thaliana and cotton plants. The in vitro and in vivo penetration of Vdchs1, Vdchs4, Vdchs6, and Vdchs7 mutants was impaired, while that of the other mutants was normal. Overall, our results indicate that the VdCHS genes exert diverse functions to regulate the growth and development, conidial germination, conidial production, stress response, penetration, and virulence in V. dahliae.
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Zhen C, Lu H, Jiang Y. Novel Promising Antifungal Target Proteins for Conquering Invasive Fungal Infections. Front Microbiol 2022; 13:911322. [PMID: 35783432 PMCID: PMC9243655 DOI: 10.3389/fmicb.2022.911322] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 05/24/2022] [Indexed: 11/26/2022] Open
Abstract
Invasive fungal infections (IFIs) pose a serious clinical problem, but the antifungal arsenal is limited and has many disadvantages, such as drug resistance and toxicity. Hence, there is an urgent need to develop antifungal compounds that target novel target proteins of pathogenic fungi for treating IFIs. This review provides a comprehensive summary of the biological functions of novel promising target proteins for treating IFIs in pathogenic fungi and their inhibitors. Inhibitors of inositol phosphoramide (IPC) synthases (such as Aureobasidin A, Khafrefungin, Galbonolide A, and Pleofungin A) have potent antifungal activities by inhibiting sphingolipid synthesis. Disrupting glycosylphosphatidylinositol (GPI) biosynthesis by Jawsamycin (an inhibitor of Spt14), M720 (an inhibitor of Mcd4), and APX001A (an inhibitor of Gwt1) is a promising strategy for treating IFIs. Turbinmicin is a natural-compound inhibitor of Sec14 and has extraordinary antifungal efficacy, broad-antifungal spectrum, low toxicity, and is a promising new compound for treating IFIs. CMLD013075 targets fungal heat shock protein 90 (Hsp90) and has remarkable antifungal efficacy. Olorofim, as an inhibitor of dihydrolactate dehydrogenase, is a breakthrough drug treatment for IFIs. These novel target proteins and their inhibitors may overcome the limitations of currently available antifungal drugs and improve patient outcomes in the treatment of IFIs.
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Khona DK, Roy S, Ghatak S, Huang K, Jagdale G, Baker LA, Sen CK. Ketoconazole resistant Candida albicans is sensitive to a wireless electroceutical wound care dressing. Bioelectrochemistry 2021; 142:107921. [PMID: 34419917 PMCID: PMC8788813 DOI: 10.1016/j.bioelechem.2021.107921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/27/2021] [Accepted: 07/31/2021] [Indexed: 01/22/2023]
Abstract
Wireless electroceutical dressing (WED) fabric kills bacteria and disrupts bacterial biofilm. This work tested, comparing with standard of care topical antibiotic ketoconazole, whether the weak electric field generated by WED is effective to manage infection caused by ketoconazole-resistant yeast Candida albicans. WED inhibited Candida albicans biofilm formation and planktonic growth. Unlike ketoconazole, WED inhibited yeast to hyphal transition and downregulated EAP1 curbing cell attachment. In response to WED-dependent down-regulation of biofilm-forming BRG1 and ROB1, BCR1 expression was markedly induced in what seems to be a futile compensatory response. WED induced NRG1 and TUP1, negative regulators of filamentation; it down-regulated EFG1, a positive regulator of hyphal pathway. Consistent with the anti-hyphal properties of WED, the expression of ALS3 and HWP1 were diminished. Ketoconazole failed to reproduce the effects of WED on NRG1, TUP1 and EFG1. WED blunted efflux pump activity; this effect was in direct contrast to that of ketoconazole. WED exposure compromised cellular metabolism. In the presence of ketoconazole, the effect was synergistic. Unlike ketoconazole, WED caused membrane depolarization, changes in cell wall composition and loss of membrane integrity. This work presents first evidence that weak electric field is useful in managing pathogens which are otherwise known to be antibiotic resistant.
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Affiliation(s)
- Dolly K Khona
- Indiana Center for Regenerative Medicine & Engineering, Indiana University Health Comprehensive Wound Center, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Sashwati Roy
- Indiana Center for Regenerative Medicine & Engineering, Indiana University Health Comprehensive Wound Center, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Subhadip Ghatak
- Indiana Center for Regenerative Medicine & Engineering, Indiana University Health Comprehensive Wound Center, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Kaixiang Huang
- Department of Chemistry, Indiana University, Bloomington, IN 47405, United States
| | - Gargi Jagdale
- Department of Chemistry, Indiana University, Bloomington, IN 47405, United States
| | - Lane A Baker
- Department of Chemistry, Indiana University, Bloomington, IN 47405, United States
| | - Chandan K Sen
- Indiana Center for Regenerative Medicine & Engineering, Indiana University Health Comprehensive Wound Center, Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
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Mela A, Momany M. Septins coordinate cell wall integrity and lipid metabolism in a sphingolipid-dependent process. J Cell Sci 2021; 135:256543. [PMID: 33912961 DOI: 10.1242/jcs.258336] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 12/31/2020] [Indexed: 01/09/2023] Open
Abstract
Septins colocalize with membrane sterol-rich regions and facilitate recruitment of cell wall synthases during wall remodeling. We show that null mutants missing an Aspergillus nidulans core septin present in hexamers and octamers (ΔaspAcdc11, ΔaspBcdc3 or ΔaspCcdc12) are sensitive to multiple cell wall-disturbing agents that activate the cell wall integrity MAPK pathway. The null mutant missing the octamer-exclusive core septin (ΔaspDcdc10) showed similar sensitivity, but only to a single cell wall-disturbing agent and the null mutant missing the noncore septin (ΔaspE) showed only very mild sensitivity to a different single agent. Core septin mutants showed changes in wall polysaccharide composition and chitin synthase localization. Mutants missing any of the five septins resisted ergosterol-disrupting agents. Hexamer mutants showed increased sensitivity to sphingolipid-disrupting agents. Core septins mislocalized after treatment with sphingolipid-disrupting agents, but not after ergosterol-disrupting agents. Our data suggest that the core septins are involved in cell wall integrity signaling, that all five septins are involved in monitoring ergosterol metabolism, that the hexamer septins are required for sphingolipid metabolism and that septins require sphingolipids to coordinate the cell wall integrity response.
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Affiliation(s)
- Alexander Mela
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
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Tamez-Castrellón AK, Romeo O, García-Carnero LC, Lozoya-Pérez NE, Mora-Montes HM. Virulence Factors in Sporothrix schenckii, One of the Causative Agents of Sporotrichosis. Curr Protein Pept Sci 2021; 21:295-312. [PMID: 31589121 DOI: 10.2174/1389203720666191007103004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 08/02/2019] [Accepted: 08/08/2019] [Indexed: 11/22/2022]
Abstract
Sporothrix schenckii is one of the etiological agents of sporotrichosis, a fungal infection distributed worldwide. Both, the causative organism and the disease have currently received limited attention by the medical mycology community, most likely because of the low mortality rates associated with it. Nonetheless, morbidity is high in endemic regions and the versatility of S. schenckii to cause zoonosis and sapronosis has attracted attention. Thus far, virulence factors associated with this organism are poorly described. Here, comparing the S. schenckii genome sequence with other medically relevant fungi, genes involved in morphological change, cell wall synthesis, immune evasion, thermotolerance, adhesion, biofilm formation, melanin production, nutrient uptake, response to stress, extracellular vesicle formation, and toxin production are predicted and discussed as putative virulence factors in S. schenckii.
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Affiliation(s)
- Alma K Tamez-Castrellón
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Orazio Romeo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Laura C García-Carnero
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Nancy E Lozoya-Pérez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
| | - Héctor M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, C.P. 36050, Guanajuato, Gto., Mexico
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12
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Lenardon MD, Sood P, Dorfmueller HC, Brown AJ, Gow NA. Scalar nanostructure of the Candida albicans cell wall; a molecular, cellular and ultrastructural analysis and interpretation. Cell Surf 2020; 6:100047. [PMID: 33294751 PMCID: PMC7691183 DOI: 10.1016/j.tcsw.2020.100047] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/16/2022] Open
Abstract
Despite the importance of fungal cell walls as the principle determinant of fungal morphology and the defining element determining fungal interactions with other cells, few scalar models have been developed that reconcile chemical and microscopic attributes of its structure. The cell wall of the fungal pathogen Candida albicans is comprised of an amorphous inner skeletal layer of β(1,3)- and β(1,6)-glucan and chitin and an outer fibrillar layer thought to be dominated by highly mannosylated cell wall proteins. The architecture of these two layers can be resolved at the electron microscopy level, but the visualised structure of the wall has not yet been defined precisely in chemical terms. We have therefore examined the precise structure, location and molecular sizes of the cell wall components using transmission electron microscopy and tomography and tested predictions of the cell wall models using mutants and agents that perturb the normal cell wall structure. We demonstrate that the fibrils are comprised of a frond of N-linked outer chain mannans linked to a basal layer of GPI-proteins concentrated in the mid-wall region and that the non-elastic chitin microfibrils are cantilevered with sufficient lengths of non-fibrillar chitin and/or β-glucan to enable the chitin-glucan cage to flex, e.g. during morphogenesis and osmotic swelling. We present the first three-dimensional nano-scalar model of the C. albicans cell wall which can be used to test hypotheses relating to the structure-function relationships that underpin the pathobiology of this fungal pathogen.
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Key Words
- 2D, two dimensions
- 2°, secondary
- 3D, three dimensions
- 3°, tertiary
- 6xHis, hexahistidine tag
- AFM, atomic force microscopy
- BSA, bovine serum albumin
- CWPs, cell wall proteins
- Cell wall proteins
- ChBD, chitin binding domain
- Chitin
- EndoH, endoglycosidase H
- Fc-dectin-1, soluble chimeric form of dectin-1
- Fungal cell wall ultrastructure
- GPI, glycosylphosphatidylinositol
- HPF/FS, high pressure freezing/freeze substitution
- HuCκ, human kappa light chain
- N-mannan
- NMR, nuclear magnetic resonance
- OD600, optical density at 600 nm
- PAMPs, pathogen associated molecular patterns
- PBS, phosphate buffered saline
- PRRs, pattern recognition receptors
- SEM, scanning electron microscopy
- TEM, transmission electron microscopy
- WGA, wheat germ agglutinin
- rpm, revolutions per minute
- scAb, single chain antibody
- β-glucan
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Affiliation(s)
- Megan D. Lenardon
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Prashant Sood
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Helge C. Dorfmueller
- Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
| | - Alistair J.P. Brown
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Neil A.R. Gow
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
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13
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Gonçales RA, Ricci-Azevedo R, Vieira VCS, Fernandes FF, Thomaz SMDO, Carvalho A, Vendruscolo PE, Cunha C, Roque-Barreira MC, Rodrigues F. Paracoccin Overexpression in Paracoccidioides brasiliensis Enhances Fungal Virulence by Remodeling Chitin Properties of the Cell Wall. J Infect Dis 2020; 224:164-174. [PMID: 33201217 DOI: 10.1093/infdis/jiaa707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 11/12/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The thermodimorphic fungi Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis. Although poorly studied, paracoccin (PCN) from Paracoccidioides brasiliensis has been shown to harbor lectinic, enzymatic, and immunomodulatory properties that affect disease development. METHODS Mutants of P. brasiliensis overexpressing PCN (ov-PCN) were constructed by Agrobacterium tumefaciens-mediated transformation. ov-PCN strains were analyzed and inoculated intranasally or intravenously to mice. Fungal burden, lung pathology, and survival were monitored to evaluate virulence. Electron microscopy was used to evaluate the size of chito-oligomer particles released by ov-PCN or wild-type strains to growth media. RESULTS ov-PCN strains revealed no differences in cell growth and viability, although PCN overexpression favored cell separation, chitin processing that results in the release of smaller chito-oligomer particles, and enhanced virulence. Our data show that PCN triggers a critical effect in the cell wall biogenesis through the chitinase activity resulting from overexpression of PCN. As such, PCN overexpression aggravates the disease caused by P. brasiliensis. CONCLUSIONS Our data are consistent with a model in which PCN modulates the cell wall architecture via its chitinase activity. These findings highlight the potential for exploiting PCN function in future therapeutic approaches.
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Affiliation(s)
- Relber Aguiar Gonçales
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil.,Life and Health Sciences Research Institute School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rafael Ricci-Azevedo
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil
| | - Vanessa C S Vieira
- Life and Health Sciences Research Institute School of Medicine, University of Minho, Braga, Portugal
| | - Fabrício F Fernandes
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil
| | - Sandra M de O Thomaz
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil
| | - Agostinho Carvalho
- Life and Health Sciences Research Institute School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Patrícia E Vendruscolo
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil
| | - Cristina Cunha
- Life and Health Sciences Research Institute School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Maria Cristina Roque-Barreira
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto/São Paulo, Brazil
| | - Fernando Rodrigues
- Life and Health Sciences Research Institute School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
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14
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Henriques BS, Garcia ES, Azambuja P, Genta FA. Determination of Chitin Content in Insects: An Alternate Method Based on Calcofluor Staining. Front Physiol 2020; 11:117. [PMID: 32132935 PMCID: PMC7040371 DOI: 10.3389/fphys.2020.00117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/31/2020] [Indexed: 11/26/2022] Open
Abstract
Chitin is an aminopolysaccharide present in yeast cells and arthropod cuticle and is one of the most abundant biopolymers. The conventional methods for the quantitation of chitin content in biological samples are based on its hydrolysis (acid or enzymatic), and the assessment of the byproduct, glucosamine. However, previously described methodologies are time-consuming, laborious, low throughput, and not applicable to insect samples in many cases. Here we describe a new approach to chitin content quantitation based on calcofluor fluorescent brightener staining of samples, followed by microplate fluorescence readings. Calcofluor is a specific chitin stain commonly used for topological localization of the polymer. The protocol was tested in three important disease vector species, namely Lutzomyia longipalpis, Aedes aegypti, and Rhodnius prolixus, and then compared to a classic colorimetric chitin assessment method. Results show that chitin content in the tested insects can vary largely in a range of 8–4600 micrograms of chitin per insect, depending on species, sex, and instar. Comparisons between measurements from the previous protocol and calcofluor method showed statistically significant differences in some samples. However, the difference might be due to interference in the classic method from non-chitin sources of glucosamine and reducing agents. Furthermore, chitinase hydrolysis reduces the total chitin mass estimated between 36 and 74%, consolidating the fluorescent measurements as actual stained chitin in the same extent that was observed with the standard protocol. Therefore, the calcofluor staining method revealed to be a fast and reliable technique for chitin quantitation in homogenized insect samples.
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Affiliation(s)
- Bianca Santos Henriques
- Laboratory of Insect Physiology and Biochemistry, Oswaldo Cruz Institute - Oswaldo Cruz Foundation (IOC-FIOCRUZ), Rio de Janeiro, Brazil
| | - Eloi Souza Garcia
- Laboratory of Insect Physiology and Biochemistry, Oswaldo Cruz Institute - Oswaldo Cruz Foundation (IOC-FIOCRUZ), Rio de Janeiro, Brazil.,National Institute of Science and Technology for Molecular Entomology (INCT-EM), Cidade Universitária, Rio de Janeiro, Brazil
| | - Patricia Azambuja
- Laboratory of Insect Physiology and Biochemistry, Oswaldo Cruz Institute - Oswaldo Cruz Foundation (IOC-FIOCRUZ), Rio de Janeiro, Brazil
| | - Fernando Ariel Genta
- Laboratory of Insect Physiology and Biochemistry, Oswaldo Cruz Institute - Oswaldo Cruz Foundation (IOC-FIOCRUZ), Rio de Janeiro, Brazil.,National Institute of Science and Technology for Molecular Entomology (INCT-EM), Cidade Universitária, Rio de Janeiro, Brazil
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15
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Garcia-Rubio R, de Oliveira HC, Rivera J, Trevijano-Contador N. The Fungal Cell Wall: Candida, Cryptococcus, and Aspergillus Species. Front Microbiol 2020; 10:2993. [PMID: 31993032 PMCID: PMC6962315 DOI: 10.3389/fmicb.2019.02993] [Citation(s) in RCA: 362] [Impact Index Per Article: 90.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/10/2019] [Indexed: 01/23/2023] Open
Abstract
The fungal cell wall is located outside the plasma membrane and is the cell compartment that mediates all the relationships of the cell with the environment. It protects the contents of the cell, gives rigidity and defines the cellular structure. The cell wall is a skeleton with high plasticity that protects the cell from different stresses, among which osmotic changes stand out. The cell wall allows interaction with the external environment since some of its proteins are adhesins and receptors. Since, some components have a high immunogenic capacity, certain wall components can drive the host's immune response to promote fungus growth and dissemination. The cell wall is a characteristic structure of fungi and is composed mainly of glucans, chitin and glycoproteins. As the components of the fungal cell wall are not present in humans, this structure is an excellent target for antifungal therapy. In this article, we review recent data on the composition and synthesis, influence of the components of the cell wall in fungi-host interaction and the role as a target for the next generation of antifungal drugs in yeasts (Candida and Cryptococcus) and filamentous fungi (Aspergillus).
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Affiliation(s)
- Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | | | - Johanna Rivera
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
| | - Nuria Trevijano-Contador
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
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16
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Rzeszutek E, Díaz-Moreno SM, Bulone V. Identification and Characterization of the Chitin Synthase Genes From the Fish Pathogen Saprolegnia parasitica. Front Microbiol 2019; 10:2873. [PMID: 31921051 PMCID: PMC6923183 DOI: 10.3389/fmicb.2019.02873] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/28/2019] [Indexed: 01/14/2023] Open
Abstract
Saprolegnia parasitica is a pathogenic oomycete responsible for severe fish infections. Despite its low abundance in the cell wall of S. parasitica, chitin is essential for hyphal growth as the inhibition of its biosynthesis leads to highly reduced growth. Here we identified and characterized chitin synthases (CHS) from S. parasitica as potential targets for anti-oomycete drugs. Bioinformatics analyses allowed the identification of six different putative Chs genes in the genome of the pathogen. The total number of genes was confirmed by Southern blot analysis and their expression levels were determined by quantitative PCR. Four of the six Chs genes were expressed in the mycelium, while the two others exhibited undetectable levels of expression. The mycelium was highly sensitive to the addition of nikkomycin Z (NZ) in the culture medium, which led to a decreased amount of chitin in the cell wall by up to 40% in the conditions tested, and to the formation of abnormal branching structures in the hyphae. The presence of NZ increased the expression level of one of the genes, Chs3, suggesting that the corresponding product is compensating the disruption of chitin biosynthesis in the hyphae. In addition, the activity of isolated CHS was strongly inhibited by NZ in vitro. Altogether our data indicate the importance of CHS for the vegetative growth of S. parasitica and demonstrate that these enzymes represent promising targets for the control of diseases caused by oomycetes.
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Affiliation(s)
- Elzbieta Rzeszutek
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Sara M Díaz-Moreno
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Vincent Bulone
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden.,ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, The University of Adelaide, Urrbrae, SA, Australia
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17
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Degani G, Popolo L. The Glucan-Remodeling Enzyme Phr1p and the Chitin Synthase Chs1p Cooperate to Maintain Proper Nuclear Segregation and Cell Integrity in Candida albicans. Front Cell Infect Microbiol 2019; 9:400. [PMID: 31824871 PMCID: PMC6882867 DOI: 10.3389/fcimb.2019.00400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/07/2019] [Indexed: 11/13/2022] Open
Abstract
GH72 family of β-(1,3)-glucanosyltransferases is unique to fungi and is required for cell wall biogenesis, morphogenesis, virulence, and in some species is essential for life. Candida albicans PHR1 and PHR2 are pH-regulated genes that encode GH72 enzymes highly similar to Gas1p of Saccharomyces cerevisiae. PHR1 is expressed at pH ≥ 5.5 while PHR2 is transcribed at pH ≤ 5.5. Both are essential for C. albicans morphogenesis and virulence. During growth at neutral-alkaline pH, Phr1p-GFP preferentially localizes to sites of active cell wall formation as the incipient bud, the mother-daughter neck, the bud periphery, and concentrates in the septum at cytokinesis. We further investigated this latter localization. In chs3Δ cells, lacking the chitin of the chitin ring and lateral cell wall, Phr1p-GFP still concentrated along the thin line of the primary septum formed by chitin deposited by chitin synthase I (whose catalytic subunit is Chs1p) suggesting that it plays a role during formation of the secondary septa. RO-09-3143, a highly specific inhibitor of Chs1p activity, inhibits septum formation and blocks cell division. However, alternative septa are produced and are crucial for cell survival. Phr1p-GFP is excluded from such aberrant septa. Finally, we determined the effects of RO-09-3143 in cells lacking Phr1p. PHR1 null mutant was more susceptible to the drug than the wild type. The phr1Δ cells were larger, devoid of septa, and underwent endomitosis and cell death. Phr1p and Chs1p cooperate in maintaining cell integrity and in coupling morphogenesis with nuclear division in C. albicans.
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Affiliation(s)
- Genny Degani
- Department of Biosciences, University of Milan, Milan, Italy
| | - Laura Popolo
- Department of Biosciences, University of Milan, Milan, Italy
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18
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Oliveira-Brito PKM, Rezende CP, Almeida F, Roque-Barreira MC, da Silva TA. iNOS/Arginase-1 expression in the pulmonary tissue over time during Cryptococcus gattii infection. Innate Immun 2019; 26:117-129. [PMID: 31446837 PMCID: PMC7016403 DOI: 10.1177/1753425919869436] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inhalation of Cryptococcus gattii yeasts (causing cryptococcosis) triggers an anti-cryptococcal immune response initiated by macrophages, neutrophils or dendritic cells, and the iNOS expressed by various cells may regulate the function and differentiation of innate and adaptive immune cells. Here, we evaluated the effect of progression of C. gattii infection on the host innate immune response. C. gattii infection in BALB/c mice spreads to several organs by 21 d post infection. The numbers of neutrophils and lymphocytes in the peripheral blood of C. gattii–infected mice were remarkably altered on that day. The frequency of CD11b+ cells and cell concentrations of CD4+ and CD8+ T cells was significantly altered in the pulmonary tissue of infected mice. We found a higher frequency of CD11b+/iNOS+ cells in the lungs of infected mice, accompanied by an increase in frequency of CD11b+/Arginase-1+ cells over time. Moreover, the iNOS/Arginase-1 expression ratio in CD11b+ cells reached its lowest value at 21 d post infection. In addition, the cytokine micro-environment in infected lungs did not show a pro-inflammatory profile. Surprisingly, iNOS knock-out prolonged the survival of infected mice, while their pulmonary fungal burden was higher than that of infected WT mice. Thus, C. gattii infection alters the immune response in the pulmonary tissue, and iNOS expression may play a key role in infection progression.
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Affiliation(s)
- Patrícia Kellen Martins Oliveira-Brito
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Brazil.,These authors contributed equally to this work
| | - Caroline Patini Rezende
- Department of Biochemistry and Immunology, Ribeirao Preto Medical School, University of São Paulo, Brazil.,These authors contributed equally to this work
| | - Fausto Almeida
- Department of Biochemistry and Immunology, Ribeirao Preto Medical School, University of São Paulo, Brazil
| | - Maria Cristina Roque-Barreira
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Brazil
| | - Thiago Aparecido da Silva
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Brazil
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19
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Targeting the fungal cell wall: current therapies and implications for development of alternative antifungal agents. Future Med Chem 2019; 11:869-883. [PMID: 30994368 DOI: 10.4155/fmc-2018-0465] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Fungal infections are a worldwide problem associated with high morbidity and mortality. There are relatively few antifungal agents, and resistance has emerged within these pathogens for the newest antifungal drugs. As the fungal cell wall is critical for growth and development, it is one of the most important targets for drug development. In this review, the currently available cell wall inhibitors and suitable drug candidates for the treatment of fungal infections are explored. Future studies of the fungal cell wall and compounds that have detrimental effects on this important outer structural layer could aid in antifungal drug discovery and lead to the development of alternative cell wall inhibitors to fill gaps in clinical therapies for difficult-to-treat fungal infections.
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20
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AP-2-Dependent Endocytic Recycling of the Chitin Synthase Chs3 Regulates Polarized Growth in Candida albicans. mBio 2019; 10:mBio.02421-18. [PMID: 30890602 PMCID: PMC6426607 DOI: 10.1128/mbio.02421-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The human fungal pathogen Candida albicans is known to require endocytosis to enable its adaptation to diverse niches and to maintain its highly polarized hyphal growth phase. While studies have identified changes in transcription leading to the synthesis and secretion of new proteins to facilitate hyphal growth, effective maintenance of hyphae also requires concomitant removal or relocalization of other cell surface molecules. The key molecules which must be removed from the cell surface, and the mechanisms behind this, have, however, remained elusive. In this study, we show that the AP-2 endocytic adaptor complex is required for the internalization of the major cell wall biosynthesis enzyme Chs3. We demonstrate that this interaction is mediated by the AP-2 mu subunit (Apm4) YXXΦ binding domain. We also show that in the absence of Chs3 recycling via AP-2, cells have abnormal cell wall composition, defective polarized cell wall deposition, and morphological defects. The study also highlights key distinctions between endocytic requirements of growth at yeast buds compared to that at hyphal tips and different requirements of AP-2 in maintaining the polarity of mannosylated proteins and ergosterol at hyphal tips. Together, our findings highlight the importance of correct cell wall deposition in cell shape maintenance and polarized growth and the key regulatory role of endocytic recycling via the AP-2 complex.IMPORTANCE Candida albicans is a human commensal yeast that can cause significant morbidity and mortality in immunocompromised individuals. Within humans, C. albicans can adopt different morphologies as yeast or filamentous hyphae and can occupy different niches with distinct temperatures, pHs, CO2 levels, and nutrient availability. Both morphological switching and growth in different environments require cell surface remodelling, which involves both the addition of newly synthesized proteins as well as the removal of other proteins. In our study, we demonstrate the importance of an adaptor complex AP-2 in internalizing and recycling a specific cell surface enzyme to maintain effective polarized hyphal growth. Defects in formation of the complex or in its ability to interact directly with cargo inhibit enzyme uptake and lead to defective cell walls and aberrant hyphal morphology. Our data indicate that the AP-2 adaptor plays a central role in regulating cell surface composition in Candida.
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21
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Brown HE, Esher SK, Alspaugh JA. Chitin: A "Hidden Figure" in the Fungal Cell Wall. Curr Top Microbiol Immunol 2019; 425:83-111. [PMID: 31807896 DOI: 10.1007/82_2019_184] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chitin and chitosan are two related polysaccharides that provide important structural stability to fungal cell walls. Often embedded deeply within the cell wall structure, these molecules anchor other components at the cell surface. Chitin-directed organization of the cell wall layers allows the fungal cell to effectively monitor and interact with the external environment. For fungal pathogens, this interaction includes maintaining cellular strategies to avoid excessive detection by the host innate immune system. In turn, mammalian and plant hosts have developed their own strategies to process fungal chitin, resulting in chitin fragments of varying molecular size. The size-dependent differences in the immune activation behaviors of variably sized chitin molecules help to explain how chitin and related chitooligomers can both inhibit and activate host immunity. Moreover, chitin and chitosan have recently been exploited for many biomedical applications, including targeted drug delivery and vaccine development.
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Affiliation(s)
- Hannah E Brown
- Department of Medicine, Department of Molecular Genetics and Microbiology, Duke University School of Medicine, 303 Sands Research Building, DUMC, 102359, Durham, 27710, NC, USA
| | - Shannon K Esher
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, USA
| | - J Andrew Alspaugh
- Department of Medicine, Department of Molecular Genetics and Microbiology, Duke University School of Medicine, 303 Sands Research Building, DUMC, 102359, Durham, 27710, NC, USA.
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22
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Lee KK, Kubo K, Abdelaziz JA, Cunningham I, de Silva Dantas A, Chen X, Okada H, Ohya Y, Gow NAR. Yeast species-specific, differential inhibition of β-1,3-glucan synthesis by poacic acid and caspofungin. Cell Surf 2018; 3:12-25. [PMID: 30370375 PMCID: PMC6195761 DOI: 10.1016/j.tcsw.2018.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 08/16/2018] [Accepted: 09/04/2018] [Indexed: 01/27/2023] Open
Abstract
Poacic acid antifungal activity is both strains and species dependent for a range of Candida species. The calcineurin pathway regulates poacic acid sensitivity in C. albicans. Point mutations in β-1,3-glucan synthase Fks1 differentially affect poacic acid and echinocandin sensitivity.
The rise of widespread antifungal resistance fuels the need to explore new classes of inhibitory molecules as potential novel inhibitors. Recently a plant natural product poacic acid (PA) was shown to inhibit β-1,3-glucan synthesis, and to have antifungal activity against a range of plant pathogens and against Saccharomyces cerevisiae. As with the echinocandins, such as caspofungin, PA targets the synthesis of cell wall β-1,3-glucan and has potential utility in the treatment of medically important fungi. However, the antifungal activity of PA against human pathogenic Candida species has not been explored and the precise mode of action of this compound is not understood. Here, we show that PA sensitivity is regulated by the calcineurin pathway and that susceptibility to PA varied significantly between Candida species, but did not correlate with in vitro β-glucan synthase activity, cell wall β-glucan content or the sensitivity of the species to caspofungin. Strains with point mutations (S645Y or S645P) in the hotspot1 region of the β-1,3-glucan synthase subunit Fks1, had decreased sensitivity to caspofungin but increased sensitivity to PA. C. guilliermondii, C. orthopsilosis, and C. parapsilosis were more sensitive to PA than C. albicans, C. dubliniensis, C. tropicalis, and C. glabrata. These observations suggest that there are significant differences in the mode of action of PA and caspofungin and that PA or PA analogues are not likely to have broad spectrum activity in the treatment of Candida infections.
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Affiliation(s)
- Keunsook K Lee
- The Aberdeen Fungal Group, MRC Centre for Medical Mycology, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Karen Kubo
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.,AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, Chiba, 277-8565, Japan
| | - Jehan Abdelmoneim Abdelaziz
- The Aberdeen Fungal Group, MRC Centre for Medical Mycology, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Iain Cunningham
- The Aberdeen Fungal Group, MRC Centre for Medical Mycology, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Alessandra de Silva Dantas
- The Aberdeen Fungal Group, MRC Centre for Medical Mycology, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Xiaolin Chen
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan
| | - Hiroki Okada
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan
| | - Yoshikazu Ohya
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.,AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, Chiba, 277-8565, Japan
| | - Neil A R Gow
- The Aberdeen Fungal Group, MRC Centre for Medical Mycology, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
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Remodeling of the Candida glabrata cell wall in the gastrointestinal tract affects the gut microbiota and the immune response. Sci Rep 2018; 8:3316. [PMID: 29463799 PMCID: PMC5820338 DOI: 10.1038/s41598-018-21422-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/02/2018] [Indexed: 12/17/2022] Open
Abstract
The gastrointestinal (GI) microbiota acts a natural barrier to the proliferation of opportunistic pathogens. Candida glabrata is an opportunistic yeast pathogen that has adapted to colonize all segments of the human GI tract. We observed an increase in Escherichia coli, Enterococcus faecalis, and Bacteroides vulgatus populations, and a decrease in Lactobacillus johnsonii, Bacteroides thetaiotaomicron, and Bifidobacterium animalis in mice with DSS-induced colitis. This reduction was more pronounced for L. johnsonii during C. glabrata overgrowth. In addition, C. glabrata overgrowth increased mouse mortality and inflammatory parameters, and modulated the expression of intestinal receptors and signaling pathways. The C. glabrata cell wall underwent various changes during the course of C. glabrata colonization, and showed a significant increase in chitin. C. glabrata deficient in chitin synthase-3 induced fewer inflammatory parameters than the parental strain during intestinal inflammation. Oral administration of chitin attenuated the impact of colitis, and reduced the number of aerobic bacteria and C. glabrata overgrowth, while chitinase-3-like protein-1 increased. This study provides evidence that inflammation of the gut alters the microbial balance and leads to C. glabrata cell wall remodeling through an increase in chitin, which is involved in promoting persistence of C. glabrata in the gut.
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24
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Targeting Candida spp. to develop antifungal agents. Drug Discov Today 2018; 23:802-814. [PMID: 29353694 DOI: 10.1016/j.drudis.2018.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 12/09/2017] [Accepted: 01/04/2018] [Indexed: 01/15/2023]
Abstract
Invasive fungal infections are a complex challenge throughout the world because of their high incidence, mainly in critically ill patients, and high mortality rates. The antifungal agents currently available are limited; thus, there is a need for the rapid development of new drugs. In silico methods are a modern strategy to explore interactions between new compounds and specific fungal targets, but they depend on precise genetic information. Here, we discuss the main Candida spp. target genes, including information about null mutants, virulence, cytolocalization, co-regulatory genes, and compounds that are related to protein expression. These data will provide a basis for the future in silico development of antifungal drugs.
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25
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Mukaremera L, Lee KK, Mora-Montes HM, Gow NAR. Candida albicans Yeast, Pseudohyphal, and Hyphal Morphogenesis Differentially Affects Immune Recognition. Front Immunol 2017. [PMID: 28638380 PMCID: PMC5461353 DOI: 10.3389/fimmu.2017.00629] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Candida albicans is a human opportunist pathogen that can grow as yeast, pseudohyphae, or true hyphae in vitro and in vivo, depending on environmental conditions. Reversible cellular morphogenesis is an important virulence factor that facilitates invasion of host tissues, escape from phagocytes, and dissemination in the blood stream. The innate immune system is the first line of defense against C. albicans infections and is influenced by recognition of wall components that vary in composition in different morphological forms. However, the relationship between cellular morphogenesis and immune recognition of this fungus is not fully understood. We therefore studied various vegetative cell types of C. albicans, singly and in combination, to assess the consequences of cellular morphogenesis on selected immune cytokine outputs from human monocytes. Hyphae stimulated proportionally lower levels of certain cytokines from monocytes per unit of cell surface area than yeast cells, but did not suppress cytokine response when copresented with yeast cells. Pseudohyphal cells induced intermediate cytokine responses. Yeast monomorphic mutants had elevated cytokine responses under conditions that otherwise supported filamentous growth and mutants of yeast and hyphal cells that were defective in cell wall mannosylation or lacking certain hypha-specific cell wall proteins could variably unmask or deplete the surface of immunostimulatory ligands. These observations underline the critical importance of C. albicans morphology and morphology-associated changes in the cell wall composition that affect both immune recognition and pathogenesis.
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Affiliation(s)
- Liliane Mukaremera
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen, United Kingdom.,Department of Microbiology and Immunology, Medical School, University of Minnesota, Minneapolis, MN, United States
| | - Keunsook K Lee
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen, United Kingdom
| | - Hector M Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Mexico
| | - Neil A R Gow
- Aberdeen Fungal Group, Institute of Medical Sciences, Foresterhill, University of Aberdeen, Aberdeen, United Kingdom
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26
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Teixeira M, Moreno L, Stielow B, Muszewska A, Hainaut M, Gonzaga L, Abouelleil A, Patané J, Priest M, Souza R, Young S, Ferreira K, Zeng Q, da Cunha M, Gladki A, Barker B, Vicente V, de Souza E, Almeida S, Henrissat B, Vasconcelos A, Deng S, Voglmayr H, Moussa T, Gorbushina A, Felipe M, Cuomo C, de Hoog GS. Exploring the genomic diversity of black yeasts and relatives ( Chaetothyriales, Ascomycota). Stud Mycol 2017; 86:1-28. [PMID: 28348446 PMCID: PMC5358931 DOI: 10.1016/j.simyco.2017.01.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The order Chaetothyriales (Pezizomycotina, Ascomycetes) harbours obligatorily melanised fungi and includes numerous etiologic agents of chromoblastomycosis, phaeohyphomycosis and other diseases of vertebrate hosts. Diseases range from mild cutaneous to fatal cerebral or disseminated infections and affect humans and cold-blooded animals globally. In addition, Chaetothyriales comprise species with aquatic, rock-inhabiting, ant-associated, and mycoparasitic life-styles, as well as species that tolerate toxic compounds, suggesting a high degree of versatile extremotolerance. To understand their biology and divergent niche occupation, we sequenced and annotated a set of 23 genomes of main the human opportunists within the Chaetothyriales as well as related environmental species. Our analyses included fungi with diverse life-styles, namely opportunistic pathogens and closely related saprobes, to identify genomic adaptations related to pathogenesis. Furthermore, ecological preferences of Chaetothyriales were analysed, in conjuncture with the order-level phylogeny based on conserved ribosomal genes. General characteristics, phylogenomic relationships, transposable elements, sex-related genes, protein family evolution, genes related to protein degradation (MEROPS), carbohydrate-active enzymes (CAZymes), melanin synthesis and secondary metabolism were investigated and compared between species. Genome assemblies varied from 25.81 Mb (Capronia coronata) to 43.03 Mb (Cladophialophora immunda). The bantiana-clade contained the highest number of predicted genes (12 817 on average) as well as larger genomes. We found a low content of mobile elements, with DNA transposons from Tc1/Mariner superfamily being the most abundant across analysed species. Additionally, we identified a reduction of carbohydrate degrading enzymes, specifically many of the Glycosyl Hydrolase (GH) class, while most of the Pectin Lyase (PL) genes were lost in etiological agents of chromoblastomycosis and phaeohyphomycosis. An expansion was found in protein degrading peptidase enzyme families S12 (serine-type D-Ala-D-Ala carboxypeptidases) and M38 (isoaspartyl dipeptidases). Based on genomic information, a wide range of abilities of melanin biosynthesis was revealed; genes related to metabolically distinct DHN, DOPA and pyomelanin pathways were identified. The MAT (MAting Type) locus and other sex-related genes were recognized in all 23 black fungi. Members of the asexual genera Fonsecaea and Cladophialophora appear to be heterothallic with a single copy of either MAT-1-1 or MAT-1-2 in each individual. All Capronia species are homothallic as both MAT1-1 and MAT1-2 genes were found in each single genome. The genomic synteny of the MAT-locus flanking genes (SLA2-APN2-COX13) is not conserved in black fungi as is commonly observed in Eurotiomycetes, indicating a unique genomic context for MAT in those species. The heterokaryon (het) genes expansion associated with the low selective pressure at the MAT-locus suggests that a parasexual cycle may play an important role in generating diversity among those fungi.
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Affiliation(s)
- M.M. Teixeira
- Division of Pathogen Genomics, Translational Genomics Research Institute (TGen), Flagstaff, AZ, USA
- Department of Cell Biology, University of Brasília, Brasilia, Brazil
| | - L.F. Moreno
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
- Department of Basic Pathology, Federal University of Paraná State, Curitiba, PR, Brazi1
- Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - B.J. Stielow
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - A. Muszewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - M. Hainaut
- Université Aix-Marseille (CNRS), Marseille, France
| | - L. Gonzaga
- The National Laboratory for Scientific Computing (LNCC), Petropolis, Brazil
| | | | - J.S.L. Patané
- Department of Biochemistry, University of São Paulo, Brazil
| | - M. Priest
- Broad Institute of MIT and Harvard, Cambridge, USA
| | - R. Souza
- The National Laboratory for Scientific Computing (LNCC), Petropolis, Brazil
| | - S. Young
- Broad Institute of MIT and Harvard, Cambridge, USA
| | - K.S. Ferreira
- Department of Biological Sciences, Federal University of São Paulo, Diadema, SP, Brazil
| | - Q. Zeng
- Broad Institute of MIT and Harvard, Cambridge, USA
| | - M.M.L. da Cunha
- Núcleo Multidisciplinar de Pesquisa em Biologia UFRJ-Xerém-NUMPEX-BIO, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - A. Gladki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - B. Barker
- Division of Pathogen Genomics, Translational Genomics Research Institute (TGen), Flagstaff, AZ, USA
| | - V.A. Vicente
- Department of Basic Pathology, Federal University of Paraná State, Curitiba, PR, Brazi1
| | - E.M. de Souza
- Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba, PR, Brazil
| | - S. Almeida
- Department of Clinical and Toxicological Analysis, University of São Paulo, São Paulo, SP, Brazil
| | - B. Henrissat
- Université Aix-Marseille (CNRS), Marseille, France
| | - A.T.R. Vasconcelos
- The National Laboratory for Scientific Computing (LNCC), Petropolis, Brazil
| | - S. Deng
- Shanghai Institute of Medical Mycology, Changzheng Hospital, Second Military Medical University, Shanghai, China
| | - H. Voglmayr
- Department of Systematic and Evolutionary Botany, University of Vienna, Vienna, Austria
| | - T.A.A. Moussa
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
- Botany and Microbiology Department, Faculty of Science, Cairo University, Giza, Egypt
| | - A. Gorbushina
- Federal Institute for Material Research and Testing (BAM), Berlin, Germany
| | - M.S.S. Felipe
- Department of Cell Biology, University of Brasília, Brasilia, Brazil
| | - C.A. Cuomo
- Broad Institute of MIT and Harvard, Cambridge, USA
| | - G. Sybren de Hoog
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
- Department of Basic Pathology, Federal University of Paraná State, Curitiba, PR, Brazi1
- Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
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27
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Sem X, Le GTT, Tan ASM, Tso G, Yurieva M, Liao WWP, Lum J, Srinivasan KG, Poidinger M, Zolezzi F, Pavelka N. β-glucan Exposure on the Fungal Cell Wall Tightly Correlates with Competitive Fitness of Candida Species in the Mouse Gastrointestinal Tract. Front Cell Infect Microbiol 2016; 6:186. [PMID: 28066722 PMCID: PMC5177745 DOI: 10.3389/fcimb.2016.00186] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 11/30/2016] [Indexed: 02/03/2023] Open
Abstract
Candida albicans is responsible for ~400,000 systemic fungal infections annually, with an associated mortality rate of 46–75%. The human gastrointestinal (GI) tract represents the largest natural reservoir of Candida species and is a major source of systemic fungal infections. However, the factors that control GI colonization by Candida species are not completely understood. We hypothesized that the fungal cell wall would play an important role in determining the competitive fitness of Candida species in the mammalian GI tract. To test this hypothesis, we generated a systematic collection of isogenic C. albicans cell wall mutants and measured their fitness in the mouse GI tract via quantitative competition assays. Whereas a large variation in competitive fitness was found among mutants, no correlation was observed between GI fitness and total levels of individual cell wall components. Similar results were obtained in a set of distantly-related Candida species, suggesting that total amounts of individual cell wall components do not determine the ability of fungi to colonize the GI tract. We then subjected this collection of Candida strains and species to an extensive quantitative phenotypic profiling in search for features that might be responsible for their differences in GI fitness, but found no association with the ability to grow in GI-mimicking and stressful environments or with in vitro and in vivo virulence. The most significant association with GI fitness was found to be the strength of signaling through the Dectin-1 receptor. Using a quantitative assay to measure the amount of exposed β-glucan on the surface of fungal cells, we found this parameter, unlike total β-glucan levels, to be strongly predictive of competitive fitness in the mouse GI tract. These data suggest that fungal cell wall architecture, more so than its crude composition, critically determines the ability of fungi to colonize the mammalian GI tract. In particular, recognition of exposed β-glucan by Dectin-1 receptor appears to severely limit Candida GI fitness and hence represents a promising target to reduce fungal colonization in patients at risks of systemic candidiasis.
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Affiliation(s)
- XiaoHui Sem
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Giang T T Le
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Alrina S M Tan
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Gloria Tso
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Marina Yurieva
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Webber W P Liao
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Josephine Lum
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | | | - Michael Poidinger
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Francesca Zolezzi
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Norman Pavelka
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
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28
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Degani G, Ragni E, Botias P, Ravasio D, Calderon J, Pianezzola E, Rodriguez-Peña JM, Vanoni MA, Arroyo J, Fonzi WA, Popolo L. Genomic and functional analyses unveil the response to hyphal wall stress in Candida albicans cells lacking β(1,3)-glucan remodeling. BMC Genomics 2016; 17:482. [PMID: 27411447 PMCID: PMC4942948 DOI: 10.1186/s12864-016-2853-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/21/2016] [Indexed: 11/17/2022] Open
Abstract
Background The cell wall is essential for the yeast to hypha (Y-H) transition that enables Candida albicans to invade human tissues and evade the immune system. The main constituent, β(1,3)-glucan, is remodeled by glucanosyltransferases of the GH72 family. Phr1p is responsible of glucan remodeling at neutral-alkaline pH and is essential for morphogenesis and virulence. Due to the pH-regulated expression of PHR1, the phr1Δ phenotype is manifested at pH > 6 and its severity increases with the rise in pH. We exploited the pH-conditional nature of a PHR1 null mutant to analyze the impact of glucan remodeling on the hyphal transcriptional program and the role of chitin synthases in the hyphal wall stress (HWS) response. Results In hyphal growth inducing conditions, phr1Δ germ tubes are defective in elongation, accumulate chitin, and constitutively activate the signaling pathways mediated by the MAP kinases Mkc1p, Cek1p and Hog1p. The transcriptional profiles revealed an increase of transcript levels for genes involved in cell wall formation (CHS2 and CHS8, CRH11, PGA23, orf19.750, RBR1, RBT4, ECM331, PGA6, PGA13), protein N-glycosylation and sorting in the ER (CWH8 and CHS7), signaling (CPP1, SSK2), ion transport (FLC2, YVC1), stress response and metabolism and a reduced expression of adhesins. A transient up-regulation of DNA replication genes associated with entry into S-phase occurred whereas cell-cycle regulating genes (PCL1, PCL2, CCN1, GIN4, DUN1, CDC28) were persistently up-regulated. To test the physiological relevance of altered CHS gene expression, phr1Δ chsxΔ (x = 2,3,8) mutant phenotypes were analyzed during the Y-H transition. PHR1 deletion was synthetic lethal with CHS3 loss on solid M199 medium-pH 7.5 and with CHS8 deletion on solid M199-pH 8. On Spider medium, PHR1 was synthetic lethal with CHS3 or CHS8 at pH 8. Conclusions The absence of Phr1p triggers an adaptive response aimed to reinforce the hyphal cell wall and restore homeostasis. Chs3p is essential in preserving phr1Δ cell integrity during the Y-H transition. Our findings also unveiled an unanticipated essential role of Chs8p during filamentation on solid media. These results highlight the flexibility of fungal cells in maintaining cell wall integrity and contribute to assessments of glucan remodeling as a target for therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2853-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Genny Degani
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Enrico Ragni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.,Present address: Unit of Cell therapy and Cryobiology, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico, Milano, Italy
| | - Pedro Botias
- Unidad de Genómica, CAI de Genómica y Proteómica, UCM, Madrid, Spain
| | - Davide Ravasio
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.,Present address: Evolva, Basel, Switzerland
| | - Julia Calderon
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.,Present address: Instituto de Biología Funcional y Genómica, Salamanca, Spain
| | - Elena Pianezzola
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Jose Manuel Rodriguez-Peña
- Departamento de Microbiologia II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Maria Antonietta Vanoni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy
| | - Javier Arroyo
- Departamento de Microbiologia II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - William A Fonzi
- Department of Microbiology and Immunology, Georgetown University, Washington, D.C, USA
| | - Laura Popolo
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.
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29
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Freitas DFS, Santos SS, Almeida-Paes R, de Oliveira MME, do Valle ACF, Gutierrez-Galhardo MC, Zancopé-Oliveira RM, Nosanchuk JD. Increase in virulence of Sporothrix brasiliensis over five years in a patient with chronic disseminated sporotrichosis. Virulence 2016; 6:112-20. [PMID: 25668479 DOI: 10.1080/21505594.2015.1014274] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The metropolitan region of Rio de Janeiro is hyperendemic for cat-associated sporotrichosis. This study aimed to assess the virulence of serial Sporothrix isolates from a 61-year-old male patient with chronic, destructive disseminated sporotrichosis. Five Sporothrix isolates were cultured from skin exudates and bone samples over a 5-year period, and all were molecularly identified as Sporothrix brasiliensis. The final isolate was significantly more virulent in Galleria mellonella larvae compared to earlier isolates. We conclude that S. brasiliensis has the capacity to increase in virulence in vivo. This finding is significant to clinicians caring for individuals with S. brasiliensis disease and it suggests that further studies are needed to identify the mechanisms underlying pathogenicity enhancement during chronic disease.
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Affiliation(s)
- Dayvison F S Freitas
- a Instituto Nacional de Infectologia Evandro Chagas ; Fiocruz ; Rio de Janeiro , Brazil
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30
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Influence of IgG Subclass on Human Antimannan Antibody-Mediated Resistance to Hematogenously Disseminated Candidiasis in Mice. Infect Immun 2015; 84:386-94. [PMID: 26573736 DOI: 10.1128/iai.00890-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/06/2015] [Indexed: 01/23/2023] Open
Abstract
Candida albicans is a yeast-like pathogen and can cause life-threatening systemic candidiasis. Its cell surface is enriched with mannan that is resistant to complement activation. Previously, we developed the recombinant human IgG1 antimannan antibody M1g1. M1g1 was found to promote complement activation and phagocytosis and protect mice from systemic candidiasis. Here, we evaluate the influence of IgG subclass on antimannan antibody-mediated protection. Three IgG subclass variants of M1g1 were constructed: M1g2, M1g3, and M1g4. The IgG subclass identity for each variant was confirmed with DNA sequence and subclass-specific antibodies. These variants contain identical M1 Fabs and exhibited similar binding affinities for C. albicans yeast and purified mannan. Yeast cells and hyphae recovered from the kidney of antibody-treated mice with systemic candidiasis showed uniform binding of each variant, indicating constitutive expression of the M1 epitope and antibody opsonization in the kidney. All variants promoted deposition of both murine and human C3 onto the yeast cell surface, with M1g4 showing delayed activation, as determined by flow cytometry and immunofluorescence microscopy. M1g4-mediated complement activation was found to be associated with its M1 Fab that activates the alternative pathway in an Fc-independent manner. Treatment with each subclass variant extended the survival of mice with systemic candidiasis (P < 0.001). However, treatment with M1g1, M1g3, or M1g4, but not with M1g2, also reduced the kidney fungal burden (P < 0.001). Thus, the role of human antimannan antibody in host resistance to systemic candidiasis is influenced by its IgG subclass.
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31
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Preechasuth K, Anderson JC, Peck SC, Brown AJP, Gow NAR, Lenardon MD. Cell wall protection by the Candida albicans class I chitin synthases. Fungal Genet Biol 2015; 82:264-76. [PMID: 26257018 PMCID: PMC4557417 DOI: 10.1016/j.fgb.2015.08.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 01/20/2023]
Abstract
Candida albicans has four chitin synthases from three different enzyme classes which deposit chitin in the cell wall, including at the polarized tips of growing buds and hyphae, and sites of septation. The two class I enzymes, Chs2 and Chs8, are responsible for most of the measurable chitin synthase activity in vitro, but their precise biological functions in vivo remain obscure. In this work, detailed phenotypic analyses of a chs2Δchs8Δ mutant have shown that C. albicans class I chitin synthases promote cell integrity during early polarized growth in yeast and hyphal cells. This was supported by live cell imaging of YFP-tagged versions of the class I chitin synthases which revealed that Chs2-YFP was localized at sites of polarized growth. Furthermore, a unique and dynamic pattern of localization of the class I enzymes at septa of yeast and hyphae was revealed. Phosphorylation of Chs2 on the serine at position 222 was shown to regulate the amount of Chs2 that is localized to sites of polarized growth and septation. Independently from this post-translational modification, specific cell wall stresses were also shown to regulate the amount of Chs2 that localizes to specific sites in cells, and this was linked to the ability of the class I enzymes to reinforce cell wall integrity during early polarized growth in the presence of these stresses.
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Affiliation(s)
- Kanya Preechasuth
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
| | - Jeffrey C Anderson
- Division of Biochemistry, 271H Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA.
| | - Scott C Peck
- Division of Biochemistry, 271H Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA.
| | - Alistair J P Brown
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
| | - Neil A R Gow
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
| | - Megan D Lenardon
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
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32
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Fajardo-Somera RA, Jöhnk B, Bayram Ö, Valerius O, Braus GH, Riquelme M. Dissecting the function of the different chitin synthases in vegetative growth and sexual development in Neurospora crassa. Fungal Genet Biol 2015; 75:30-45. [DOI: 10.1016/j.fgb.2015.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/17/2014] [Accepted: 01/07/2015] [Indexed: 01/22/2023]
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33
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Walker LA, Lenardon MD, Preechasuth K, Munro CA, Gow NAR. Cell wall stress induces alternative fungal cytokinesis and septation strategies. J Cell Sci 2013; 126:2668-77. [PMID: 23606739 DOI: 10.1242/jcs.118885] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In fungi, as with all walled organisms, cytokinesis followed by septation marks the end of the cell cycle and is essential for cell division and viability. For yeasts, the septal cross-wall comprises a ring and primary septal plate composed of chitin, and a secondary septum thickened with β(1,3)-glucan. In the human pathogen Candida albicans, chitin synthase enzyme Chs1 builds the primary septum that is surrounded by a chitin ring made by Chs3. Here we show that the lethal phenotype induced by repression of CHS1 was abrogated by stress-induced synthesis of alternative and novel septal types synthesized by other chitin synthase enzymes that have never before been implicated in septation. Chs2 and Chs8 formed a functional salvage septum, even in the absence of both Chs1 and Chs3. A second type of salvage septum formed by Chs2 in combination with Chs3 or Chs8 was proximally offset in the mother-bud neck. Chs3 alone or in combination with Chs8 formed a greatly thickened third type of salvage septum. Therefore, cell wall stress induced alternative forms of septation that rescued cell division in the absence of Chs1, demonstrating that fungi have previously unsuspected redundant strategies to enable septation and cell division to be maintained, even under potentially lethal environmental conditions.
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Affiliation(s)
- Louise A Walker
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
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Zeidler U, Bougnoux ME, Lupan A, Helynck O, Doyen A, Garcia Z, Sertour N, Clavaud C, Munier-Lehmann H, Saveanu C, d'Enfert C. Synergy of the antibiotic colistin with echinocandin antifungals in Candida species. J Antimicrob Chemother 2013; 68:1285-96. [PMID: 23378416 DOI: 10.1093/jac/dks538] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Candida albicans is the most prevalent fungal pathogen of humans, causing a wide range of infections from harmless superficial to severe systemic infections. Improvement of the antifungal arsenal is needed since existing antifungals can be associated with limited efficacy, toxicity and antifungal resistance. Here we aimed to identify compounds that act synergistically with echinocandin antifungals and that could contribute to a faster reduction of the fungal burden. METHODS A total of 38 758 compounds were tested for their ability to act synergistically with aminocandin, a β-1,3-glucan synthase inhibitor of the echinocandin family of antifungals. The synergy between echinocandins and an identified hit was studied with chemogenomic screens and testing of individual Saccharomyces cerevisiae and C. albicans mutant strains. RESULTS We found that colistin, an antibiotic that targets membranes in Gram-negative bacteria, is synergistic with drugs of the echinocandin family against all Candida species tested. The combination of colistin and aminocandin led to faster and increased permeabilization of C. albicans cells than either colistin or aminocandin alone. Echinocandin susceptibility was a prerequisite to be able to observe the synergy. A large-scale screen for genes involved in natural resistance of yeast cells to low doses of the drugs, alone or in combination, identified efficient sphingolipid and chitin biosynthesis as necessary to protect S. cerevisiae and C. albicans cells against the antifungal combination. CONCLUSIONS These results suggest that echinocandin-mediated weakening of the cell wall facilitates colistin targeting of fungal membranes, which in turn reinforces the antifungal activity of echinocandins.
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Affiliation(s)
- Ute Zeidler
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Département Génomes et Génétique, F-75015 Paris, France
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Costa-de-Oliveira S, Silva AP, Miranda IM, Salvador A, Azevedo MM, Munro CA, Rodrigues AG, Pina-Vaz C. Determination of chitin content in fungal cell wall: an alternative flow cytometric method. Cytometry A 2013; 83:324-8. [PMID: 23359335 DOI: 10.1002/cyto.a.22250] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 11/05/2022]
Abstract
The conventional methods used to evaluate chitin content in fungi, such as biochemical assessment of glucosamine release after acid hydrolysis or epifluorescence microscopy, are low throughput, laborious, time-consuming, and cannot evaluate a large number of cells. We developed a flow cytometric assay, efficient, and fast, based on Calcofluor White staining to measure chitin content in yeast cells. A staining index was defined, its value was directly related to chitin amount and taking into consideration the different levels of autofluorecence. Twenty-two Candida spp. and four Cryptococcus neoformans clinical isolates with distinct susceptibility profiles to caspofungin were evaluated. Candida albicans clinical isolate SC5314, and isogenic strains with deletions in chitin synthase 3 (chs3Δ/chs3Δ) and genes encoding predicted GlycosylPhosphatidylInositol (GPI)-anchored proteins (pga31Δ/Δ and pga62Δ/Δ), were used as controls. As expected, the wild-type strain displayed a significant higher chitin content (P < 0.001) than chs3Δ/chs3Δ and pga31Δ/Δ especially in the presence of caspofungin. Ca. parapsilosis, Ca. tropicalis, and Ca. albicans showed higher cell wall chitin content. Although no relationship between chitin content and antifungal drug susceptibility phenotype was found, an association was established between the paradoxical growth effect in the presence of high caspofungin concentrations and the chitin content. This novel flow cytometry protocol revealed to be a simple and reliable assay to estimate cell wall chitin content of fungi.
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Affiliation(s)
- Sofia Costa-de-Oliveira
- Department of Microbiology, Faculty of Medicine, University of Porto, Alameda Prof. Hernani Monteiro, Porto 4200-319, Portugal.
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Munro CA. Chitin and glucan, the yin and yang of the fungal cell wall, implications for antifungal drug discovery and therapy. ADVANCES IN APPLIED MICROBIOLOGY 2013; 83:145-72. [PMID: 23651596 DOI: 10.1016/b978-0-12-407678-5.00004-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The structural carbohydrate polymers glucan and chitin compliment and reinforce each other in a dynamic process to maintain the integrity and physical strength of the fungal cell wall. The assembly of chitin and glucan in the cell wall of the budding yeast Saccharomyces cerevisiae and the polymorphic human pathogen Candida albicans are essential processes that involve a range of fungal-specific enzymes and regulatory networks. The fungal cell wall is, therefore, an attractive target for novel therapies as host cells lack many cell wall-related proteins. The most recent class of antifungal drug approved for clinical use, the echinocandins, targets the synthesis of cell wall β(1-3)glucan. The echinocandins are effective at treating invasive and bloodstream Candida infections and are now widely used in the clinic. However, there have been sporadic reports of breakthrough infections in patients undergoing echinocandin therapy. The acquisition of point mutations in the FKS genes that encode the catalytic β(1-3)glucan synthase subunits, the target of the echinocandins, has emerged as a dominant resistance mechanism. Cells with elevated chitin levels are also less susceptible to echinocandins and in addition, treatment with sub-MIC echinocandin activates cell wall salvage pathways that increase chitin synthesis to compensate for reduced glucan production. The development of drugs targeting the cell wall has already proven to be beneficial in providing an alternative class of drug for use in the clinic. Other cell wall targets such as chitin synthesis still hold great potential for drug development but careful consideration should be given to the capacity of fungi to manipulate their walls in a dynamic response to cell wall perturbations.
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Affiliation(s)
- Carol A Munro
- School of Medical Sciences, University of Aberdeen, Aberdeen, UK, E-mail:
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37
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Tierney L, Linde J, Müller S, Brunke S, Molina JC, Hube B, Schöck U, Guthke R, Kuchler K. An Interspecies Regulatory Network Inferred from Simultaneous RNA-seq of Candida albicans Invading Innate Immune Cells. Front Microbiol 2012; 3:85. [PMID: 22416242 PMCID: PMC3299011 DOI: 10.3389/fmicb.2012.00085] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/20/2012] [Indexed: 12/31/2022] Open
Abstract
The ability to adapt to diverse micro-environmental challenges encountered within a host is of pivotal importance to the opportunistic fungal pathogen Candida albicans. We have quantified C. albicans and M. musculus gene expression dynamics during phagocytosis by dendritic cells in a genome-wide, time-resolved analysis using simultaneous RNA-seq. A robust network inference map was generated from this dataset using NetGenerator, predicting novel interactions between the host and the pathogen. We experimentally verified predicted interdependent sub-networks comprising Hap3 in C. albicans, and Ptx3 and Mta2 in M. musculus. Remarkably, binding of recombinant Ptx3 to the C. albicans cell wall was found to regulate the expression of fungal Hap3 target genes as predicted by the network inference model. Pre-incubation of C. albicans with recombinant Ptx3 significantly altered the expression of Mta2 target cytokines such as IL-2 and IL-4 in a Hap3-dependent manner, further suggesting a role for Mta2 in host-pathogen interplay as predicted in the network inference model. We propose an integrated model for the functionality of these sub-networks during fungal invasion of immune cells, according to which binding of Ptx3 to the C. albicans cell wall induces remodeling via fungal Hap3 target genes, thereby altering the immune response to the pathogen. We show the applicability of network inference to predict interactions between host-pathogen pairs, demonstrating the usefulness of this systems biology approach to decipher mechanisms of microbial pathogenesis.
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Affiliation(s)
- Lanay Tierney
- Christian Doppler Laboratory for Infection Biology, Max F. Perutz Laboratories, Medical University of Vienna Vienna, Austria
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38
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Rogg LE, Fortwendel JR, Juvvadi PR, Steinbach WJ. Regulation of expression, activity and localization of fungal chitin synthases. Med Mycol 2012; 50:2-17. [PMID: 21526913 PMCID: PMC3660733 DOI: 10.3109/13693786.2011.577104] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The fungal cell wall represents an attractive target for pharmacologic inhibition, as many of the components are fungal-specific. Though targeted inhibition of β-glucan synthesis is effective treatment for certain fungal infections, the ability of the cell wall to dynamically compensate via the cell wall integrity pathway may limit overall efficacy. To date, chitin synthesis inhibitors have not been successfully deployed in the clinical setting. Fungal chitin synthesis is a complex and highly regulated process. Regulation of chitin synthesis occurs on multiple levels, thus targeting of these regulatory pathways may represent an exciting alternative approach. A variety of signaling pathways have been implicated in chitin synthase regulation, at both transcriptional and post-transcriptional levels. Recent research suggests that localization of chitin synthases likely represents a major regulatory mechanism. However, much of the regulatory machinery is not necessarily shared among different chitin synthases. Thus, an in-depth understanding of the precise roles of each protein in cell wall maintenance and repair will be essential to identifying the most likely therapeutic targets.
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Affiliation(s)
- Luise E. Rogg
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - Jarrod R. Fortwendel
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
| | - Praveen R. Juvvadi
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - William J. Steinbach
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
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39
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Guimarães AJ, de Cerqueira MD, Nosanchuk JD. Surface architecture of histoplasma capsulatum. Front Microbiol 2011; 2:225. [PMID: 22121356 PMCID: PMC3220077 DOI: 10.3389/fmicb.2011.00225] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 10/25/2011] [Indexed: 12/22/2022] Open
Abstract
The dimorphic fungal pathogen Histoplasma capsulatum is the most frequent cause of clinically significant fungal pneumonia in humans. H. capsulatum virulence is achieved, in part, through diverse and dynamic alterations to the fungal cell surface. Surface components associated with H. capsulatum pathogenicity include carbohydrates, lipids, proteins, and melanins. Here, we describe the various structures comprising the cell surface of H. capsulatum that have been associated with virulence and discuss their involvement in the pathobiology of disease.
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Affiliation(s)
- Allan J Guimarães
- Department of Microbiology and Imunology, Albert Einstein College of Medicine of Yeshiva University Bronx, NY, USA
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40
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Elevated cell wall chitin in Candida albicans confers echinocandin resistance in vivo. Antimicrob Agents Chemother 2011; 56:208-17. [PMID: 21986821 DOI: 10.1128/aac.00683-11] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida albicans cells with increased cell wall chitin have reduced echinocandin susceptibility in vitro. The aim of this study was to investigate whether C. albicans cells with elevated chitin levels have reduced echinocandin susceptibility in vivo. BALB/c mice were infected with C. albicans cells with normal chitin levels and compared to mice infected with high-chitin cells. Caspofungin therapy was initiated at 24 h postinfection. Mice infected with chitin-normal cells were successfully treated with caspofungin, as indicated by reduced kidney fungal burdens, reduced weight loss, and decreased C. albicans density in kidney lesions. In contrast, mice infected with high-chitin C. albicans cells were less susceptible to caspofungin, as they had higher kidney fungal burdens and greater weight loss during early infection. Cells recovered from mouse kidneys at 24 h postinfection with high-chitin cells had 1.6-fold higher chitin levels than cells from mice infected with chitin-normal cells and maintained a significantly reduced susceptibility to caspofungin when tested in vitro. At 48 h postinfection, caspofungin treatment induced a further increase in chitin content of C. albicans cells harvested from kidneys compared to saline treatment. Some of the recovered clones had acquired, at a low frequency, a point mutation in FKS1 resulting in a S645Y amino acid substitution, a mutation known to confer echinocandin resistance. This occurred even in cells that had not been exposed to caspofungin. Our results suggest that the efficacy of caspofungin against C. albicans was reduced in vivo due to either elevation of chitin levels in the cell wall or acquisition of FKS1 point mutations.
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41
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Rogg LE, Fortwendel JR, Juvvadi PR, Lilley A, Steinbach WJ. The chitin synthase genes chsA and chsC are not required for cell wall stress responses in the human pathogen Aspergillus fumigatus. Biochem Biophys Res Commun 2011; 411:549-54. [PMID: 21763289 DOI: 10.1016/j.bbrc.2011.06.180] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 06/30/2011] [Indexed: 11/30/2022]
Abstract
Invasive aspergillosis is a leading cause of mortality in immunocompromised patients. The fungal cell wall is an attractive antifungal target, but it is dynamic and responsive to external stressors. The existence of multiple chitin synthases within Aspergilli is thought to reflect specialized functions in cell wall damage responses that facilitate continued growth and viability. We previously reported increased transcription of Aspergillus fumigatus chitin synthases chsA and chsC following echinocandin treatment, suggesting important roles for these chitin synthases in cell wall compensation. As only partial disruptions have been made of these genes, we generated deletion mutants of chsA and chsC singly (ΔchsA and ΔchsC) and doubly (ΔchsA ΔchsC). The ΔchsA ΔchsC strain displayed reduced total chitin synthase activity. Interestingly, deletion of these chitin synthase genes did not affect levels of chitin or β-1,3-glucan.The ΔchsA, ΔchsC and ΔchsA ΔchsC strains produced wild-type echinocandin-mediated chitin increases, consistent with unaltered cell wall compensation. Furthermore, transcript levels of the remaining chitin synthase genes were unchanged in the mutant strains. Taken together, these results indicate that chsA and chsC do not play a direct role in the cell wall stress response. Our findings support the existence of complex post-transcriptional regulatory mechanisms controlling chitin biosynthetic machinery in response to cell wall damage.
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Affiliation(s)
- Luise E Rogg
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA
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42
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Ueno K, Namiki Y, Mitani H, Yamaguchi M, Chibana H. Differential cell wall remodeling of two chitin synthase deletants Δchs3A and Δchs3B in the pathogenic yeast Candida glabrata. FEMS Yeast Res 2011; 11:398-407. [PMID: 21453325 DOI: 10.1111/j.1567-1364.2011.00728.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
It is known that cell wall remodeling and the salvaging pathway act to compensate for an impaired or a damaged cell wall. Lately, it has been indicated that this mechanism is partly required for resistance to the glucan synthesis inhibitor echinocandin. While cell wall remodeling has been described in mutants of glucan or mannan synthesis, it has not yet been reported in a chitin synthesis mutant. Here, we describe a novel cell wall remodeling and salvaging pathway in chitin synthesis mutants, Δchs3A and Δchs3B, of the pathogenic yeast Candida glabrata. Electron microscopic analysis revealed a thickened mannoprotein layer in Δchs3A cells and a thickened chitin-glucan layer of Δchs3B cells, and it indicated the hypothesis that mannan synthase and chitin-glucan synthase indemnify Δchs3A and Δchs3B cells, respectively. The double-mutant CHS3A and MNN10, encoding α-1,6-mannosyltransferase, showed synergistic stress sensitization, and the Δchs3B strain showed supersensitivity to echinocandins. Hence, these findings support the above hypothesis of remodeling. Furthermore, unlike Δchs3A cells, Δchs3B cells showed supersensitivity to calcineurin inhibitor FK506 and Tor1p kinase inhibitor rapamycin, indicating that the Δchs3B strain uses the calcineurin pathway and a Tor1p kinase for cell wall remodeling.
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Affiliation(s)
- Keigo Ueno
- Medical Mycology Research Center, Chiba University, Chuo-ku, Japan
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43
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Recognition and blocking of innate immunity cells by Candida albicans chitin. Infect Immun 2011; 79:1961-70. [PMID: 21357722 DOI: 10.1128/iai.01282-10] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Chitin is a skeletal cell wall polysaccharide of the inner cell wall of fungal pathogens. As yet, little about its role during fungus-host immune cell interactions is known. We show here that ultrapurified chitin from Candida albicans cell walls did not stimulate cytokine production directly but blocked the recognition of C. albicans by human peripheral blood mononuclear cells (PBMCs) and murine macrophages, leading to significant reductions in cytokine production. Chitin did not affect the induction of cytokines stimulated by bacterial cells or lipopolysaccharide (LPS), indicating that blocking was not due to steric masking of specific receptors. Toll-like receptor 2 (TLR2), TLR4, and Mincle (the macrophage-inducible C-type lectin) were not required for interactions with chitin. Dectin-1 was required for immune blocking but did not bind chitin directly. Cytokine stimulation was significantly reduced upon stimulation of PBMCs with heat-killed chitin-deficient C. albicans cells but not with live cells. Therefore, chitin is normally not exposed to cells of the innate immune system but is capable of influencing immune recognition by blocking dectin-1-mediated engagement with fungal cell walls.
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44
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Chotirmall SH, Greene CM, McElvaney NG. Candidaspecies in cystic fibrosis: A road less travelled. Med Mycol 2010; 48 Suppl 1:S114-24. [DOI: 10.3109/13693786.2010.503320] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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45
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Keppler-Ross S, Douglas L, Konopka JB, Dean N. Recognition of yeast by murine macrophages requires mannan but not glucan. EUKARYOTIC CELL 2010; 9:1776-87. [PMID: 20833894 PMCID: PMC2976302 DOI: 10.1128/ec.00156-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 09/02/2010] [Indexed: 11/20/2022]
Abstract
The first barrier against infection by Candida albicans involves fungal recognition and destruction by phagocytic cells of the innate immune system. It is well established that interactions between different phagocyte receptors and components of the fungal cell wall trigger phagocytosis and subsequent immune responses, but the fungal ligands mediating the initial stage of recognition have not been identified. Here, we describe a novel assay for fungal recognition and uptake by macrophages which monitors this early recognition step independently of other downstream events of phagocytosis. To analyze infection in live macrophages, we validated the neutrality of a codon-optimized red fluorescent protein (yEmRFP) biomarker in C. albicans; growth, hyphal formation, and virulence in infected mice and macrophages were unaffected by yEmRFP production. This permitted a new approach for studying phagocytosis by carrying out competition assays between red and green fluorescent yeast cells to measure the efficiency of yeast uptake by murine macrophages as a function of dimorphism or cell wall defects. These competition experiments demonstrate that, given a choice, macrophages display strong preferences for phagocytosis based on genus, species, and morphology. Candida glabrata and Saccharomyces cerevisiae are taken up by J774 macrophage cells more rapidly than C. albicans, and C. albicans yeast cells are favored over hyphal cells. Significantly, these preferences are mannan dependent. Mutations that affect mannan, but not those that affect glucan or chitin, reduce the uptake of yeast challenged with wild-type competitors by both J774 and primary murine macrophages. These results suggest that mannose side chains or mannosylated proteins are the ligands recognized by murine macrophages prior to fungal uptake.
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Affiliation(s)
| | - Lois Douglas
- Department of Microbiology, Stony Brook University, Stony Brook, New York 11794-5215
| | - James B. Konopka
- Department of Microbiology, Stony Brook University, Stony Brook, New York 11794-5215
| | - Neta Dean
- Department of Biochemistry and Cell Biology
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46
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Walker CA, Gómez BL, Mora-Montes HM, Mackenzie KS, Munro CA, Brown AJP, Gow NAR, Kibbler CC, Odds FC. Melanin externalization in Candida albicans depends on cell wall chitin structures. EUKARYOTIC CELL 2010; 9:1329-42. [PMID: 20543065 PMCID: PMC2937336 DOI: 10.1128/ec.00051-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 06/01/2010] [Indexed: 01/03/2023]
Abstract
The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Delta and chs2Delta chs3Delta mutants but were fully externalized in chs8Delta and chs2Delta chs8Delta mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization.
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Affiliation(s)
- Claire A. Walker
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Beatriz L. Gómez
- Department of Medical Microbiology, Royal Free Hampstead NHS Trust, Pond Street, London NW3 2QG, United Kingdom
| | - Héctor M. Mora-Montes
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Kevin S. Mackenzie
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Carol A. Munro
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Alistair J. P. Brown
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Neil A. R. Gow
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
| | - Christopher C. Kibbler
- Department of Medical Microbiology, Royal Free Hampstead NHS Trust, Pond Street, London NW3 2QG, United Kingdom
| | - Frank C. Odds
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Aberdeen AB25 2ZD, United Kingdom
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47
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Lenardon MD, Milne SA, Mora-Montes HM, Kaffarnik FAR, Peck SC, Brown AJP, Munro CA, Gow NAR. Phosphorylation regulates polarisation of chitin synthesis in Candida albicans. J Cell Sci 2010; 123:2199-206. [PMID: 20530569 DOI: 10.1242/jcs.060210] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability to undergo polarised cell growth is fundamental to the development of almost all walled organisms. Fungi are characterised by yeasts and moulds, and both cellular forms have been studied extensively as tractable models of cell polarity. Chitin is a hallmark component of fungal cell walls. Chitin synthesis is essential for growth, viability and rescue from many conditions that impair cell-wall integrity. In the polymorphic human pathogen Candida albicans, chitin synthase 3 (Chs3) synthesises the majority of chitin in the cell wall and is localised at the tips of growing buds and hyphae, and at the septum. An analysis of the C. albicans phospho-proteome revealed that Chs3 can be phosphorylated at Ser139. Mutation of this site showed that both phosphorylation and dephosphorylation are required for the correct localisation and function of Chs3. The kinase Pkc1 was not required to target Chs3 to sites of polarised growth. This is the first report demonstrating an essential role for chitin synthase phosphorylation in the polarised biosynthesis of fungal cell walls and suggests a new mechanism for the regulation of this class of glycosyl-transferase enzyme.
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Affiliation(s)
- Megan D Lenardon
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, Scotland, UK
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48
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Lenardon MD, Munro CA, Gow NAR. Chitin synthesis and fungal pathogenesis. Curr Opin Microbiol 2010; 13:416-23. [PMID: 20561815 PMCID: PMC2923753 DOI: 10.1016/j.mib.2010.05.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 05/04/2010] [Accepted: 05/06/2010] [Indexed: 11/25/2022]
Abstract
Chitin is an essential part of the carbohydrate skeleton of the fungal cell wall and is a molecule that is not represented in humans and other vertebrates. Complex regulatory mechanisms enable chitin to be positioned at specific sites throughout the cell cycle to maintain the overall strength of the wall and enable rapid, life-saving modifications to be made under cell wall stress conditions. Chitin has also recently emerged as a significant player in the activation and attenuation of immune responses to fungi and other chitin-containing parasites. This review summarises latest advances in the analysis of chitin synthesis regulation in the context of fungal pathogenesis.
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Affiliation(s)
- Megan D Lenardon
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK
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49
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Mora-Montes HM, Ponce-Noyola P, Villagómez-Castro JC, Gow NA, Flores-Carreón A, López-Romero E. Protein glycosylation in Candida. Future Microbiol 2010; 4:1167-83. [PMID: 19895219 DOI: 10.2217/fmb.09.88] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Candidiasis is a significant cause of invasive human mycosis with associated mortality rates that are equivalent to, or worse than, those cited for most cases of bacterial septicemia. As a result, considerable efforts are being made to understand how the fungus invades host cells and to identify new targets for fungal chemotherapy. This has led to an increasing interest in Candida glycobiology, with an emphasis on the identification of enzymes essential for glycoprotein and adhesion metabolism, and the role of N- and O-linked glycans in host recognition and virulence. Here, we refer to studies dealing with the identification and characterization of enzymes such as dolichol phosphate mannose synthase, dolichol phosphate glucose synthase and processing glycosidases and synthesis, structure and recognition of mannans and discuss recent findings in the context of Candida albicans pathogenesis.
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Lenardon MD, Lesiak I, Munro CA, Gow NAR. Dissection of the Candida albicans class I chitin synthase promoters. Mol Genet Genomics 2009; 281:459-71. [PMID: 19153767 PMCID: PMC3468743 DOI: 10.1007/s00438-009-0423-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 01/05/2009] [Indexed: 11/24/2022]
Abstract
Maintenance of the integrity of the cell wall in fungi is essential. One mechanism that cells use to maintain cell wall integrity in response to cell wall damage is to up-regulate chitin synthesis. In Candida albicans, the PKC cell wall integrity, Ca(2+)/calcineurin and high osmolarity glycerol (HOG) signalling pathways co-ordinately regulate chitin synthesis in response to cell wall stress. The transcription factors downstream of these pathways and their DNA binding sites within the promoters of target genes are well characterised in Saccharomyces cerevisiae, but not in C. albicans. The promoters of the C. albicans class I CHS genes (CaCHS2 and CaCHS8) were functionally dissected with the aim of identifying and characterising the transcription factors and promoter elements that mediate the transcriptional up-regulation of CaCHS2 and CaCHS8 in response to cell wall stress. This analysis provided evidence that the PKC cell wall integrity pathway may operate through RLM1-elements in the CaCHS2 and CaCHS8 promoters, but that promoter sequences that respond to the Ca(2+)/calcineurin and HOG signalling pathways in S. cerevisiae did not directly regulate chitin synthase 2 and 8 gene transcription in C. albicans.
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Affiliation(s)
- Megan D. Lenardon
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD Scotland, UK
| | - Iwona Lesiak
- Present Address: Department for Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Fritz-Preglstr. 3, 6020 Innsbruck, Austria
| | - Carol A. Munro
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD Scotland, UK
| | - Neil A. R. Gow
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD Scotland, UK
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