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Gavandi TC, Basrani ST, Chougule SA, Patil SB, Nille OS, Kolekar GB, Yankanchi SR, Karuppayil SM, Jadhav AK. Vidarabine as a novel antifungal agent against Candida albicans: insights on mechanism of action. Int Microbiol 2024:10.1007/s10123-024-00565-z. [PMID: 39126447 DOI: 10.1007/s10123-024-00565-z] [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: 09/07/2023] [Revised: 05/11/2024] [Accepted: 07/31/2024] [Indexed: 08/12/2024]
Abstract
Around 1.5 million mortality cases due to fungal infection are reported annually, posing a massive threat to global health. However, the effectiveness of current antifungal therapies in the treatment of invasive fungal infections is limited. Repurposing existing antifungal drugs is an advisable alternative approach for enhancing their effectiveness. This study evaluated the antifungal efficacy of the antiviral drug vidarabine against Candida albicans ATCC 90028. Antifungal susceptibility testing was performed by microbroth dilution assay and further processed to find the minimum fungicidal concentration. Investigation on probable mode of vidarabine action against C. albicans was assessed by using the ergosterol reduction assay, reactive oxygen species (ROS) accumulation, nuclear condensation, and apoptosis assay. Results revealed that C. albicans was susceptible to vidarabine action and exhibited minimum inhibitory concentration at 150 µg/ml. At a concentration of 300 µg/ml, vidarabine had fungicidal activity against C. albicans. 300 µg/ml vidarabine-treated C. albicans cells demonstrated 91% reduced ergosterol content. Annexin/FITC/PI assay showed that vidarabine (150 µg/ml) had increased late apoptotic cells up to 31%. As per the fractional inhibitory concentration index, vidarabine had synergistic activity with fluconazole and caspofungin against this fungus. The mechanism underlying fungicidal action of vidarabine was evaluated at the intracellular level, and probably because of increased nuclear condensation, enhanced ROS generation, and cell cycle arrest. In conclusion, this data is the first to report that vidarabine has potential to be used as a repurposed antifungal agent alone or in combination with standard antifungal drugs, and could be a quick and safe addition to existing therapies for treating fungal infections.
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Affiliation(s)
- Tanjila C Gavandi
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India
| | - Sargun T Basrani
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India
| | - Sayali A Chougule
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India
| | - Shivani B Patil
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India
| | - Omkar S Nille
- Department of Chemistry, Shivaji University, Kolhapur, 416-004, Maharashtra, India
| | - Govind B Kolekar
- Department of Chemistry, Shivaji University, Kolhapur, 416-004, Maharashtra, India
| | | | - S Mohan Karuppayil
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India.
| | - Ashwini K Jadhav
- Department of Stem Cell and Regenerative Medicine, Medical Biotechnology, Centre for Interdisciplinary Research, D. Y. Patil Education Society (Deemed to be University), Kolhapur, 416-003, Maharashtra, India.
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Xiong EH, Zhang X, Yan H, Ward HN, Lin ZY, Wong CJ, Fu C, Gingras AC, Noble SM, Robbins N, Myers CL, Cowen LE. Functional genomic analysis of genes important for Candida albicans fitness in diverse environmental conditions. Cell Rep 2024; 43:114601. [PMID: 39126650 DOI: 10.1016/j.celrep.2024.114601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 06/20/2024] [Accepted: 07/23/2024] [Indexed: 08/12/2024] Open
Abstract
Fungal pathogens such as Candida albicans pose a significant threat to human health with limited treatment options available. One strategy to expand the therapeutic target space is to identify genes important for pathogen growth in host-relevant environments. Here, we leverage a pooled functional genomic screening strategy to identify genes important for fitness of C. albicans in diverse conditions. We identify an essential gene with no known Saccharomyces cerevisiae homolog, C1_09670C, and demonstrate that it encodes subunit 3 of replication factor A (Rfa3). Furthermore, we apply computational analyses to identify functionally coherent gene clusters and predict gene function. Through this approach, we predict the cell-cycle-associated function of C3_06880W, a previously uncharacterized gene required for fitness specifically at elevated temperatures, and follow-up assays confirm that C3_06880W encodes Iml3, a component of the C. albicans kinetochore with roles in virulence in vivo. Overall, this work reveals insights into the vulnerabilities of C. albicans.
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Affiliation(s)
- Emily H Xiong
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Xiang Zhang
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Huijuan Yan
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Henry N Ward
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Bioinformatics and Computational Biology Graduate Program, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhen-Yuan Lin
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada
| | - Cassandra J Wong
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada
| | - Ci Fu
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Anne-Claude Gingras
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health, Toronto, ON M5G 1X5, Canada
| | - Suzanne M Noble
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Bioinformatics and Computational Biology Graduate Program, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
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3
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Zhang X, Liew KJ, Cao L, Wang J, Chang Z, Tan MCY, Chong KL, Chong CS. Transcriptome analysis of Candida albicans planktonic cells in response to plasma medicine. J Med Microbiol 2024; 73. [PMID: 38967406 DOI: 10.1099/jmm.0.001841] [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] [Indexed: 07/06/2024] Open
Abstract
Introduction. Cold plasma is frequently utilized for the purpose of eliminating microbial contaminants. Under optimal conditions, it can function as plasma medicine for treating various diseases, including infections caused by Candida albicans, an opportunistic pathogen that can overgrow in individuals with weakened immune system.Gap Statement. To date, there has been less molecular study on cold plasma-treated C. albicans.Research Aim. The study aims to fill the gap in understanding the molecular response of C. albicans to cold plasma treatment.Methodology. This project involved testing a cold plasma generator to determine its antimicrobial effectiveness on C. albicans' planktonic cells. Additionally, the cells' transcriptomics responses were investigated using RNA sequencing at various treatment durations (1, 3 and 5 min).Results. The results show that our cold plasma effectively eliminates C. albicans. Cold plasma treatment resulted in substantial downregulation of important pathways, such as 'nucleotide metabolism', 'DNA replication and repair', 'cell growth', 'carbohydrate metabolism' and 'amino acid metabolism'. This was an indication of cell cycle arrest of C. albicans to preserve energy consumption under unfavourable conditions. Nevertheless, C. albicans adapted its GSH antioxidant system to cope with the oxidative stress induced by reactive oxygen species, reactive nitrogen species and other free radicals. The treatment likely led to a decrease in cell pathogenicity as many virulence factors were downregulated.Conclusion. The study demonstrated the major affected pathways in cold plasma-treated C. albicans, providing valuable insights into the molecular response of C. albicans to cold plasma treatment. The findings contribute to the understanding of the antimicrobial efficiency of cold plasma and its potential applications in the field of microbiology.
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Affiliation(s)
- Xinhua Zhang
- School of Photoelectric Engineering, Changzhou Institute of Technology, Changzhou 213028, PR China
- Suzhou Amazing Grace Medical Equipment Co., Ltd, Suzhou 215101, PR China
- Jiangsu Huayu Printing & Coating Equipment Co. Ltd, Nantong 226300, PR China
| | - Kok Jun Liew
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Li Cao
- Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou 215153, PR China
| | - Jie Wang
- Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou 215153, PR China
| | - Zhidong Chang
- Suzhou Amazing Grace Medical Equipment Co., Ltd, Suzhou 215101, PR China
| | - Melvin Chun Yun Tan
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Kheng Loong Chong
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Chun Shiong Chong
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
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4
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Bing J, Guan Z, Zheng T, Ennis CL, Nobile CJ, Chen C, Chu H, Huang G. Rapid evolution of an adaptive multicellular morphology of Candida auris during systemic infection. Nat Commun 2024; 15:2381. [PMID: 38493178 PMCID: PMC10944540 DOI: 10.1038/s41467-024-46786-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/08/2024] [Indexed: 03/18/2024] Open
Abstract
Candida auris has become a serious threat to public health. The mechanisms of how this fungal pathogen adapts to the mammalian host are poorly understood. Here we report the rapid evolution of an adaptive C. auris multicellular aggregative morphology in the murine host during systemic infection. C. auris aggregative cells accumulate in the brain and exhibit obvious advantages over the single-celled yeast-form cells during systemic infection. Genetic mutations, specifically de novo point mutations in genes associated with cell division or budding processes, underlie the rapid evolution of this aggregative phenotype. Most mutated C. auris genes are associated with the regulation of cell wall integrity, cytokinesis, cytoskeletal properties, and cellular polarization. Moreover, the multicellular aggregates are notably more recalcitrant to the host antimicrobial peptides LL-37 and PACAP relative to the single-celled yeast-form cells. Overall, to survive in the host, C. auris can rapidly evolve a multicellular aggregative morphology via genetic mutations.
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Affiliation(s)
- Jian Bing
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438, China
| | - Zhangyue Guan
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Tianhong Zheng
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Craig L Ennis
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, Merced, CA, 95343, USA
| | - Clarissa J Nobile
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95343, USA
- Health Sciences Research Institute, University of California, Merced, Merced, CA, 95343, USA
| | - Changbin Chen
- The Center for Microbes, Development, and Health, Key Laboratory of Molecular Virology and Immunology, Unit of Pathogenic Fungal Infection & Host Immunity, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Haiqing Chu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China.
- Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China.
| | - Guanghua Huang
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.
- College of Pharmaceutical Sciences, Southwest University, Chongqing, 400716, China.
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5
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Gutzmann DJ, Kramer JJ, Toomey BM, Boone CHT, Atkin AL, Nickerson KW. Transcriptional regulation of the synthesis and secretion of farnesol in the fungus Candida albicans: examination of the Homann transcription regulator knockout collection. G3 (BETHESDA, MD.) 2023; 13:jkad172. [PMID: 37522561 PMCID: PMC10542173 DOI: 10.1093/g3journal/jkad172] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/01/2023]
Abstract
Candida albicans is an efficient colonizer of human gastrointestinal tracts and skin and is an opportunistic pathogen. C. albicans exhibits morphological plasticity, and the ability to switch between yeast and filamentous morphologies is associated with virulence. One regulator of this switch is the quorum sensing molecule farnesol that is produced by C. albicans throughout growth. However, the synthesis, secretion, regulation, and turnover of farnesol are not fully understood. To address this, we used our improved farnesol assay to screen a transcription regulator knockout library for differences in farnesol accumulation in whole cultures, pellets, and supernatants. All screened mutants produced farnesol and they averaged 9.2× more farnesol in the pellet than the supernatant. Nineteen mutants had significant differences with ten mutants producing more farnesol than their SN152+ wild-type control strain while nine produced less. Seven mutants exhibited greater secretion of farnesol while two exhibited less. We examined the time course for farnesol accumulation in six mutants with the greatest accumulation differences and found that those differences persisted throughout growth and they were not time dependent. Significantly, two high-accumulating mutants did not exhibit the decay in farnesol levels during stationary phase characteristic of wild-type C. albicans, suggesting that a farnesol modification/degradation mechanism is absent in these mutants. Identifying these transcriptional regulators provides new insight into farnesol's physiological functions regarding cell cycle progression, white-opaque switching, yeast-mycelial dimorphism, and response to cellular stress.
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Affiliation(s)
- Daniel J Gutzmann
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Jaxon J Kramer
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Brigid M Toomey
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Cory H T Boone
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Audrey L Atkin
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Kenneth W Nickerson
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
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6
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Younus Wani M, Saeed Saleh Alghamidi M, Srivastava V, Ahmad A, Aqlan FM, Saad Al-Bogami A. Click synthesis of pyrrolidine-based 1,2,3-triazole derivatives as antifungal agents causing cell cycle arrest and apoptosis in Candida auris. Bioorg Chem 2023; 136:106562. [PMID: 37119782 DOI: 10.1016/j.bioorg.2023.106562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 05/01/2023]
Abstract
The emergence of multidrug-resistant fungal pathogens such as Candida auris is one of the major reasons WHO has declared fungal infections as a public health threat. Multidrug resistance, high mortality rates, frequent misidentification, and involvement in hospital outbreaks of this fungus demand the development of novel therapeutic drugs. In this direction, we report the synthesis of novel pyrrolidine-based 1,2,3-triazole derivatives using Click Chemistry (CC) and evaluation of their antifungal susceptibility against C. auris following Clinical and Laboratory Standards Institute (CLSI) guidelines. The fungicidal activity of the most potent derivative (P6) was further quantitatively confirmed by the MUSE cell viability assay. For insight mechanisms, the effect of the most active derivative on cell cycle arrest was studied using MuseTM Cell Analyzer and apoptotic mode of cell death was determined by studying phosphatidylserine externalization and mitochondrial depolarization. In vitro susceptibility testing and viability assays showed that all the newly synthesized compounds have antifungal activity with P6 being the most potent derivative. Cell cycle analysis revealed that P6 arrested the cells in S-phase in a concentration dependent manner and the apoptotic mode of cell death was confirmed by the movement of cytochrome c from mitochondria to cytosol with membrane depolarization. The hemolytic assay confirmed the safe use of P6 for further in vivo studies.
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Affiliation(s)
- Mohmmad Younus Wani
- Department of Chemistry, College of Science, University of Jeddah, 21589 Jeddah, Saudi Arabia.
| | | | - Vartika Srivastava
- Department of Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, South Africa
| | - Aijaz Ahmad
- Department of Clinical Microbiology and Infectious Diseases, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, South Africa; Infection Control, Charlotte Maxeke Johannesburg Academic Hospital National Health Laboratory Service, South Africa
| | - Faisal M Aqlan
- Department of Chemistry, College of Science, University of Jeddah, 21589 Jeddah, Saudi Arabia
| | - Abdullah Saad Al-Bogami
- Department of Chemistry, College of Science, University of Jeddah, 21589 Jeddah, Saudi Arabia
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7
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Prasad P, Tippana M. Morphogenic plasticity: the pathogenic attribute of Candida albicans. Curr Genet 2023; 69:77-89. [PMID: 36947241 DOI: 10.1007/s00294-023-01263-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 02/10/2023] [Accepted: 02/20/2023] [Indexed: 03/23/2023]
Abstract
Candida albicans is a commensal organism of the human gastrointestinal tract and a prevalent opportunistic pathogen. It exhibits different morphogenic forms to survive in different host niches with distinct environmental conditions (pH, temperature, oxidative stress, nutrients, serum, chemicals, radiation, etc.) and genetic factors (transcription factors and genes). The different morphogenic forms of C. albicans are yeast, hyphal, pseudohyphal, white, opaque, and transient gray cells, planktonic and biofilm forms of cells. These forms differ in the parameters like cellular phenotype, colony morphology, adhesion to solid surfaces, gene expression profile, and the virulent traits. Each form is functionally distinct and responds discretely to the host immune system and antifungal drugs. Hence, morphogenic plasticity is the key to virulence. In this review, we address the characteristics, the pathogenic potential of the different morphogenic forms and the conditions required for morphogenic transitions.
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Affiliation(s)
- Priya Prasad
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, India.
| | - Meena Tippana
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, India
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8
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Lee Y, Hossain S, MacAlpine J, Robbins N, Cowen LE. Functional genomic analysis of Candida albicans protein kinases reveals modulators of morphogenesis in diverse environments. iScience 2023; 26:106145. [PMID: 36879823 PMCID: PMC9984565 DOI: 10.1016/j.isci.2023.106145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 12/21/2022] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Candida albicans is a leading cause of mycotic infection. The ability to transition between yeast and filamentous forms is critical to C. albicans virulence and complex signaling pathways regulate this process. Here, we screened a C. albicans protein kinase mutant library in six environmental conditions to identify regulators of morphogenesis. We identified the uncharacterized gene orf19.3751 as a negative regulator of filamentation and follow-up investigations implicated a role for orf19.3751 in cell cycle regulation. We also uncovered a dual role for the kinases Ire1 and protein kinase A (Tpk1 and Tpk2) in C. albicans morphogenesis, specifically as negative regulators of wrinkly colony formation on solid medium but positive regulators of filamentation in liquid medium. Further analyses suggested Ire1 modulates morphogenesis in both media states in part through the transcription factor Hac1 and in part through independent mechanisms. Overall, this work provides insights into the signaling governing morphogenesis in C. albicans.
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Affiliation(s)
- Yunjin Lee
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Saif Hossain
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jessie MacAlpine
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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9
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Jaitly P, Legrand M, Das A, Patel T, Chauvel M, Maufrais C, d’Enfert C, Sanyal K. A phylogenetically-restricted essential cell cycle progression factor in the human pathogen Candida albicans. Nat Commun 2022; 13:4256. [PMID: 35869076 PMCID: PMC9307598 DOI: 10.1038/s41467-022-31980-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 07/13/2022] [Indexed: 12/14/2022] Open
Abstract
Chromosomal instability caused by cell division errors is associated with antifungal drug resistance in fungal pathogens. Here, we identify potential mechanisms underlying such instability by conducting an overexpression screen monitoring chromosomal stability in the human fungal pathogen Candida albicans. Analysis of ~1000 genes uncovers six chromosomal stability (CSA) genes, five of which are related to cell division genes of other organisms. The sixth gene, CSA6, appears to be present only in species belonging to the CUG-Ser clade, which includes C. albicans and other human fungal pathogens. The protein encoded by CSA6 localizes to the spindle pole bodies, is required for exit from mitosis, and induces a checkpoint-dependent metaphase arrest upon overexpression. Thus, Csa6 is an essential cell cycle progression factor that is restricted to the CUG-Ser fungal clade, and could therefore be explored as a potential antifungal target. Chromosomal instability caused by cell division errors is associated with antifungal drug resistance in fungal pathogens. Here, Jaitly et al. identify several genes involved in chromosomal stability in Candida albicans, including a phylogenetically restricted gene encoding an essential cell-cycle progression factor.
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10
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Jung KW, Kwon S, Jung JH, Bahn YS. Essential Roles of Ribonucleotide Reductases under DNA Damage and Replication Stresses in Cryptococcus neoformans. Microbiol Spectr 2022; 10:e0104422. [PMID: 35736239 PMCID: PMC9431586 DOI: 10.1128/spectrum.01044-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/30/2022] [Indexed: 12/03/2022] Open
Abstract
A balance in the deoxyribonucleotide (dNTPs) intracellular concentration is critical for the DNA replication and repair processes. In the model yeast Saccharomyces cerevisiae, the Mec1-Rad53-Dun1 kinase cascade mainly regulates the ribonucleotide reductase (RNR) gene expression during DNA replication and DNA damage stress. However, the RNR regulatory mechanisms in basidiomycete fungi during DNA replication and damage stress remain elusive. Here, we observed that in C. neoformans, RNR1 (large RNR subunit) and RNR21 (one small RNR subunit) were required for cell viability, but not RNR22 (another small RNR subunit). RNR22 overexpression compensated for the lethality of RNR21 suppression. In contrast to the regulatory mechanisms of RNRs in S. cerevisiae, Rad53 and Chk1 kinases cooperatively or divergently controlled RNR1 and RNR21 expression under DNA damage and DNA replication stress. In particular, this study revealed that Chk1 mainly regulated RNR1 expression during DNA replication stress, whereas Rad53, rather than Chk1, played a significant role in controlling the expression of RNR21 during DNA damage stress. Furthermore, the expression of RNR22, not but RNR1 and RNR21, was suppressed by the Ssn6-Tup1 complex during DNA replication stress. Notably, we observed that RNR1 expression was mainly regulated by Mbs1, whereas RNR21 expression was cooperatively controlled by Mbs1 and Bdr1 as downstream factors of Rad53 and Chk1 during DNA replication and damage stress. Collectively, the regulation of RNRs in C. neoformans has both evolutionarily conserved and divergent features in DNA replication and DNA damage stress, compared with other yeasts. IMPORTANCE Upon DNA replication or damage stresses, it is critical to provide proper levels of deoxynucleotide triphosphates (dNTPs) and activate DNA repair machinery. Ribonucleotide reductases (RNRs), which are composed of large and small subunits, are required for synthesizing dNTP. An imbalance in the intracellular concentration of dNTPs caused by the perturbation of RNR results in a reduction in DNA repair fidelity. Despite the importance of their roles, functions and regulations of RNR have not been elucidated in the basidiomycete fungi. In this study, we found that the roles of RNR1, RNR21, and RNR22 genes encoding RNR subunits in the viability of C. neoformans. Furthermore, their expression levels are divergently regulated by the Rad53-Chk1 pathway and the Ssn6-Tup1 complex in response to DNA replication and damage stresses. Therefore, this study provides insight into the regulatory mechanisms of RNR genes to DNA replication and damage stresses in basidiomycete fungi.
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Affiliation(s)
- Kwang-Woo Jung
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
| | - Sunhak Kwon
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Jong-Hyun Jung
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Science and Technology, University of Science and Technology, Daejeon, Republic of Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
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11
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Hunter B, Benoit MPMH, Asenjo AB, Doubleday C, Trofimova D, Frazer C, Shoukat I, Sosa H, Allingham JS. Kinesin-8-specific loop-2 controls the dual activities of the motor domain according to tubulin protofilament shape. Nat Commun 2022; 13:4198. [PMID: 35859148 PMCID: PMC9300613 DOI: 10.1038/s41467-022-31794-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022] Open
Abstract
Kinesin-8s are dual-activity motor proteins that can move processively on microtubules and depolymerize microtubule plus-ends, but their mechanism of combining these distinct activities remains unclear. We addressed this by obtaining cryo-EM structures (2.6-3.9 Å) of Candida albicans Kip3 in different catalytic states on the microtubule lattice and on a curved microtubule end mimic. We also determined a crystal structure of microtubule-unbound CaKip3-ADP (2.0 Å) and analyzed the biochemical activity of CaKip3 and kinesin-1 mutants. These data reveal that the microtubule depolymerization activity of kinesin-8 originates from conformational changes of its motor core that are amplified by dynamic contacts between its extended loop-2 and tubulin. On curved microtubule ends, loop-1 inserts into preceding motor domains, forming head-to-tail arrays of kinesin-8s that complement loop-2 contacts with curved tubulin and assist depolymerization. On straight tubulin protofilaments in the microtubule lattice, loop-2-tubulin contacts inhibit conformational changes in the motor core, but in the ADP-Pi state these contacts are relaxed, allowing neck-linker docking for motility. We propose that these tubulin shape-induced alternations between pro-microtubule-depolymerization and pro-motility kinesin states, regulated by loop-2, are the key to the dual activity of kinesin-8 motors.
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Affiliation(s)
- Byron Hunter
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Matthieu P M H Benoit
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ana B Asenjo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Caitlin Doubleday
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Daria Trofimova
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Corey Frazer
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912, USA
| | - Irsa Shoukat
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Hernando Sosa
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - John S Allingham
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada.
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12
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Blocking Polyphosphate Mobilization Inhibits Pho4 Activation and Virulence in the Pathogen Candida albicans. mBio 2022; 13:e0034222. [PMID: 35575514 PMCID: PMC9239153 DOI: 10.1128/mbio.00342-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The ability of pathogenic fungi to obtain essential nutrients from the host is vital for virulence. In Candida albicans, acquisition of the macronutrient phosphate is regulated by the Pho4 transcription factor and is important for both virulence and resistance to host-encountered stresses. All cells store phosphate in the form of polyphosphate (polyP), a ubiquitous polymer comprising tens to hundreds of phosphate residues. Release of phosphate from polyP is one of the first responses evoked in response to phosphate starvation, and here, we sought to explore the importance of polyP mobilization in the pathobiology of C. albicans. We found that two polyphosphatases, Ppn1 and Ppx1, function redundantly to release phosphate from polyP in C. albicans. Strikingly, we reveal that blocking polyP mobilization prevents the activation of the Pho4 transcription factor: following Pi starvation, Pho4 fails to accumulate in the nucleus and induce Pi acquisition genes in ppn1Δ ppx1Δ cells. Consequently, ppn1Δ ppx1Δ cells display impaired resistance to the same range of stresses that require Pho4 for survival. In addition, cells lacking both polyphosphatases are exquisitely sensitive to DNA replication stress, indicating that polyP mobilization is needed to support the phosphate-demanding process of DNA replication. Blocking polyP mobilization also results in significant morphological defects, as ppn1Δ ppx1Δ cells form large pseudohypha-like cells that are resistant to serum-induced hypha formation. Thus, polyP mobilization impacts key processes important for the pathobiology of C. albicans, and consistent with this, we found that blocking this process attenuates the virulence of this important human fungal pathogen.
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13
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Prasad P, Joshi A, Ghosh SK. Sth1, the ATPase subunit of the RSC chromatin remodeler has important roles in stress response and DNA damage repair in the pathogenic fungi Candida albicans. Microb Pathog 2022; 166:105515. [DOI: 10.1016/j.micpath.2022.105515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/26/2022] [Accepted: 04/03/2022] [Indexed: 01/13/2023]
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14
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Rashid S, Correia-Mesquita TO, Godoy P, Omran RP, Whiteway M. SAGA Complex Subunits in Candida albicans Differentially Regulate Filamentation, Invasiveness, and Biofilm Formation. Front Cell Infect Microbiol 2022; 12:764711. [PMID: 35350439 PMCID: PMC8957876 DOI: 10.3389/fcimb.2022.764711] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 02/11/2022] [Indexed: 11/24/2022] Open
Abstract
SAGA (Spt-Ada-Gcn5-acetyltransferase) is a highly conserved, multiprotein co-activator complex that consists of five distinct modules. It has two enzymatic functions, a histone acetyltransferase (HAT) and a deubiquitinase (DUB) and plays a central role in processes such as transcription initiation, elongation, protein stability, and telomere maintenance. We analyzed conditional and null mutants of the SAGA complex module components in the fungal pathogen Candida albicans; Ngg1, (the HAT module); Ubp8, (the DUB module); Tra1, (the recruitment module), Spt7, (the architecture module) and Spt8, (the TBP interaction unit), and assessed their roles in a variety of cellular processes. We observed that spt7Δ/Δ and spt8Δ/Δ strains have a filamentous phenotype, and both are highly invasive in yeast growing conditions as compared to the wild type, while ngg1Δ/Δ and ubp8Δ/Δ are in yeast-locked state and non-invasive in both YPD media and filamentous induced conditions compared to wild type. RNA-sequencing-based transcriptional profiling of SAGA mutants reveals upregulation of hyphal specific genes in spt7Δ/Δ and spt8Δ/Δ strains and downregulation of ergosterol metabolism pathway. As well, spt7Δ/Δ and spt8Δ/Δ confer susceptibility to antifungal drugs, to acidic and alkaline pH, to high temperature, and to osmotic, oxidative, cell wall, and DNA damage stresses, indicating that these proteins are important for genotoxic and cellular stress responses. Despite having similar morphological phenotypes (constitutively filamentous and invasive) spt7 and spt8 mutants displayed variation in nuclear distribution where spt7Δ/Δ cells were frequently binucleate and spt8Δ/Δ cells were consistently mononucleate. We also observed that spt7Δ/Δ and spt8Δ/Δ mutants were quickly engulfed by macrophages compared to ngg1Δ/Δ and ubp8Δ/Δ strains. All these findings suggest that the SAGA complex modules can have contrasting functions where loss of Spt7 or Spt8 enhances filamentation and invasiveness while loss of Ngg1 or Ubp8 blocks these processes.
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Affiliation(s)
| | | | | | | | - Malcolm Whiteway
- Department of Biology, Concordia University, Montreal, QC, Canada
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15
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Yao S, Feng Y, Zhang Y, Feng J. DNA damage checkpoint and repair: From the budding yeast Saccharomyces cerevisiae to the pathogenic fungus Candida albicans. Comput Struct Biotechnol J 2021; 19:6343-6354. [PMID: 34938410 PMCID: PMC8645783 DOI: 10.1016/j.csbj.2021.11.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 01/09/2023] Open
Abstract
Cells are constantly challenged by internal or external genotoxic assaults, which may induce a high frequency of DNA lesions, leading to genome instability. Accumulation of damaged DNA is severe or even lethal to cells and can result in abnormal proliferation that can cause cancer in multicellular organisms, aging or cell death. Eukaryotic cells have evolved a comprehensive defence system termed the DNA damage response (DDR) to monitor and remove lesions in their DNA. The DDR has been extensively studied in the budding yeast Saccharomyces cerevisiae. Emerging evidence indicates that DDR genes in the pathogenic fungus Candida albicans show functional consistency with their orthologs in S. cerevisiae, but may act through distinct mechanisms. In particular, the DDR in C. albicans appears critical for resisting DNA damage stress induced by reactive oxygen species (ROS) produced from immune cells, and this plays a vital role in pathogenicity. Therefore, DDR genes could be considered as potential targets for clinical therapies. This review summarizes the identified DNA damage checkpoint and repair genes in C. albicans based on their orthologs in S. cerevisiae, and discusses their contribution to pathogenicity in C. albicans.
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Affiliation(s)
- Shuangyan Yao
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
- Nantong Health College of Jiangsu Province, Nantong 226016, Jiangsu, China
| | - Yuting Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
| | - Yan Zhang
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
| | - Jinrong Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
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16
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Chow EWL, Pang LM, Wang Y. From Jekyll to Hyde: The Yeast-Hyphal Transition of Candida albicans. Pathogens 2021; 10:pathogens10070859. [PMID: 34358008 PMCID: PMC8308684 DOI: 10.3390/pathogens10070859] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/22/2022] Open
Abstract
Candida albicans is a major fungal pathogen of humans, accounting for 15% of nosocomial infections with an estimated attributable mortality of 47%. C. albicans is usually a benign member of the human microbiome in healthy people. Under constant exposure to highly dynamic environmental cues in diverse host niches, C. albicans has successfully evolved to adapt to both commensal and pathogenic lifestyles. The ability of C. albicans to undergo a reversible morphological transition from yeast to filamentous forms is a well-established virulent trait. Over the past few decades, a significant amount of research has been carried out to understand the underlying regulatory mechanisms, signaling pathways, and transcription factors that govern the C. albicans yeast-to-hyphal transition. This review will summarize our current understanding of well-elucidated signal transduction pathways that activate C. albicans hyphal morphogenesis in response to various environmental cues and the cell cycle machinery involved in the subsequent regulation and maintenance of hyphal morphogenesis.
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Affiliation(s)
- Eve Wai Ling Chow
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
| | - Li Mei Pang
- National Dental Centre Singapore, National Dental Research Institute Singapore (NDRIS), 5 Second Hospital Ave, Singapore 168938, Singapore;
| | - Yue Wang
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
- Correspondence:
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17
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Germination of a Field: Women in Candida albicans Research. CURRENT CLINICAL MICROBIOLOGY REPORTS 2021. [DOI: 10.1007/s40588-021-00169-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Duan X, Chen X, Wang K, Chen L, Glomb O, Johnsson N, Feng L, Zhou XQ, Bi E. Essential role of the endocytic site-associated protein Ecm25 in stress-induced cell elongation. Cell Rep 2021; 35:109122. [PMID: 34010635 PMCID: PMC8202958 DOI: 10.1016/j.celrep.2021.109122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 02/16/2021] [Accepted: 04/22/2021] [Indexed: 11/27/2022] Open
Abstract
How cells adopt a different morphology to cope with stress is not well understood. Here, we show that budding yeast Ecm25 associates with polarized endocytic sites and interacts with the polarity regulator Cdc42 and several late-stage endocytic proteins via distinct regions, including an actin filament-binding motif. Deletion of ECM25 does not affect Cdc42 activity or cause any strong defects in fluid-phase and clathrin-mediated endocytosis but completely abolishes hydroxyurea-induced cell elongation. This phenotype is accompanied by depolarization of the spatiotemporally coupled exo-endocytosis in the bud cortex while maintaining the overall mother-bud polarity. These data suggest that Ecm25 provides an essential link between the polarization signal and the endocytic machinery to enable adaptive morphogenesis under stress conditions. How cells adopt a different morphology to cope with stress is not well understood. Duan et al. report that the budding yeast protein Ecm25 plays an essential role in stress-induced cell elongation by linking the polarity regulator Cdc42 to the late-stage endocytic machinery.
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Affiliation(s)
- Xudong Duan
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan, China; Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Kangji Wang
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Li Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Oliver Glomb
- Institut für Molekulare Genetik und Zellbiologie, Universität Ulm, 89081 Ulm, Germany
| | - Nils Johnsson
- Institut für Molekulare Genetik und Zellbiologie, Universität Ulm, 89081 Ulm, Germany
| | - Lin Feng
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan, China
| | - Xiao-Qiu Zhou
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130 Sichuan, China.
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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19
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Wang Y, Wang N, Liu J, Zhang Y, Li X, Han Q. Homolog of Saccharomyces cerevisiae SLX4 is required for cell recovery from MMS-induced DNA damage in Candida albicans. FEMS Yeast Res 2021; 21:6145020. [PMID: 33606011 DOI: 10.1093/femsyr/foab010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/17/2021] [Indexed: 01/02/2023] Open
Abstract
SLX4 is a scaffold to coordinate the action of structure-specific endonucleases that are required for homologous recombination and DNA repair. In view of ScSLX4 functions in the maintenance and stability of the genome in Saccharomyces cerevisiae, we have explored the roles of CaSLX4 in Candida albicans. Here, we constructed slx4Δ/Δ mutant and found that it exhibited increased sensitivity to the DNA damaging agent, methyl methanesulfonate (MMS) but not the DNA replication inhibitor, hydroxyurea (HU). Accordingly, RT-qPCR and western blotting analysis revealed the activation of SLX4 expression in response to MMS. The deletion of SLX4 resulted in a defect in the recovery from MMS-induced filamentation to yeast form and re-entry into the cell cycle. Like many other DNA repair genes, SLX4 expression was activated by the checkpoint kinase Rad53 under MMS-induced DNA damage. In addition, SLX4 was not required for the inactivation of the DNA damage checkpoint, as indicated by normal phosphorylation of Rad53 in slx4Δ/Δ cells. Therefore, our results demonstrate SLX4 plays an important role in cell recovery from MMS-induced DNA damage in C. albicans.
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Affiliation(s)
- Yueqing Wang
- Medical College, China Three Gorges University, Yichang 443002, China
| | - Na Wang
- The Second High School Attached to Beijing Normal University, Beijing 100088, China
| | - Jia Liu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Yaxuan Zhang
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Xiaojiaoyang Li
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Qi Han
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China
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20
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Hossain S, Lash E, Veri AO, Cowen LE. Functional connections between cell cycle and proteostasis in the regulation of Candida albicans morphogenesis. Cell Rep 2021; 34:108781. [PMID: 33626353 PMCID: PMC7971348 DOI: 10.1016/j.celrep.2021.108781] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/18/2020] [Accepted: 02/02/2021] [Indexed: 02/06/2023] Open
Abstract
Morphological plasticity is a key virulence trait for many fungal pathogens. For the opportunistic fungal pathogen Candida albicans, transitions among yeast, pseudohyphal, and hyphal forms are critical for virulence, because the morphotypes play distinct roles in the infection process. C. albicans morphogenesis is induced in response to many host-relevant conditions and is regulated by complex signaling pathways and cellular processes. Perturbation of either cell-cycle progression or protein homeostasis induces C. albicans filamentation, demonstrating that these processes play a key role in morphogenetic control. Regulators such as cyclin-dependent kinases, checkpoint proteins, the proteasome, the heat shock protein Hsp90, and the heat shock transcription factor Hsf1 all influence morphogenesis, often through interconnected effects on the cell cycle and proteostasis. This review highlights the major cell-cycle and proteostasis regulators that modulate morphogenesis and discusses how these two processes intersect to regulate this key virulence trait.
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Affiliation(s)
- Saif Hossain
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Emma Lash
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Amanda O Veri
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1M1, Canada.
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21
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Xie Y, Loh ZY, Xue J, Zhou F, Sun J, Qiao Z, Jin S, Deng Y, Li H, Wang Y, Lu L, Gao Y, Miao Y. Orchestrated actin nucleation by the Candida albicans polarisome complex enables filamentous growth. J Biol Chem 2020; 295:14840-14854. [PMID: 32848016 DOI: 10.1074/jbc.ra120.013890] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/09/2020] [Indexed: 12/29/2022] Open
Abstract
Candida albicans is a dimorphic fungus that converts from a yeast form to a hyphae form during infection. This switch requires the formation of actin cable to coordinate polarized cell growth. It's known that nucleation of this cable requires a multiprotein complex localized at the tip called the polarisome, but the mechanisms underpinning this process were unclear. Here, we found that C. albicans Aip5, a homolog of polarisome component ScAip5 in Saccharomyces cerevisiae that nucleates actin polymerization and synergizes with the formin ScBni1, regulates actin assembly and hyphae growth synergistically with other polarisome proteins Bni1, Bud6, and Spa2. The C terminus of Aip5 binds directly to G-actin, Bni1, and the C-terminal of Bud6, which form the core of the nucleation complex to polymerize F-actin. Based on insights from structural biology and molecular dynamic simulations, we propose a possible complex conformation of the actin nucleation core, which provides cooperative positioning and supports the synergistic actin nucleation activity of a tri-protein complex Bni1-Bud6-Aip5. Together with known interactions of Bni1 with Bud6 and Aip5 in S. cerevisiae, our findings unravel molecular mechanisms of C. albicans by which the tri-protein complex coordinates the actin nucleation in actin cable assembly and hyphal growth, which is likely a conserved mechanism in different filamentous fungi and yeast.
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Affiliation(s)
- Ying Xie
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Zhi Yang Loh
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jiao Xue
- School of Biological Sciences, Nanyang Technological University, Singapore; College of Life Science and Technology, Jinan University, Guangzhou, China; The College of Life Sciences, Northwest University, Xi'an, China
| | - Feng Zhou
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jialin Sun
- School of Biological Sciences, Nanyang Technological University, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore
| | - Zhu Qiao
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Shengyang Jin
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yinyue Deng
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Guangzhou, China
| | - Hongye Li
- College of Life Science and Technology, Jinan University, Guangzhou, China
| | - Yue Wang
- Institute of Molecular and Cell Biology, A*STAR, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Yonggui Gao
- School of Biological Sciences, Nanyang Technological University, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore; NTU Institute of Structural Biology, Nanyang Technological University, Nanyang Drive, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore.
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22
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Pseudohyphal Growth of the Emerging Pathogen Candida auris Is Triggered by Genotoxic Stress through the S Phase Checkpoint. mSphere 2020; 5:5/2/e00151-20. [PMID: 32161147 PMCID: PMC7067593 DOI: 10.1128/msphere.00151-20] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Candida auris is a newly emerged fungal pathogen of humans. This species was first reported in 2009 when it was identified in an ear infection of a patient in Japan. However, despite intense interest in this organism as an often multidrug-resistant fungus, there is little knowledge about its cellular biology. During infection of human patients, fungi are able to change cell shape from ellipsoidal yeast cells to elongated filaments to adapt to various conditions within the host organism. There are different types of filaments, which are triggered by reactions to different cues. Candida auris fails to form filaments when exposed to triggers that stimulate yeast filament morphogenesis in other fungi. Here, we show that it does form filaments when its DNA is damaged. These conditions might arise when Candida auris cells interact with host immune cells or during growth in certain host tissues (kidney or bladder) or during treatment with antifungal drugs. The morphogenetic switching between yeast cells and filaments (true hyphae and pseudohyphae) is a key cellular feature required for full virulence in many polymorphic fungal pathogens, such as Candida albicans. In the recently emerged yeast pathogen Candida auris, occasional elongation of cells has been reported. However, environmental conditions and genetic triggers for filament formation have remained elusive. Here, we report that induction of DNA damage and perturbation of replication forks by treatment with genotoxins, such as hydroxyurea, methyl methanesulfonate, and the clinically relevant fungistatic 5-fluorocytosine, cause filamentation in C. auris. The filaments formed were characteristic of pseudohyphae and not parallel-sided true hyphae. Pseudohyphal growth is apparently signaled through the S phase checkpoint and, interestingly, is Tup1 independent in C. auris. Intriguingly, the morphogenetic switching capability is strain specific in C. auris, highlighting the heterogenous nature of the species as a whole. IMPORTANCECandida auris is a newly emerged fungal pathogen of humans. This species was first reported in 2009 when it was identified in an ear infection of a patient in Japan. However, despite intense interest in this organism as an often multidrug-resistant fungus, there is little knowledge about its cellular biology. During infection of human patients, fungi are able to change cell shape from ellipsoidal yeast cells to elongated filaments to adapt to various conditions within the host organism. There are different types of filaments, which are triggered by reactions to different cues. Candida auris fails to form filaments when exposed to triggers that stimulate yeast filament morphogenesis in other fungi. Here, we show that it does form filaments when its DNA is damaged. These conditions might arise when Candida auris cells interact with host immune cells or during growth in certain host tissues (kidney or bladder) or during treatment with antifungal drugs.
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23
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Sparapani S, Bachewich C. Characterization of a novel separase-interacting protein and candidate new securin, Eip1p, in the fungal pathogen Candida albicans. Mol Biol Cell 2019; 30:2469-2489. [PMID: 31411946 PMCID: PMC6743357 DOI: 10.1091/mbc.e18-11-0696] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 07/03/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022] Open
Abstract
Proper chromosome segregation is crucial for maintaining genomic stability and dependent on separase, a conserved and essential cohesin protease. Securins are key regulators of separases, but remain elusive in many organisms due to sequence divergence. Here, we demonstrate that the separase homologue Esp1p in the ascomycete Candida albicans, an important pathogen of humans, is essential for chromosome segregation. However, C. albicans lacks a sequence homologue of securins found in model ascomycetes. We sought a functional homologue through identifying Esp1p interacting factors. Affinity purification of Esp1p and mass spectrometry revealed Esp1p-Interacting Protein1 (Eip1p)/Orf19.955p, an uncharacterized protein specific to Candida species. Functional analyses demonstrated that Eip1p is important for chromosome segregation but not essential, and modulated in an APCCdc20-dependent manner, similar to securins. Eip1p is strongly enriched in response to methyl methanesulfate (MMS) or hydroxyurea (HU) treatment, and its depletion partially suppresses an MMS or HU-induced metaphase block. Further, Eip1p depletion reduces Mcd1p/Scc1p, a cohesin subunit and separase target. Thus, Eip1p may function as a securin. However, other defects in Eip1p-depleted cells suggest additional roles. Overall, the results introduce a candidate new securin, provide an approach for identifying these divergent proteins, reveal a putative anti-fungal therapeutic target, and highlight variations in mitotic regulation in eukaryotes.
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Affiliation(s)
- Samantha Sparapani
- Department of Biology, Concordia University, Montreal, QC H4B 1R6, Canada
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24
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Prasad P, Sanyal K, Ghosh SK. Sth1, the Key Subunit of the RSC Chromatin Remodeling Complex, Is Essential in Maintaining Chromosomal Integrity and Mediating High Fidelity Chromosome Segregation in the Human Fungal Pathogen Candida albicans. Front Microbiol 2019; 10:1303. [PMID: 31249561 PMCID: PMC6582774 DOI: 10.3389/fmicb.2019.01303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 05/27/2019] [Indexed: 12/20/2022] Open
Abstract
Chromatin architecture influences gene expression and makes specialized chromatin domains. Factors including histone variants, histone modifiers and chromatin remodelers that define chromatin architecture impact chromosome related processes in Candida albicans. In this context, we sought to investigate the roles of the ATP-dependent chromatin remodeler, Remodel the Structure of Chromatin (RSC) in chromosome segregation of C. albicans. Sth1 is the key ATPase component of RSC and has profound roles in different cellular processes in Saccharomyces cerevisiae. We demonstrate that STH1 is an essential gene in C. albicans. The depletion of Sth1 induces pseudohyphal cells, abnormal spindle morphology, sensitivity toward anti-mitotic drugs and global cohesion defect suggesting an important role of Sth1 in kinetochore-microtubule related processes in C. albicans. Strikingly, Sth1 is required to maintain clustered kinetochores revealing the fact that RSC is required in kinetochore integrity. Taken together, we show that RSC plays an important role in various chromatin-templated processes including chromosome segregation in C. albicans.
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Affiliation(s)
- Priya Prasad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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Legrand M, Jaitly P, Feri A, d'Enfert C, Sanyal K. Candida albicans: An Emerging Yeast Model to Study Eukaryotic Genome Plasticity. Trends Genet 2019; 35:292-307. [PMID: 30826131 DOI: 10.1016/j.tig.2019.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 01/07/2023]
Abstract
Saccharomyces cerevisiae and Schizosaccharomyces pombe have served as uncontested unicellular model organisms, as major discoveries made in the field of genome biology using yeast genetics have proved to be relevant from yeast to humans. The yeast Candida albicans has attracted much attention because of its ability to switch between a harmless commensal and a dreaded human pathogen. C. albicans bears unique features regarding its life cycle, genome structure, and dynamics, and their links to cell biology and adaptation to environmental challenges. Examples include a unique reproduction cycle with haploid, diploid, and tetraploid forms; a distinctive organisation of chromosome hallmarks; a highly dynamic genome, with extensive karyotypic variations, including aneuploidies, isochromosome formation, and loss-of-heterozygosity; and distinctive links between the response to DNA alterations and cell morphology. These features have made C. albicans emerge as a new and attractive unicellular model to study genome biology and dynamics in eukaryotes.
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Affiliation(s)
- Mélanie Legrand
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France
| | - Priya Jaitly
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Adeline Feri
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France; Current address: Pathoquest, BioPark, 11 rue Watt, 75013 Paris, France
| | - Christophe d'Enfert
- Fungal Biology and Pathogenicity Unit, Department of Mycology, Institut Pasteur, INRA, Paris, France.
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India.
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Regulation of Candida albicans Hyphal Morphogenesis by Endogenous Signals. J Fungi (Basel) 2019; 5:jof5010021. [PMID: 30823468 PMCID: PMC6463138 DOI: 10.3390/jof5010021] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 12/15/2022] Open
Abstract
Candida albicans is a human commensal fungus that is able to assume several morphologies, including yeast, hyphal, and pseudohyphal. Under a range of conditions, C. albicans performs a regulated switch to the filamentous morphology, characterized by the emergence of a germ tube from the yeast cell, followed by a mold-like growth of branching hyphae. This transition from yeast to hyphal growth has attracted particular attention, as it has been linked to the virulence of C. albicans as an opportunistic human pathogen. Signal transduction pathways that mediate the induction of the hyphal transcription program upon the imposition of external stimuli have been extensively investigated. However, the hyphal morphogenesis transcription program can also be induced by internal cellular signals, such as inhibition of cell cycle progression, and conversely, the inhibition of hyphal extension can repress hyphal-specific gene expression, suggesting that endogenous cellular signals are able to modulate hyphal gene expression as well. Here we review recent developments in the regulation of the hyphal morphogenesis of C. albicans, with emphasis on endogenous morphogenetic signals.
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Mms21: A Putative SUMO E3 Ligase in Candida albicans That Negatively Regulates Invasiveness and Filamentation, and Is Required for the Genotoxic and Cellular Stress Response. Genetics 2018; 211:579-595. [PMID: 30530734 DOI: 10.1534/genetics.118.301769] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 11/28/2018] [Indexed: 12/28/2022] Open
Abstract
In the life cycle of the fungal pathogen Candida albicans, the formation of filamentous cells is a differentiation process that is critically involved in host tissue invasion, and in adaptation to host cell and environmental stresses. Here, we have used the Gene Replacement And Conditional Expression library to identify genes controlling invasiveness and filamentation; conditional repression of the library revealed 69 mutants that triggered these processes. Intriguingly, the genes encoding the small ubiquitin-like modifier (SUMO) E3 ligase Mms21, and all other tested members of the sumoylation pathway, were both nonessential and capable of triggering filamentation upon repression, suggesting an important role for sumoylation in controlling filamentation in C. albicans We have investigated Mms21 in detail. Both Mms21 nulls (mms21Δ/Δ) and SP [Siz/Pias (protein inhibitor of activated signal transducer and activator of transcription)] domain (SUMO E3 ligase domain)-deleted mutants displayed invasiveness, filamentation, and abnormal nuclear segregation; filament formation occurred even in the absence of the hyphal transcription factor Efg1. Transcriptional analysis of mms21Δ/Δ showed an increase in expression from two- to eightfold above that of the wild-type for hyphal-specific genes, including ECE1, PGA13, PGA26, HWP1, ALS1, ALS3, SOD4, SOD5, UME6, and HGC1 The Mms21-deleted mutants were unable to recover from DNA-damaging agents like methyl methane sulfonate, hydroxyurea, hydrogen peroxide, and UV radiation, suggesting that the protein is important for genotoxic stress responses. In addition, the mms21Δ/Δ mutant displayed sensitivity to cell wall and thermal stresses, and to different antifungal drugs. All these findings suggest that Mms21 plays important roles in cellular differentiation, DNA damage and cellular stress responses, and in response to antifungal drugs.
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Manohar K, Peroumal D, Acharya N. TLS dependent and independent functions of DNA polymerase eta (Polη/Rad30) from Pathogenic Yeast Candida albicans. Mol Microbiol 2018; 110:707-727. [PMID: 29907984 DOI: 10.1111/mmi.14004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 06/03/2018] [Accepted: 06/06/2018] [Indexed: 02/06/2023]
Abstract
Polη, a unique TLS DNA polymerase that promotes efficient bypass of UV-induced CPDs and cisplatin adducts, has not been explored in Candida species yet. Here, we show that CaPolη plays a vital role in protecting Candida albicans genome from diverse array of DNA damaging agents, not limited to UV and cisplatin. Polη deficient strain did not exhibit any hyphal development in the presence of UV and cisplatin while the wild type strain profusely developed DNA damage induced filamentation. The polarized growth induced by HU and MMS was found to be Polη independent. No common regulatory pathway of morphogenesis operates in C. albicans due to genomic stress, rather Polη branches away from RAD53 dependent pathway to be specific to UV/cisplatin. Interestingly, serum that does not inflict any DNA damage also induces hyphal growth in C. albicans, and requires a functionally active Polη. Importantly, deletion of RAD30 sensitized the strain to amphotericin B; but its presence resulted in azole drug tolerance only in DNA damaging conditions. We suggest that the roles of CaPolη in genome stability and genotoxins induced filamentation are due to its TLS activities; whereas its TLS independent functions play a vital role in serum induced morphogenesis and amphotericin B resistance.
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Affiliation(s)
- Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Doureradjou Peroumal
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
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Chen C, Zeng G, Wang Y. G1 and S phase arrest in Candida albicans induces filamentous growth via distinct mechanisms. Mol Microbiol 2018; 110:191-203. [PMID: 30084240 DOI: 10.1111/mmi.14097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 01/07/2023]
Abstract
Candida albicans is an opportunistic fungal pathogen. In immunocompromised individuals, it can cause bloodstream infections with high mortality rates. The ability to switch between yeast and hyphal morphologies is a critical virulence factor of C. albicans. In response to diverse environmental cues, several signaling pathways are activated resulting in filamentous growth. Interestingly, cell cycle arrest can also trigger filamentous growth although the pathways involved are not well-understood. Here, we demonstrate that the cAMP-PKA pathway is involved in the filamentous growth caused by G1 arrest due to the depletion of the G1 cyclin Cln3 and S phase arrest due to hydroxyurea treatment. The downstream mechanisms involved in filamentation are different between the two cell cycle arrest phenomena. Cln3-depleted cells require HGC1 and UME6 for filamentous growth, but hydroxyurea-induced filamentation does not. Also, the hyphal repressor Nrg1 is not involved in the suppression of Cln3-depletion and hydroxyurea-induced filamentous growth. The findings highlight the complexity of the signaling networks that control filamentous growth in which different mechanisms downstream of the cAMP-PKA pathway are activated based on the nature of the inducing signals.
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Affiliation(s)
- Cuilan Chen
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Guisheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Functions of CaPhm7 in the regulation of ion homeostasis, drug tolerance, filamentation and virulence in Candida albicans. BMC Microbiol 2018; 18:49. [PMID: 29866033 PMCID: PMC5987382 DOI: 10.1186/s12866-018-1193-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/21/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Calcium-permeable transient receptor potential (TRP) channels exist in eukaryotic cells from yeasts to animals and plants. and they act as sensors for various stresses. Arabidopsis thaliana calcium permeable stress-gated cation channel 1 (AtCSC1) was the first plant calcium-permeable TRP to be described and can be activated by hyperosmotic shock. Candida albicans CaPHM7 is one of the sequence homologs of AtCSC1, but its function remains unknown. RESULTS We show here that CaPhm7 is localized to the plasma membrane in both the yeast and hyphal cells of C. albicans. C. albicans cells lacking CaPHM7 are sensitive to SDS and ketoconazole but tolerant to rapamycin and zinc. In addition, deletion of CaPHM7 leads to a filamentation defect, reduced colony growth and attenuated virulence in the mouse model of systemic infection. CONCLUSIONS CaPhm7 is involved in the regulation of ion homeostasis, drug tolerance, filamentation and virulence in this important human fungal pathogen. CaPhm7 could be a potential target of antifungal drugs.
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Veri AO, Miao Z, Shapiro RS, Tebbji F, O’Meara TR, Kim SH, Colazo J, Tan K, Vyas VK, Whiteway M, Robbins N, Wong KH, Cowen LE. Tuning Hsf1 levels drives distinct fungal morphogenetic programs with depletion impairing Hsp90 function and overexpression expanding the target space. PLoS Genet 2018; 14:e1007270. [PMID: 29590106 PMCID: PMC5873724 DOI: 10.1371/journal.pgen.1007270] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/22/2018] [Indexed: 12/24/2022] Open
Abstract
The capacity to respond to temperature fluctuations is critical for microorganisms to survive within mammalian hosts, and temperature modulates virulence traits of diverse pathogens. One key temperature-dependent virulence trait of the fungal pathogen Candida albicans is its ability to transition from yeast to filamentous growth, which is induced by environmental cues at host physiological temperature. A key regulator of temperature-dependent morphogenesis is the molecular chaperone Hsp90, which has complex functional relationships with the transcription factor Hsf1. Although Hsf1 controls global transcriptional remodeling in response to heat shock, its impact on morphogenesis remains unknown. Here, we establish an intriguing paradigm whereby overexpression or depletion of C. albicans HSF1 induces morphogenesis in the absence of external cues. HSF1 depletion compromises Hsp90 function, thereby driving filamentation. HSF1 overexpression does not impact Hsp90 function, but rather induces a dose-dependent expansion of Hsf1 direct targets that drives overexpression of positive regulators of filamentation, including Brg1 and Ume6, thereby bypassing the requirement for elevated temperature during morphogenesis. This work provides new insight into Hsf1-mediated environmentally contingent transcriptional control, implicates Hsf1 in regulation of a key virulence trait, and highlights fascinating biology whereby either overexpression or depletion of a single cellular regulator induces a profound developmental transition. For human pathogens, the capacity to respond to elevated temperature is required for survival, with elevated temperature in the form of fever as a conserved host response to defend against infection. One of the leading fungal pathogens of humans in Candida albicans, which is capable of growing in both a yeast and filamentous state. The ability to transition between these forms is a key virulence trait, and one that is highly temperature-dependent. A pivotal regulator of filamentous growth is the temperature-responsive molecular chaperone Hsp90, which has complex relationships with the transcription factor Hsf1. Although Hsf1 regulates changes in gene expression in response to heat shock, its impact on morphogenesis remains unknown. Here, we uncover an intriguing phenomenon whereby overexpression or depletion of C. albicans HSF1 induces morphogenesis. We observe that HSF1 depletion compromises Hsp90 function, thereby driving filamentation. In contrast, HSF1 overexpression induces a dose-dependent expansion of its transcriptional targets that drives overexpression of positive regulators of filamentous growth. This work illuminates novel mechanisms through which tuning the levels of an environmentally contingent transcription factor drives a key developmental program.
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Affiliation(s)
- Amanda O. Veri
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Zhengqiang Miao
- Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Rebecca S. Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Faiza Tebbji
- Infectious Disease Research Centre, Université Laval, Quebec City, Quebec, Canada
| | - Teresa R. O’Meara
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Sang Hu Kim
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Juan Colazo
- Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kaeling Tan
- Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Valmik K. Vyas
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Malcolm Whiteway
- Department of Biology, Concordia University, Montréal, Quebec, Canada
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Koon Ho Wong
- Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Glory A, van Oostende CT, Geitmann A, Bachewich C. Depletion of the mitotic kinase Cdc5p in Candida albicans results in the formation of elongated buds that switch to the hyphal fate over time in a Ume6p and Hgc1p-dependent manner. Fungal Genet Biol 2017; 107:51-66. [DOI: 10.1016/j.fgb.2017.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/27/2017] [Accepted: 08/08/2017] [Indexed: 10/19/2022]
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Feng J, Duan Y, Qin Y, Sun W, Zhuang Z, Zhu D, Jiang L. The N-terminal pY33XL motif of CaPsy2 is critical for the function of protein phosphatase 4 in CaRad53 deactivation, DNA damage-induced filamentation and virulence in Candida albicans. Int J Med Microbiol 2017; 307:471-480. [PMID: 28967545 DOI: 10.1016/j.ijmm.2017.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 09/11/2017] [Accepted: 09/19/2017] [Indexed: 11/25/2022] Open
Abstract
Protein phosphatase PP4 is composed of one catalytic subunit and one or two regulatory subunits and conserved in eukaryotic cells. The catalytic subunit CaPph3 forms a complex with the regulatory subunit CaPsy2, which dephosphorylates activated CaRad53 during adaptation to and recovery from MMS-mediated DNA damage. We show here that the N-terminal Y33A mutation of CaPsy2 blocks the interaction between CaPph3 and CaRad53, the deactivation of CaRad53 and the morphologic switch in recovery from genotoxic stress. In Saccharomyces cerevisiae, the ScPph3-ScPsy2-ScPsy4 complex functions to dephosphorylate γH2A. In this study, we show that CaPsy4 is a functional homolog of ScPsy4 and not involved in the deactivation of CaRad53 or CaHta, the ortholog of H2A. However, deletion of CaPSY4 causes C. albicans cells a sensitivity to genotoxic reagents and a defect in DNA damage-induced filamentation. CaPsy4 interacts with both CaPph3 and CaPsy2, but the function of CaPsy4 is independent of CaPph3 and CaPsy2 in response to genotoxic stress. C. albicans cells lacking CaPPH3, CaPSY2 or CaPSY4, and C. albicans cells carrying the Y33A mutation of CaPSY2, show increased virulence to mice. Therefore, PP4 plays a negative role in regulating the DNA damage-induced filamentation and the virulence in C. albicans.
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Affiliation(s)
- Jinrong Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Yinong Duan
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Yongwei Qin
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Wei Sun
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Zhong Zhuang
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Dandan Zhu
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Linghuo Jiang
- Laboratory for Yeast Molecular and Cell Biology, The Research Center of Fermentation Technology, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255000, China.
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Woolford CA, Lagree K, Aleynikov T, Mitchell AP. Negative control of Candida albicans filamentation-associated gene expression by essential protein kinase gene KIN28. Curr Genet 2017; 63:1073-1079. [PMID: 28501989 DOI: 10.1007/s00294-017-0705-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/25/2017] [Accepted: 05/10/2017] [Indexed: 12/31/2022]
Abstract
The fungus Candida albicans can grow as either yeast or filaments, which include hyphae and pseudohyphae, depending on environmental conditions. Filamentous growth is of particular interest because it is required for biofilm formation and for pathogenesis. Environmentally induced filamentous growth is associated with expression of filamentation-associated genes, and both filamentous growth and associated gene expression depend upon several well-characterized transcription factors. Surprisingly, strains with reduced expression of many essential genes display filamentous growth under non-inducing conditions-those in which the wild type grows as yeast. We found recently that diminished expression of several essential protein kinase genes leads to both filamentous cell morphology and filamentation-associated gene expression under non-inducing conditions. Reduced expression of the essential protein kinase gene CAK1 promoted filamentation-associated gene expression and biofilm formation in strains that lacked key transcriptional activators of these processes, thus indicating that CAK1 expression is critical for both environmental and genetic control of filamentation. In this study, we extend our genetic interaction analysis to a second essential protein kinase gene, KIN28. Reduced expression of KIN28 also permits filamentation-associated gene expression, though not biofilm formation, in the absence of several key transcriptional activators. Our results argue that impairment of several essential cellular processes can alter the regulatory requirements for filamentation-associated gene expression. Our results also indicate that levels of filamentation-associated gene expression are not fully predictive of biofilm formation ability.
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Affiliation(s)
- C A Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - K Lagree
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - T Aleynikov
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - A P Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA.
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Staurosporine Induces Filamentation in the Human Fungal Pathogen Candida albicans via Signaling through Cyr1 and Protein Kinase A. mSphere 2017; 2:mSphere00056-17. [PMID: 28261668 PMCID: PMC5332603 DOI: 10.1128/msphere.00056-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 02/09/2017] [Indexed: 01/10/2023] Open
Abstract
The impact of fungal pathogens on human health is devastating. One of the most pervasive fungal pathogens is Candida albicans, which kills ~40% of people suffering from bloodstream infections. Treatment of these infections is extremely difficult, as fungi are closely related to humans, and there are limited drugs that kill the fungus without host toxicity. The capacity of C. albicans to transition between yeast and filamentous forms is a key virulence trait. Thus, understanding the genetic pathways that regulate morphogenesis could provide novel therapeutic targets to treat C. albicans infections. Here, we establish the small molecule staurosporine as an inducer of filamentous growth. We unveil distinct regulatory circuitry required for staurosporine-induced filamentation that appears to be unique to this filament-inducing cue. Thus, this work highlights the fact that small molecules, such as staurosporine, can improve our understanding of the pathways required for key virulence programs, which may lead to the development of novel therapeutics. Protein kinases are key regulators of signal transduction pathways that participate in diverse cellular processes. In fungal pathogens, kinases regulate signaling pathways that govern drug resistance, stress adaptation, and pathogenesis. The impact of kinases on the fungal regulatory circuitry has recently garnered considerable attention in the opportunistic fungal pathogen Candida albicans, which is a leading cause of human morbidity and mortality. Complex regulatory circuitry governs the C. albicans morphogenetic transition between yeast and filamentous growth, which is a key virulence trait. Here, we report that staurosporine, a promiscuous kinase inhibitor that abrogates fungal drug resistance, also influences C. albicans morphogenesis by inducing filamentation in the absence of any other inducing cue. We further establish that staurosporine exerts its effect via the adenylyl cyclase Cyr1 and the cyclic AMP (cAMP)-dependent protein kinase A (PKA). Strikingly, filamentation induced by staurosporine does not require the known upstream regulators of Cyr1, Ras1 or Pkc1, or effectors downstream of PKA, including Efg1. We further demonstrate that Cyr1 is capable of activating PKA to enable filamentation in response to staurosporine through a mechanism that does not require degradation of the transcriptional repressor Nrg1. We establish that staurosporine-induced filamentation is accompanied by a defect in septin ring formation, implicating cell cycle kinases as potential staurosporine targets underpinning this cellular response. Thus, we establish staurosporine as a chemical probe to elucidate the architecture of cellular signaling governing fungal morphogenesis and highlight the existence of novel circuitry through which the Cyr1 and PKA govern a key virulence trait. IMPORTANCE The impact of fungal pathogens on human health is devastating. One of the most pervasive fungal pathogens is Candida albicans, which kills ~40% of people suffering from bloodstream infections. Treatment of these infections is extremely difficult, as fungi are closely related to humans, and there are limited drugs that kill the fungus without host toxicity. The capacity of C. albicans to transition between yeast and filamentous forms is a key virulence trait. Thus, understanding the genetic pathways that regulate morphogenesis could provide novel therapeutic targets to treat C. albicans infections. Here, we establish the small molecule staurosporine as an inducer of filamentous growth. We unveil distinct regulatory circuitry required for staurosporine-induced filamentation that appears to be unique to this filament-inducing cue. Thus, this work highlights the fact that small molecules, such as staurosporine, can improve our understanding of the pathways required for key virulence programs, which may lead to the development of novel therapeutics.
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Dong Y, Zhang D, Yu Q, Zhao Q, Xiao C, Zhang K, Jia C, Chen S, Zhang B, Zhang B, Li M. Loss of Ssq1 leads to mitochondrial dysfunction, activation of autophagy and cell cycle arrest due to iron overload triggered by mitochondrial iron-sulfur cluster assembly defects in Candida albicans. Int J Biochem Cell Biol 2017; 85:44-55. [PMID: 28163187 DOI: 10.1016/j.biocel.2017.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 12/30/2016] [Accepted: 01/29/2017] [Indexed: 01/10/2023]
Abstract
Iron-sulfur clusters perform essential functions in enzymatic catalysis and homeostatic regulation. Here we for the first time identified Ssq1 as an essential component for iron-sulfur cluster assembly in Candida albicans. Ssq1 played an important role in cell growth. Shutting off SSQ1 led to accumulation of intracellular iron, especially in mitochondria, and disorder of intracellular iron regulation. In tetO-SSQ1, iron overloading triggered the oxidative damage of mitochondrial function. Surprisingly, disruption of SSQ1 activated autophagic pathway. The mitochondrial dysfunction was further aggravated when CCZ1 (which is essential for autophagy) and SSQ1 was simultaneously deleted, suggesting that autophagy played a critical role in maintenance of mitochondrial function in tetO-SSQ1. In addition, double deletion of SSQ1 and CCZ1 further elevated cellular iron levels in comparison with tetO-SSQ1, indicating that autophagy participated in maintenance of iron homeostasis. Furthermore, we found that loss of SSQ1 led to increasing protein expression of Rnr1 and redistribution of Rnr2 from the nucleus to cytoplasm, and further resulted in cell cycle arrest. The results implied that cell cycle arrest was caused by activating the checkpoint pathway because of impairing the iron-sulfur cluster assembly in tetO-SSQ1. Shutting off SSQ1 led to a significant defect in filamentous development. Interestingly, the tetO-SSQ1ccz1Δ/Δ growth was inhibited on hyphae-inducing solid media. Both tetO-SSQ1 and tetO-SSQ1ccz1Δ/Δ exhibited extremely attenuated virulence, indicating that Ssq1 might provide a promising target for antifungal drugs development. In summary, our findings provide new insights into the understanding of iron-sulfur cluster assembly-related gene in C. albicans.
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Affiliation(s)
- Yijie Dong
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China; The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, PR China
| | - Dan Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Qiang Zhao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Chenpeng Xiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Kai Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Chang Jia
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Sijia Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Biao Zhang
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China.
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Woolford CA, Lagree K, Xu W, Aleynikov T, Adhikari H, Sanchez H, Cullen PJ, Lanni F, Andes DR, Mitchell AP. Bypass of Candida albicans Filamentation/Biofilm Regulators through Diminished Expression of Protein Kinase Cak1. PLoS Genet 2016; 12:e1006487. [PMID: 27935965 PMCID: PMC5147786 DOI: 10.1371/journal.pgen.1006487] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/15/2016] [Indexed: 12/17/2022] Open
Abstract
Biofilm formation on implanted medical devices is a major source of lethal invasive infection by Candida albicans. Filamentous growth of this fungus is tied to biofilm formation because many filamentation-associated genes are required for surface adherence. Cell cycle or cell growth defects can induce filamentation, but we have limited information about the coupling between filamentation and filamentation-associated gene expression after cell cycle/cell growth inhibition. Here we identified the CDK activating protein kinase Cak1 as a determinant of filamentation and filamentation-associated gene expression through a screen of mutations that diminish expression of protein kinase-related genes implicated in cell cycle/cell growth control. A cak1diminished expression (DX) strain displays filamentous growth and expresses filamentation-associated genes in the absence of typical inducing signals. In a wild-type background, expression of filamentation-associated genes depends upon the transcription factors Bcr1, Brg1, Efg1, Tec1, and Ume6. In the cak1 DX background, the dependence of filamentation-associated gene expression on each transcription factor is substantially relieved. The unexpected bypass of filamentation-associated gene expression activators has the functional consequence of enabling biofilm formation in the absence of Bcr1, Brg1, Tec1, Ume6, or in the absence of both Brg1 and Ume6. It also enables filamentous cell morphogenesis, though not biofilm formation, in the absence of Efg1. Because these transcription factors are known to have shared target genes, we suggest that cell cycle/cell growth limitation leads to activation of several transcription factors, thus relieving dependence on any one. The ability of the pathogen Candida albicans to grow on surfaces as biofilms is a determinant of infection ability, because biofilms on implanted medical devices seed infections. Biofilm formation by this organism requires growth in the form of filamentous cells and the expression of filamentation-associated genes. Inhibition of cell proliferation can induce filamentous cell formation, as we find here for strains that express greatly reduced levels of the cell cycle regulator Cak1. Surprisingly, biofilm formation occurs independently of many central biofilm regulatory genes when Cak1 levels are reduced. This response to proliferation inhibition may reflect the activation of numerous biofilm regulators, thus relieving the dependence on any one regulator. The stimulation of biofilm formation by proliferation inhibition, a property of many bacterial pathogens as well, may contribute to the limited effectiveness of antimicrobials against biofilms.
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Affiliation(s)
- Carol A. Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Katherine Lagree
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Wenjie Xu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Tatyana Aleynikov
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Hema Adhikari
- Department of Biological Sciences at the University at Buffalo, Buffalo, New York, United States of America
| | - Hiram Sanchez
- Departments of Medicine and Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Paul J. Cullen
- Department of Biological Sciences at the University at Buffalo, Buffalo, New York, United States of America
| | - Frederick Lanni
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - David R. Andes
- Departments of Medicine and Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Aaron P. Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Sds22 participates in Glc7 mediated Rad53 dephosphorylation in MMS-induced DNA damage in Candida albicans. Fungal Genet Biol 2016; 93:50-61. [DOI: 10.1016/j.fgb.2016.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/03/2016] [Accepted: 06/17/2016] [Indexed: 01/21/2023]
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Feng J, Duan Y, Sun W, Qin Y, Zhuang Z, Zhu D, Sun X, Jiang L. CaTip41 regulates protein phosphatase 2A activity, CaRad53 deactivation and the recovery of DNA damage-induced filamentation to yeast form in Candida albicans. FEMS Yeast Res 2016; 16:fow009. [PMID: 26851402 DOI: 10.1093/femsyr/fow009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2016] [Indexed: 02/07/2023] Open
Abstract
Phosphorylation and dephosphorylation of the checkpoint kinase CaRad53 is crucial for fungal cells in response to genotoxic stresses. The protein phosphatase 2A (PP2A) CaPph3/CaPsy2 phosphatase complex is involved in CaRad53 dephosphorylation in Candida albicans. In view of the role of ScTip41/ScTap42 in regulating PP2A phosphatases in Saccharomyces cerevisiae, we have explored the function of CaTip41 in C. albicans. Here, we show that CaTIP41 is a functional ortholog of ScTIP41 in the sensitivity of S. cerevisiae cells to rapamycin. Deletion of CaTIP41 causes C. albicans cells to be sensitive to DNA damaging agents, methylmethane sulfonate (MMS) and cisplatin, and resistant to both rapamycin and caffeine. Accordingly, expression of CaTip41 increases in response to MMS and cisplatin. In addition, C. albicans cells lacking CaTIP41 show a delay in the recovery from MMS-induced filamentation to yeast form, decreased PP2A activity and a defect in deactivation of CaRad53 during recovery from DNA damage. Through yeast two-hybrid assay we show that CaTip41 interacts with either CaPph3, CaPsy2 or CaTap42. Therefore, CaTip41 plays regulatory roles in both the CaRad53 deactivation during recovery from DNA damage and the target of rapamycin signaling pathway.
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Affiliation(s)
- Jinrong Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Yinong Duan
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Wei Sun
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Yongwei Qin
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Zhong Zhuang
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Dandan Zhu
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Xiaolei Sun
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, China
| | - Linghuo Jiang
- The National Engineering Laboratory for Cereal Fermentation Technology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
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Candida albicans Kinesin Kar3 Depends on a Cik1-Like Regulatory Partner Protein for Its Roles in Mating, Cell Morphogenesis, and Bipolar Spindle Formation. EUKARYOTIC CELL 2015; 14:755-74. [PMID: 26024903 DOI: 10.1128/ec.00015-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 05/26/2015] [Indexed: 02/05/2023]
Abstract
Candida albicans is a major fungal pathogen whose virulence is associated with its ability to transition from a budding yeast form to invasive hyphal filaments. The kinesin-14 family member CaKar3 is required for transition between these morphological states, as well as for mitotic progression and karyogamy. While kinesin-14 proteins are ubiquitous, CaKar3 homologs in hemiascomycete fungi are unique because they form heterodimers with noncatalytic kinesin-like proteins. Thus, CaKar3-based motors may represent a novel antifungal drug target. We have identified and examined the roles of a kinesin-like regulator of CaKar3. We show that orf19.306 (dubbed CaCIK1) encodes a protein that forms a heterodimer with CaKar3, localizes CaKar3 to spindle pole bodies, and can bind microtubules and influence CaKar3 mechanochemistry despite lacking an ATPase activity of its own. Similar to CaKar3 depletion, loss of CaCik1 results in cell cycle arrest, filamentation defects, and an inability to undergo karyogamy. Furthermore, an examination of the spindle structure in cells lacking either of these proteins shows that a large proportion have a monopolar spindle or two dissociated half-spindles, a phenotype unique to the C. albicans kinesin-14 homolog. These findings provide new insights into mitotic spindle structure and kinesin motor function in C. albicans and identify a potentially vulnerable target for antifungal drug development.
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Oxidative stress responses in the human fungal pathogen, Candida albicans. Biomolecules 2015; 5:142-65. [PMID: 25723552 PMCID: PMC4384116 DOI: 10.3390/biom5010142] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 02/11/2015] [Accepted: 02/12/2015] [Indexed: 02/07/2023] Open
Abstract
Candida albicans is a major fungal pathogen of humans, causing approximately 400,000 life-threatening systemic infections world-wide each year in severely immunocompromised patients. An important fungicidal mechanism employed by innate immune cells involves the generation of toxic reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. Consequently, there is much interest in the strategies employed by C. albicans to evade the oxidative killing by macrophages and neutrophils. Our understanding of how C. albicans senses and responds to ROS has significantly increased in recent years. Key findings include the observations that hydrogen peroxide triggers the filamentation of this polymorphic fungus and that a superoxide dismutase enzyme with a novel mode of action is expressed at the cell surface of C. albicans. Furthermore, recent studies have indicated that combinations of the chemical stresses generated by phagocytes can actively prevent C. albicans oxidative stress responses through a mechanism termed the stress pathway interference. In this review, we present an up-date of our current understanding of the role and regulation of oxidative stress responses in this important human fungal pathogen.
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Pointer BR, Boyer MP, Schmidt M. Boric acid destabilizes the hyphal cytoskeleton and inhibits invasive growth ofCandida albicans. Yeast 2015; 32:389-98. [DOI: 10.1002/yea.3066] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 12/12/2014] [Accepted: 01/14/2015] [Indexed: 11/05/2022] Open
Affiliation(s)
| | - Michael P. Boyer
- Department of Biochemistry and Nutrition; Des Moines University; IA USA
| | - Martin Schmidt
- Department of Biochemistry and Nutrition; Des Moines University; IA USA
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Greig JA, Sudbery IM, Richardson JP, Naglik JR, Wang Y, Sudbery PE. Cell cycle-independent phospho-regulation of Fkh2 during hyphal growth regulates Candida albicans pathogenesis. PLoS Pathog 2015; 11:e1004630. [PMID: 25617770 PMCID: PMC4305328 DOI: 10.1371/journal.ppat.1004630] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 12/16/2014] [Indexed: 11/21/2022] Open
Abstract
The opportunistic human fungal pathogen, Candida albicans, undergoes morphological and transcriptional adaptation in the switch from commensalism to pathogenicity. Although previous gene-knockout studies have identified many factors involved in this transformation, it remains unclear how these factors are regulated to coordinate the switch. Investigating morphogenetic control by post-translational phosphorylation has generated important regulatory insights into this process, especially focusing on coordinated control by the cyclin-dependent kinase Cdc28. Here we have identified the Fkh2 transcription factor as a regulatory target of both Cdc28 and the cell wall biosynthesis kinase Cbk1, in a role distinct from its conserved function in cell cycle progression. In stationary phase yeast cells 2D gel electrophoresis shows that there is a diverse pool of Fkh2 phospho-isoforms. For a short window on hyphal induction, far before START in the cell cycle, the phosphorylation profile is transformed before reverting to the yeast profile. This transformation does not occur when stationary phase cells are reinoculated into fresh medium supporting yeast growth. Mass spectrometry and mutational analyses identified residues phosphorylated by Cdc28 and Cbk1. Substitution of these residues with non-phosphorylatable alanine altered the yeast phosphorylation profile and abrogated the characteristic transformation to the hyphal profile. Transcript profiling of the phosphorylation site mutant revealed that the hyphal phosphorylation profile is required for the expression of genes involved in pathogenesis, host interaction and biofilm formation. We confirmed that these changes in gene expression resulted in corresponding defects in pathogenic processes. Furthermore, we identified that Fkh2 interacts with the chromatin modifier Pob3 in a phosphorylation-dependent manner, thereby providing a possible mechanism by which the phosphorylation of Fkh2 regulates its specificity. Thus, we have discovered a novel cell cycle-independent phospho-regulatory event that subverts a key component of the cell cycle machinery to a role in the switch from commensalism to pathogenicity. The fungus Candida albicans is a commensal in the human microbiota, responsible for superficial infections such as oral and vaginal thrush. However, it can become highly virulent, causing life-threatening systemic candidemia in severely immunocompromised patients, including those taking immunosuppressive drugs for transplantation, sufferers of AIDS and neutropenia, and individuals undergoing chemotherapy or at extremes of age. With a rapidly increasing ageing population worldwide, C. albicans and other fungal pathogens will become more prevalent, demanding a greater understanding of their pathogenesis for the development of effective therapeutics. Fungal pathogenicity requires a coordinated change in the pattern of gene expression orchestrated by a set of transcription factors. Here we have discovered that a transcription factor, Fkh2, is modified by phosphorylation under the control of the kinases Cdc28 and Cbk1 in response to conditions that activate virulence factor expression. Fkh2 is involved in a wide variety of cellular processes including cell proliferation, but this phosphorylation endows it with a specialized function in promoting the expression of genes required for tissue invasion, biofilm formation, and pathogenesis in the host. This study highlights the role of protein phosphorylation in regulating pathogenesis and furthers our understanding of the pathogenic switch in this important opportunistic fungal pathogen.
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Affiliation(s)
- Jamie A. Greig
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, United Kingdom
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
| | - Ian M. Sudbery
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jonathan P. Richardson
- Mucosal and Salivary Biology Division, King’s College London Dental Institute, King’s College London, London, United Kingdom
| | - Julian R. Naglik
- Mucosal and Salivary Biology Division, King’s College London Dental Institute, King’s College London, London, United Kingdom
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
- Department of Biochemistry, Yong Loo Ling School of Medicine, National University of Singapore, Singapore
- * E-mail: (PES); (YW)
| | - Peter E. Sudbery
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, United Kingdom
- * E-mail: (PES); (YW)
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Ascorbic acid inhibition of Candida albicans Hsp90-mediated morphogenesis occurs via the transcriptional regulator Upc2. EUKARYOTIC CELL 2014; 13:1278-89. [PMID: 25084864 DOI: 10.1128/ec.00096-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Morphogenetic transitions of the opportunistic fungal pathogen Candida albicans are influenced by temperature changes, with induction of filamentation upon a shift from 30 to 37°C. Hsp90 was identified as a major repressor of an elongated cell morphology at low temperatures, as treatment with specific inhibitors of Hsp90 results in elongated growth forms at 30°C. Elongated growth resulting from a compromised Hsp90 is considered neither hyphal nor pseudohyphal growth. It has been reported that ascorbic acid (vitamin C) interferes with the yeast-to-hypha transition in C. albicans. In the present study, we show that ascorbic acid also antagonizes the morphogenetic change caused by hampered Hsp90 function. Further analysis revealed that Upc2, a transcriptional regulator of genes involved in ergosterol biosynthesis, and Erg11, the target of azole antifungals, whose expression is in turn regulated by Upc2, are required for this antagonism. Ergosterol levels correlate with elongated growth and are reduced in cells treated with the Hsp90 inhibitor geldanamycin (GdA) and restored by cotreatment with ascorbic acid. In addition, we show that Upc2 appears to be required for ascorbic acid-mediated inhibition of the antifungal activity of fluconazole. These results identify Upc2 as a major regulator of ascorbic acid-induced effects in C. albicans and suggest an association between ergosterol content and elongated growth upon Hsp90 compromise.
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Kamthan M, Nalla VK, Ruhela D, Kamthan A, Maiti P, Datta A. Characterization of a putative spindle assembly checkpoint kinase Mps1, suggests its involvement in cell division, morphogenesis and oxidative stress tolerance in Candida albicans. PLoS One 2014; 9:e101517. [PMID: 25025778 PMCID: PMC4098995 DOI: 10.1371/journal.pone.0101517] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 06/09/2014] [Indexed: 01/14/2023] Open
Abstract
In Saccharomyces cerevisiae MPS1 is one of the major protein kinase that governs the spindle checkpoint pathway. The S. cerevisiae structural homolog of opportunistic pathogen Candida albicans CaMPS1, is indispensable for the cell viability. The essentiality of Mps1 was confirmed by Homozygote Trisome test. To determine its biological function in this pathogen conditional mutant was generated through regulatable MET3 promoter. Examination of heterozygous and conditional (+Met/Cys) mps1 mutants revealed a mitosis specific arrest phenotype, where mutants showed large buds with undivided nuclei. Flowcytometry analysis revealed abnormal ploidy levels in mps1mutant. In presence of anti-microtubule drug Nocodazole, mps1 mutant showed a dramatic loss of viability suggesting a role of Mps1 in Spindle Assembly Checkpoint (SAC) activation. These mutants were also defective in microtubule organization. Moreover, heterozygous mutant showed defective in-vitro yeast to hyphae morphological transition. Growth defect in heterozygous mutant suggest haploinsufficiency of this gene. qRT PCR analysis showed around 3 fold upregulation of MPS1 in presence of serum. This expression of MPS1 is dependent on Efg1and is independent of other hyphal regulators like Ras1 and Tpk2. Furthermore, mps1 mutants were also sensitive to oxidative stress. Heterozygous mps1 mutant did not undergo morphological transition and showed 5-Fold reduction in colony forming units in response to macrophage. Thus, the vital checkpoint kinase, Mps1 besides cell division also has a role in morphogenesis and oxidative stress tolerance, in this pathogenic fungus.
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Affiliation(s)
- Mohan Kamthan
- National Institute of Plant Genome Research, New Delhi, India
| | - Vijaya Kumar Nalla
- Department of Microbiology, Bhaskaracharya college, University of Delhi, New Delhi, India
| | - Deepa Ruhela
- National Institute of Plant Genome Research, New Delhi, India
| | - Ayushi Kamthan
- National Institute of Plant Genome Research, New Delhi, India
| | - Protiti Maiti
- National Institute of Plant Genome Research, New Delhi, India
| | - Asis Datta
- National Institute of Plant Genome Research, New Delhi, India
- * E-mail:
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46
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Role of Candida albicans Tem1 in mitotic exit and cytokinesis. Fungal Genet Biol 2014; 69:84-95. [PMID: 24973462 DOI: 10.1016/j.fgb.2014.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 06/12/2014] [Accepted: 06/17/2014] [Indexed: 11/20/2022]
Abstract
Candida albicans demonstrates three main growth morphologies: yeast, pseudohyphal and true hyphal forms. Cell separation is distinct in these morphological forms and the process of separation is closely linked to the completion of mitosis and cytokinesis. In Saccharomyces cerevisiae the small GTPase Tem1 is known to initiate the mitotic exit network, a signalling pathway involved in signalling the end of mitosis and initiating cytokinesis and cell separation. Here we have characterised the role of Tem1 in C. albicans, and demonstrate that it is essential for mitotic exit and cytokinesis, and that this essential function is signalled through the kinase Cdc15. Cells depleted of Tem1 displayed highly polarised growth but ultimately failed to both complete cytokinesis and re-enter the cell cycle following nuclear division. Consistent with its role in activating the mitotic exit network Tem1 localises to spindle pole bodies in a cell cycle-dependent manner. Ultimately, the mitotic exit network in C. albicans appears to co-ordinate the sequential processes of mitotic exit, cytokinesis and cell separation.
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47
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O'Meara TR, Cowen LE. Hsp90-dependent regulatory circuitry controlling temperature-dependent fungal development and virulence. Cell Microbiol 2014; 16:473-81. [PMID: 24438186 DOI: 10.1111/cmi.12266] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 11/28/2022]
Abstract
The pathogenic fungi Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans are an increasing cause of human mortality, especially in immunocompromised populations. During colonization and adaptation to various host environments, these fungi undergo morphogenetic alterations that allow for survival within the host. One key environmental cue driving morphological changes is external temperature. The Hsp90 chaperone protein provides one mechanism to link temperature with the signalling cascades that regulate morphogenesis, fungal development and virulence. Candida albicans is a model system for understanding the connections between morphogenesis and Hsp90. Due to the high degree of conservation in Hsp90, many of the connections in C. albicans may be extrapolated to other fungal pathogens or parasites. Examining the role of Hsp90 during development and morphogenesis in these three major fungal pathogens may provide insight into key aspects of adaptation to the host, leading to additional avenues for therapy.
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Affiliation(s)
- Teresa R O'Meara
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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48
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Loll-Krippleber R, d'Enfert C, Feri A, Diogo D, Perin A, Marcet-Houben M, Bougnoux ME, Legrand M. A study of the DNA damage checkpoint inCandida albicans: uncoupling of the functions of Rad53 in DNA repair, cell cycle regulation and genotoxic stress-induced polarized growth. Mol Microbiol 2013; 91:452-71. [DOI: 10.1111/mmi.12471] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2013] [Indexed: 01/25/2023]
Affiliation(s)
- Raphaël Loll-Krippleber
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
- Univ. Paris Diderot; Sorbonne Paris Cité, Cellule Pasteur; rue du Docteur Roux F-75015 Paris France
| | - Christophe d'Enfert
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
| | - Adeline Feri
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
- Univ. Paris Diderot; Magistère Européen de Génétique, Sorbonne Paris Cité, Cellule Pasteur; rue du Docteur Roux F-75015 Paris France
| | - Dorothée Diogo
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
- Univ. Paris Diderot; Sorbonne Paris Cité, Cellule Pasteur; rue du Docteur Roux F-75015 Paris France
| | - Aurélie Perin
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
| | - Marina Marcet-Houben
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
| | - Marie-Elisabeth Bougnoux
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
| | - Mélanie Legrand
- Institut Pasteur; Unité Biologie et Pathogénicité Fongiques; Département Génomes et Génétique; 25, rue du Docteur Roux F-75015 Paris France
- INRA USC2019; 25, rue du Docteur Roux F-75015 Paris France
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49
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Deciphering the transcriptional-regulatory network of flocculation in Schizosaccharomyces pombe. PLoS Genet 2012; 8:e1003104. [PMID: 23236291 PMCID: PMC3516552 DOI: 10.1371/journal.pgen.1003104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 10/03/2012] [Indexed: 01/07/2023] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, the transcriptional-regulatory network that governs flocculation remains poorly understood. Here, we systematically screened an array of transcription factor deletion and overexpression strains for flocculation and performed microarray expression profiling and ChIP-chip analysis to identify the flocculin target genes. We identified five transcription factors that displayed novel roles in the activation or inhibition of flocculation (Rfl1, Adn2, Adn3, Sre2, and Yox1), in addition to the previously-known Mbx2, Cbf11, and Cbf12 regulators. Overexpression of mbx2(+) and deletion of rfl1(+) resulted in strong flocculation and transcriptional upregulation of gsf2(+)/pfl1(+) and several other putative flocculin genes (pfl2(+)-pfl9(+)). Overexpression of the pfl(+) genes singly was sufficient to trigger flocculation, and enhanced flocculation was observed in several combinations of double pfl(+) overexpression. Among the pfl1(+) genes, only loss of gsf2(+) abrogated the flocculent phenotype of all the transcription factor mutants and prevented flocculation when cells were grown in inducing medium containing glycerol and ethanol as the carbon source, thereby indicating that Gsf2 is the dominant flocculin. In contrast, the mild flocculation of adn2(+) or adn3(+) overexpression was likely mediated by the transcriptional activation of cell wall-remodeling genes including gas2(+), psu1(+), and SPAC4H3.03c. We also discovered that Mbx2 and Cbf12 displayed transcriptional autoregulation, and Rfl1 repressed gsf2(+) expression in an inhibitory feed-forward loop involving mbx2(+). These results reveal that flocculation in S. pombe is regulated by a complex network of multiple transcription factors and target genes encoding flocculins and cell wall-remodeling enzymes. Moreover, comparisons between the flocculation transcriptional-regulatory networks of Saccharomyces cerevisiae and S. pombe indicate substantial rewiring of transcription factors and cis-regulatory sequences.
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Sellam A, Tebbji F, Whiteway M, Nantel A. A novel role for the transcription factor Cwt1p as a negative regulator of nitrosative stress in Candida albicans. PLoS One 2012; 7:e43956. [PMID: 22952822 PMCID: PMC3430608 DOI: 10.1371/journal.pone.0043956] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 07/27/2012] [Indexed: 11/21/2022] Open
Abstract
The ability of Candida albicans to survive in the presence of nitrosative stress during the initial contact with the host immune system is crucial for its ability to colonize mammalian hosts. Thus, this fungus must activate robust mechanisms to neutralize and repair nitrosative-induced damage. Until now, very little was known regarding the regulatory circuits associated with reactive nitrogen species detoxification in fungi. To gain insight into the transcriptional regulatory networks controlling nitrosative stress response (NRS) in C. albicans a compilation of transcriptional regulator-defective mutants were screened. This led to the identification of Cwt1p as a negative regulator of NSR. By combining genome-wide location and expression analyses, we have characterized the Cwt1p regulon and demonstrated that Cwt1p is directly required for proper repression of the flavohemoglobin Yhb1p, a key NO-detoxification enzyme. Furthermore, Cwt1p operates both by activating and repressing genes of specific functions solicited upon NSR. Additionally, we used Gene Set Enrichment Analysis to reinvestigate the C. albicans NSR-transcriptome and demonstrate a significant similarity with the transcriptional profiles of C. albicans interacting with phagocytic host-cells. In summary, we have characterized a novel negative regulator of NSR and bring new insights into the transcriptional regulatory network governing fungal NSR.
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Affiliation(s)
- Adnane Sellam
- Institute for Research in Immunology and Cancer (IRIC), University of Montreal, Montréal, QC, Canada
- * E-mail: (AS); (AN)
| | - Faiza Tebbji
- Biotechnology Research Institute, National Research Council of Canada, Montréal, QC, Canada
- Department of Biology, McGill University, Montréal, QC, Canada
| | - Malcolm Whiteway
- Biotechnology Research Institute, National Research Council of Canada, Montréal, QC, Canada
- Department of Biology, McGill University, Montréal, QC, Canada
| | - André Nantel
- Biotechnology Research Institute, National Research Council of Canada, Montréal, QC, Canada
- Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
- * E-mail: (AS); (AN)
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