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Zeng G, Xu X, Kok YJ, Deng FS, Ling Chow EW, Gao J, Bi X, Wang Y. Cytochrome c regulates hyphal morphogenesis by interfering with cAMP-PKA signaling in Candida albicans. Cell Rep 2023; 42:113473. [PMID: 37980562 DOI: 10.1016/j.celrep.2023.113473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/17/2023] [Accepted: 11/06/2023] [Indexed: 11/21/2023] Open
Abstract
In the human fungal pathogen Candida albicans, invasive hyphal growth is a well-recognized virulence trait. We employed transposon-mediated genome-wide mutagenesis, revealing that inactivating CTM1 blocks hyphal growth. CTM1 encodes a lysine (K) methyltransferase, which trimethylates cytochrome c (Cyc1) at K79. Mutants lacking CTM1 or expressing cyc1K79A grow as yeast under hyphae-inducing conditions, indicating that unmethylated Cyc1 suppresses hyphal growth. Transcriptomic analyses detected increased levels of the hyphal repressor NRG1 and decreased levels of hyphae-specific genes in ctm1Δ/Δ and cyc1K79A mutants, suggesting cyclic AMP (cAMP)-protein kinase A (PKA) signaling suppression. Co-immunoprecipitation and in vitro kinase assays demonstrated that unmethylated Cyc1 inhibits PKA kinase activity. Surprisingly, hyphae-defective ctm1Δ/Δ and cyc1K79A mutants remain virulent in mice due to accelerated proliferation. Our results unveil a critical role for cytochrome c in maintaining the virulence of C. albicans by orchestrating proliferation, growth mode, and metabolism. Importantly, this study identifies a biological function for lysine methylation on cytochrome c.
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Affiliation(s)
- Guisheng Zeng
- A(∗)STAR Infectious Diseases Labs (A(∗)STAR ID Labs), Agency for Science, Technology and Research (A(∗)STAR), 8A Biomedical Grove, #05-13 Immunos, Singapore 138648, Singapore.
| | - Xiaoli Xu
- A(∗)STAR Infectious Diseases Labs (A(∗)STAR ID Labs), Agency for Science, Technology and Research (A(∗)STAR), 8A Biomedical Grove, #05-13 Immunos, Singapore 138648, Singapore
| | - Yee Jiun Kok
- Bioprocessing Technology Institute, 20 Biopolis Way, #06-01 Centros, Singapore 138668, Singapore
| | - Fu-Sheng Deng
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Eve Wai Ling Chow
- A(∗)STAR Infectious Diseases Labs (A(∗)STAR ID Labs), Agency for Science, Technology and Research (A(∗)STAR), 8A Biomedical Grove, #05-13 Immunos, Singapore 138648, Singapore
| | - Jiaxin Gao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuezhi Bi
- Bioprocessing Technology Institute, 20 Biopolis Way, #06-01 Centros, Singapore 138668, Singapore; Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore
| | - Yue Wang
- A(∗)STAR Infectious Diseases Labs (A(∗)STAR ID Labs), Agency for Science, Technology and Research (A(∗)STAR), 8A Biomedical Grove, #05-13 Immunos, Singapore 138648, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
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2
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Zeng G, Neo SP, Pang LM, Gao J, Chong SC, Gunaratne J, Wang Y. Comprehensive Interactome Analysis for the Sole Adenylyl Cyclase Cyr1 of Candida albicans. Microbiol Spectr 2022; 10:e0393422. [PMID: 36314909 PMCID: PMC9769623 DOI: 10.1128/spectrum.03934-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022] Open
Abstract
Cyr1, the sole adenylyl cyclase of the fungal pathogen Candida albicans, is a central component of the cAMP/protein kinase A signaling pathway that controls the yeast-to-hypha transition. Cyr1 is a multivalent sensor and integrator of various external and internal signals. To better understand how these signals are relayed to Cyr1 to regulate its activity, we sought to establish the interactome of Cyr1 by using stable isotope labeling by amino acids in cell culture (SILAC)-based quantitative proteomics to identify the proteins that coimmunoprecipitated with Cyr1. The method identified 36 proteins as candidates for authentic Cyr1-interacting partners, together with two known Cyr1-binding proteins, Cap1 and Act1. Fourteen identified proteins belonged to three functional groups, including actin regulation, cell wall components, and mitochondrial activities, that are known to play important roles in cell morphogenesis. To validate the proteomics data, we used biochemical and genetic methods to characterize two cell wall-related proteins, Mp65 and Sln1. First, coimmunoprecipitation confirmed their physical association with Cyr1. Second, deleting either MP65 or SLN1 resulted in severe defects in filamentation on serum plates. This study establishes the first Cyr1 interactome and uncovers a potential role for cell wall proteins in directly regulating Cyr1 activity to determine growth forms in C. albicans. IMPORTANCE A critical virulence trait of the human fungal pathogen Candida albicans is its ability to undergo the yeast-to-hypha transition in response to diverse environmental and cellular stimuli. Previous studies suggested that the sole adenylyl cyclase of C. albicans, Cyr1, is a multivalent signal sensor and integrator synthesizing cAMP to activate the downstream hypha-promoting events through the cAMP/protein kinase A pathway. To fully understand how Cyr1 senses and processes multiple stimuli to generate appropriate signal outputs, it was necessary to identify and characterize Cyr1-interacting partners. This study employed SILAC-based quantitative proteomic approaches and identified 36 Cyr1-associated proteins, many having functions associated with hyphal morphogenesis. Coimmunoprecipitation verified two cell surface proteins, Mp65 and Sln1. Furthermore, genetic and phenotypic analyses demonstrated the cAMP-dependent roles of these two proteins in determining hyphal growth. Our study establishes the first Cyr1 interactome and uncovers new Cyr1 regulators that mediate cell surface signals to influence the growth mode of C. albicans.
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Affiliation(s)
| | - Suat Peng Neo
- Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Singapore
| | | | | | | | - Jayantha Gunaratne
- Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Singapore
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yue Wang
- Infectious Diseases Labs, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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3
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Genomic Diversity across Candida auris Clinical Isolates Shapes Rapid Development of Antifungal Resistance
In Vitro
and
In Vivo. mBio 2022; 13:e0084222. [PMID: 35862787 PMCID: PMC9426540 DOI: 10.1128/mbio.00842-22] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Antifungal drug resistance and tolerance pose a serious threat to global public health. In the human fungal pathogen, Candida auris, resistance to triazole, polyene, and echinocandin antifungals is rising, resulting in multidrug resistant isolates. Here, we use genome analysis and in vitro evolution of 17 new clinical isolates of C. auris from clades I and IV to determine how quickly resistance mutations arise, the stability of resistance in the absence of drug, and the impact of genetic background on evolutionary trajectories. We evolved each isolate in the absence of drug as well as in low and high concentrations of fluconazole. In just three passages, we observed genomic and phenotypic changes including karyotype alterations, aneuploidy, acquisition of point mutations, and increases in MIC values within the populations. Fluconazole resistance was stable in the absence of drug, indicating little to no fitness cost associated with resistance. Importantly, two isolates substantially increased resistance to ≥256 μg/mL fluconazole. Multiple evolutionary pathways and mutations associated with increased fluconazole resistance occurred simultaneously within the same population. Strikingly, the subtelomeric regions of C. auris were highly dynamic as deletion of multiple genes near the subtelomeres occurred during the three passages in several populations. Finally, we discovered a mutator phenotype in a clinical isolate of C. auris. This isolate had elevated mutation rates compared to other isolates and acquired substantial resistance during evolution in vitro and in vivo supporting that the genetic background of clinical isolates can have a significant effect on evolutionary potential.
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4
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Zeng G, Xu X, Gao J, da Silva Dantas A, Gow NA, Wang Y. Inactivating the mannose-ethanolamine phosphotransferase Gpi7 confers caspofungin resistance in the human fungal pathogen Candida albicans. Cell Surf 2021; 7:100057. [PMID: 34258484 PMCID: PMC8254124 DOI: 10.1016/j.tcsw.2021.100057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 11/24/2022] Open
Abstract
Understanding the molecular mechanisms governing antifungal resistance is crucial for identifying new cellular targets for developing new antifungal therapeutics. In this study, we performed a transposon-mediated genome-wide genetic screen in haploid Candida albicans to identify mutants resistant to caspofungin, the first member of the echinocandin class of antifungal drugs. A mutant exhibiting the highest resistance possessed a transposon insertion that inactivates GPI7, a gene encoding the mannose-ethanolamine phosphotransferase. Deleting GPI7 in diploid C. albicans caused similar caspofungin resistance. gpi7Δ/Δ cells showed significantly elevated cell wall chitin content and enhanced phosphorylation of Mkc1, a core component of the PKC-MAPK cell-wall integrity pathway. Deleting MKC1 suppressed the chitin elevation and caspofungin resistance of gpi7Δ/Δ cells, but overexpressing the dominant inactive form of RHO1, an upstream activator of PKC-MAPK signaling, did not. Transcriptome analysis uncovered 406 differentially expressed genes in gpi7Δ/Δ cells, many related to cell wall construction. Our results suggest that GPI7 deletion impairs cell wall integrity, which triggers the cell-wall salvage mechanism via the PKC-MAPK pathway independently of Rho1, resulting in the compensatory chitin synthesis to confer caspofungin resistance.
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Affiliation(s)
- Guisheng Zeng
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Xiaoli Xu
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Jiaxin Gao
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Alessandra da Silva Dantas
- MRC Centre for Medical Mycology, School of Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Neil A.R. Gow
- MRC Centre for Medical Mycology, School of Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Yue Wang
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
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5
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Li P, Seneviratne CJ, Luan Q, Jin L. Proteomic Analysis of Caspofungin-Induced Responses in Planktonic Cells and Biofilms of Candida albicans. Front Microbiol 2021; 12:639123. [PMID: 33679674 PMCID: PMC7931687 DOI: 10.3389/fmicb.2021.639123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/25/2021] [Indexed: 11/15/2022] Open
Abstract
Candida albicans biofilms display markedly increased antifungal resistance, and the underlying mechanisms remain unclear. This study investigated the signature profiles of C. albicans planktonic cells and biofilms in response to caspofungin (CAS) by mass spectrometry-based shotgun proteomics. We found that C. albicans biofilms were twofold more resistant to CAS with reference to planktonic cells. Notably, 9.6% of C. albicans biofilm cells survived the lethal treatment of CAS (128 μg/ml), confirmed by LIVE/DEAD staining, confocal laser scanning microscopy (CLSM) and scanning electron microscopy analyses. The responses of C. albicans planktonic cells and biofilms to CAS treatment at respective minimum inhibitory concentrations (MICs) were assessed by high-throughput proteomics and bioinformatics approaches. There were 148 and 224 proteins with >twofold difference identified from the planktonic cells and biofilms, respectively. CAS treatment downregulated several cell wall- and oxidative stress-related proteins. Whereas, CAS-induced action was compensated by markedly increased expression of many other proteins involved in cell wall integrity and stress response (e.g., heat shock proteins). Moreover, considerable expression changes were identified in metabolism-associated proteins like glycolysis, tricarboxylic acid (TCA) cycle and ATP biosynthesis. Importantly, various key proteins for cell wall integrity, stress response and metabolic regulation (e.g., PIL1, LSP1, HSP90, ICL1, and MLS1) were exclusively enriched and implicated in C. albicans biofilms. This study demonstrates that C. albicans biofilms undergo highly complicated yet complex regulation of multiple cellular pathways in response to CAS. Signature proteins essential for modulating cell wall integrity, stress response and metabolic activities may account for the antifungal resistance of C. albicans biofilms.
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Affiliation(s)
- Peng Li
- Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China.,Division of Periodontology and Implant Dentistry, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China
| | - Chaminda J Seneviratne
- National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore, Singapore
| | - Qingxian Luan
- Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China
| | - Lijian Jin
- Division of Periodontology and Implant Dentistry, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China
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6
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Truong T, Pang LM, Rajan S, Wong SSW, Fung YME, Samaranayake L, Seneviratne CJ. The Proteome of Community Living Candida albicans Is Differentially Modulated by the Morphologic and Structural Features of the Bacterial Cohabitants. Microorganisms 2020; 8:microorganisms8101541. [PMID: 33036329 PMCID: PMC7601143 DOI: 10.3390/microorganisms8101541] [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: 09/01/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 11/16/2022] Open
Abstract
Candida albicans is a commensal polymorphic and opportunistic fungus, which usually resides as a small community in the oral cavities of a majority of humans. The latter eco-system presents this yeast varied opportunities for mutualistic interactions with other cohabitant oral bacteria, that synergizes its persistence and pathogenicity. Collectively, these communities live within complex plaque biofilms which may adversely affect the oral health and increase the proclivity for oral candidiasis. The proteome of such oral biofilms with myriad interkingdom interactions are largely underexplored. Herein, we employed limma differential expression analysis, and cluster analysis to explore the proteomic interactions of C. albicans biofilms with nine different common oral bacterial species, Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Fusobacterium nucleatum, Enterococcus faecalis, Porphyromonas gingivalis, Streptococcus mutants, Streptococcus sanguinis, Streptococcus mitis, and Streptococcus sobrinus. Interestingly, upon exposure of C. albicans biofilms to the foregoing heat-killed bacteria, the proteomes of the fungus associated with cellular respiration, translation, oxidoreductase activity, and ligase activity were significantly altered. Subsequent differential expression and cluster analysis revealed the subtle, yet significant alterations in the C. albicans proteome, particularly on exposure to bacteria with dissimilar cell morphologies, and Gram staining characteristics.
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Affiliation(s)
- Thuyen Truong
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119085, Singapore;
| | - Li Mei Pang
- National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Singapore 168938, Singapore;
| | - Suhasini Rajan
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, 80336 Munich, Germany;
| | - Sarah Sze Wah Wong
- Molecular Mycology Unit, Institut Pasteur, CNRS, UMR2000, 10098 Paris, France;
| | - Yi Man Eva Fung
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China;
| | - Lakshman Samaranayake
- College of Dental Medicine, University of Sharjah, Sharjah 27272, UAE;
- Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Chaminda Jayampath Seneviratne
- National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Singapore 168938, Singapore;
- Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore
- Correspondence: ; Tel.: +65-65767141
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7
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Srivastava N, Ellepola K, Venkiteswaran N, Chai LYA, Ohshima T, Seneviratne CJ. Lactobacillus Plantarum 108 Inhibits Streptococcus mutans and Candida albicans Mixed-Species Biofilm Formation. Antibiotics (Basel) 2020; 9:antibiotics9080478. [PMID: 32759754 PMCID: PMC7459986 DOI: 10.3390/antibiotics9080478] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/08/2020] [Accepted: 07/21/2020] [Indexed: 12/14/2022] Open
Abstract
Streptococcus mutans is the principal biofilm forming oral pathogen associated with dental caries. Studies have shown that Candida albicans, a commensal oral fungus is capable of forming pathogenic mixed-species biofilms with S. mutans. The treatment of bacterial and fungal infections using conventional antimicrobial agents has become challenging due to the antimicrobial resistance of the biofilm mode of growth. The present study aimed to evaluate the efficacy of secretory components of Lactobacillus plantarum 108, a potentially promising probiotic strain, against S. mutans and C. albicans single and mixed-species biofilms. L. plantarum 108 supernatant inhibited S. mutans and C. albicans single-species biofilms as shown by XTT reduction assay, crystal violet assay, and colony forming units counting. The probiotic supernatant significantly inhibited the S. mutans and C. albicans mixed-species biofilm formation. The pre-formed mixed-species biofilms were also successfully reduced. Confocal microscopy showed poorly developed biofilm architecture in the probiotic supernatant treated biofilms. Moreover, the expression of S. mutans genes associated with glucosyltransferase activity and C. albicans hyphal specific genes (HWP1, ALS1 and ALS3) were down-regulated in the presence of the probiotic supernatant. Altogether, the data demonstrated the capacity of L. plantarum 108 supernatant to inhibit the S. mutans and C. albicans mixed-species biofilms. Herein, we provide a new insight on the potential of probiotic-based strategies to prevent bacterial-fungal mixed-species biofilms associated with dental caries.
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Affiliation(s)
- Neha Srivastava
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 11908, Singapore; (N.S.); or (K.E.); (N.V.)
| | - Kassapa Ellepola
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 11908, Singapore; (N.S.); or (K.E.); (N.V.)
- Center of Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Nityasri Venkiteswaran
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 11908, Singapore; (N.S.); or (K.E.); (N.V.)
| | - Louis Yi Ann Chai
- Division of Infectious Diseases, University Medicine Cluster, National University Health System and Faculty of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore;
| | - Tomoko Ohshima
- Department of Oral Microbiology, School of Dental Medicine, Tsurumi University, Yokohama 230-8501, Japan;
| | - Chaminda Jayampath Seneviratne
- Singapore Oral Microbiomics Initiative, National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, SingHealth Duke NUS Medical School, 5 Second Hospital Avenue, Singapore 168938, Singapore
- Correspondence: ; Tel.: +65-65767141
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8
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Genome-wide piggyBac transposon-based mutagenesis and quantitative insertion-site analysis in haploid Candida species. Nat Protoc 2020; 15:2705-2727. [PMID: 32681154 DOI: 10.1038/s41596-020-0351-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 04/30/2020] [Indexed: 11/08/2022]
Abstract
Invasive fungal infections caused by Candida species are life threatening with high mortality, posing a severe public health threat. New technologies for rapid, genome-wide identification of virulence genes and therapeutic targets are urgently needed. Our recent engineering of a piggyBac (PB) transposon-mediated mutagenesis system in haploid Candida albicans provides a powerful discovery tool, which we anticipate should be adaptable to other haploid Candida species. In this protocol, we use haploid C. albicans as an example to present an improved version of the mutagenesis system and provide a detailed description of the protocol for constructing high-quality mutant libraries. We also describe a method for quantitative PB insertion site sequencing, PBISeq. The PBISeq library preparation procedure exploits tagmentation to quickly and efficiently construct sequencing libraries. Finally, we present a pipeline to analyze PB insertion sites in a de novo assembled genome of our engineered haploid C. albicans strain. The entire protocol takes ~7 d from transposition induction to having a final library ready for sequencing. This protocol is highly efficient and less labor intensive than alternative approaches and significantly accelerates genetic studies of Candida.
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9
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Truong T, Zeng G, Lim TK, Cao T, Pang LM, Lee YM, Lin Q, Wang Y, Seneviratne CJ. Proteomics Analysis ofCandida albicans dnm1Haploid Mutant Unraveled the Association between Mitochondrial Fission and Antifungal Susceptibility. Proteomics 2019; 20:e1900240. [DOI: 10.1002/pmic.201900240] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 11/05/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Thuyen Truong
- Oral Sciences, Faculty of DentistryNational University of Singapore 9 Lower Kent Ridge Road Singapore 119085
| | - Guisheng Zeng
- Institute of Molecular and Cell BiologyAgency for Science, Technology and Research 61 Biopolis Drive, Proteos Singapore 138673
| | - Teck Kwang Lim
- Department of Biological SciencesFaculty of Science, National University of Singapore 16 Science Drive 4, S2 Singapore 117558
| | - Tong Cao
- Oral Sciences, Faculty of DentistryNational University of Singapore 9 Lower Kent Ridge Road Singapore 119085
| | - Li Mei Pang
- National Dental Research Institute SingaporeSinghealth Duke NUS, Singapore 5 Second Hospital Ave Singapore 168938
| | - Yew Mun Lee
- Department of Biological SciencesFaculty of Science, National University of Singapore 16 Science Drive 4, S2 Singapore 117558
| | - Qingsong Lin
- Department of Biological SciencesFaculty of Science, National University of Singapore 16 Science Drive 4, S2 Singapore 117558
| | - Yue Wang
- Institute of Molecular and Cell BiologyAgency for Science, Technology and Research 61 Biopolis Drive, Proteos Singapore 138673
- Department of Biochemistry, Yong Loo Lin School of MedicineNational University of Singapore 10 Medical Dr Singapore 117597
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10
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Chen T, Wagner AS, Tams RN, Eyer JE, Kauffman SJ, Gann ER, Fernandez EJ, Reynolds TB. Lrg1 Regulates β (1,3)-Glucan Masking in Candida albicans through the Cek1 MAP Kinase Pathway. mBio 2019; 10:e01767-19. [PMID: 31530671 PMCID: PMC6751057 DOI: 10.1128/mbio.01767-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/15/2019] [Indexed: 12/28/2022] Open
Abstract
Candida albicans is among the most prevalent opportunistic human fungal pathogens. The ability to mask the immunogenic polysaccharide β (1,3)-glucan from immune detection via a layer of mannosylated proteins is a key virulence factor of C. albicans We previously reported that hyperactivation of the Cek1 mitogen-activated protein (MAP) kinase pathway promotes β (1,3)-glucan exposure. In this communication, we report a novel upstream regulator of Cek1 activation and characterize the impact of Cek1 activity on fungal virulence. Lrg1 encodes a GTPase-activating protein (GAP) that has been suggested to inhibit the GTPase Rho1. We found that disruption of LRG1 causes Cek1 hyperactivation and β (1,3)-glucan unmasking. However, when GTPase activation was measured for a panel of GTPases, the lrg1ΔΔ mutant exhibited increased activation of Cdc42 and Ras1 but not Rho1 or Rac1. Unmasking and Cek1 activation in the lrg1ΔΔ mutant can be blocked by inhibition of the Ste11 MAP kinase kinase kinase (MAPKKK), indicating that the lrg1ΔΔ mutant acts through the canonical Cek1 MAP kinase cascade. In order to determine how Cek1 hyperactivation specifically impacts virulence, a doxycycline-repressible hyperactive STE11ΔN467 allele was expressed in C. albicans In the absence of doxycycline, this allele overexpressed STE11ΔN467 , which induced production of proinflammatory tumor necrosis factor alpha (TNF-α) from murine macrophages. This in vitro phenotype correlates with decreased colonization and virulence in a mouse model of systemic infection. The mechanism by which Ste11ΔN467 causes unmasking was explored with RNA sequencing (RNA-Seq) analysis. Overexpression of Ste11ΔN467 caused upregulation of the Cph1 transcription factor and of a group of cell wall-modifying proteins which are predicted to impact cell wall architecture.IMPORTANCECandida albicans is an important source of systemic infections in humans. The ability to mask the immunogenic cell wall polymer β (1,3)-glucan from host immune surveillance contributes to fungal virulence. We previously reported that the hyperactivation of the Cek1 MAP kinase cascade promotes cell wall unmasking, thus increasing strain immunogenicity. In this study, we identified a novel regulator of the Cek1 pathway called Lrg1. Lrg1 is a predicted GTPase-activating protein (GAP) that represses Cek1 activity by downregulating the GTPase Cdc42 and its downstream MAPKKK, Ste11. Upregulation of Cek1 activity diminished fungal virulence in the mouse model of infection, and this correlates with increased cytokine responses from macrophages. We also analyzed the transcriptional profile determined during β (1,3)-glucan exposure driven by Cek1 hyperactivation. Our report provides a model where Cek1 hyperactivation causes β (1,3)-glucan exposure by upregulation of cell wall proteins and leads to more robust immune detection in vivo, promoting more effective clearance.
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Affiliation(s)
- Tian Chen
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Andrew S Wagner
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Robert N Tams
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
| | - James E Eyer
- Department of Biochemistry & Cellular and Molecular Biology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Sarah J Kauffman
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Eric R Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Elias J Fernandez
- Department of Biochemistry & Cellular and Molecular Biology, The University of Tennessee, Knoxville, Tennessee, USA
| | - Todd B Reynolds
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, USA
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11
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Truong T, Suriyanarayanan T, Zeng G, Le TD, Liu L, Li J, Tong C, Wang Y, Seneviratne CJ. Use of Haploid Model of Candida albicans to Uncover Mechanism of Action of a Novel Antifungal Agent. Front Cell Infect Microbiol 2018; 8:164. [PMID: 29938200 PMCID: PMC6002804 DOI: 10.3389/fcimb.2018.00164] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/01/2018] [Indexed: 11/13/2022] Open
Abstract
Antifungal agents for the treatment of Candida albicans infections are limited. We recently discovered a novel antifungal small molecule, SM21, with promising in vivo activity. Herein, we employed the newly developed C. albicans haploid toolbox to uncover the mechanism of action of SM21. Comprehensive RNA-Seq analyses of the haploid susceptible GZY803 strain revealed significant gene expression changes related to mitochondria when exposed to SM21. Mitochondrial structure visualization and measurement of ATP generation, reactive oxygen species (ROS) levels, and the antioxidant potential of SM21-treated and untreated GZY803, mitochondrial structure defective haploid mutant (dnm1Δ), and wild-type diploid SC5314 strains confirmed defects in mitochondria. Exploiting the advantage of C. albicans haploids as a single ploidy model, we further exposed GZY803 to repetitive treatments of SM21 in order to generate resistant mutants. Three colonies designated S3, S5 and S6, which displayed resistance to SM21, were isolated. All resistant strains exhibited enhanced transcriptomic responses for peptide and protein metabolism and secreted aspartate proteases (SAPs) activity under SM21 treatment compared to the parent strain GZY803. Consistently, supplementing the resistant strains, GZY803, and SC5314 with peptone, a form of digested peptides, decreased susceptibility to SM21. The present study demonstrates the usefulness of haploid C. albicans model in antifungal drug discovery. The findings will be invaluable to develop SM21 as a novel antifungal agent, which will benefit millions of patients suffering from Candida infections.
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Affiliation(s)
- Thuyen Truong
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | | | - Guisheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - Thuc D Le
- School of Information Technology and Mathematical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Lin Liu
- School of Information Technology and Mathematical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Jiuyong Li
- School of Information Technology and Mathematical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Cao Tong
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Chaminda J Seneviratne
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore, Singapore
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12
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Sac7 and Rho1 regulate the white-to-opaque switching in Candida albicans. Sci Rep 2018; 8:875. [PMID: 29343748 PMCID: PMC5772354 DOI: 10.1038/s41598-018-19246-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/19/2017] [Indexed: 11/17/2022] Open
Abstract
Candida albicans cells homozygous at the mating-type locus stochastically undergo the white-to-opaque switching to become mating-competent. This switching is regulated by a core circuit of transcription factors organized through interlocking feedback loops around the master regulator Wor1. Although a range of distinct environmental cues is known to induce the switching, the pathways linking the external stimuli to the central control mechanism remains largely unknown. By screening a C. albicans haploid gene-deletion library, we found that SAC7 encoding a GTPase-activating protein of Rho1 is required for the white-to-opaque switching. We demonstrate that Sac7 physically associates with Rho1-GTP and the constitutively active Rho1G18V mutant impairs the white-to-opaque switching while the inactive Rho1D124A mutant promotes it. Overexpressing WOR1 in both sac7Δ/Δ and rho1G18V cells suppresses the switching defect, indicating that the Sac7/Rho1 module acts upstream of Wor1. Furthermore, we provide evidence that Sac7/Rho1 functions in a pathway independent of the Ras/cAMP pathway which has previously been positioned upstream of Wor1. Taken together, we have discovered new regulators and a signaling pathway that regulate the white-to-opaque switching in the most prevalent human fungal pathogen C. albicans.
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13
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Ellepola K, Liu Y, Cao T, Koo H, Seneviratne CJ. Bacterial GtfB Augments Candida albicans Accumulation in Cross-Kingdom Biofilms. J Dent Res 2017; 96:1129-1135. [PMID: 28605597 DOI: 10.1177/0022034517714414] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Streptococcus mutans is a biofilm-forming oral pathogen commonly associated with dental caries. Clinical studies have shown that S. mutans is often detected with Candida albicans in early childhood caries. Although the C. albicans presence has been shown to enhance bacterial accumulation in biofilms, the influence of S. mutans on fungal biology in this mixed-species relationship remains largely uncharacterized. Therefore, we aimed to investigate how the presence of S. mutans influences C. albicans biofilm development and coexistence. Using a newly established haploid biofilm model of C. albicans, we found that S. mutans augmented haploid C. albicans accumulation in mixed-species biofilms. Similarly, diploid C. albicans also showed enhanced biofilm formation in the presence of S. mutans. Surprisingly, the presence of S. mutans restored the biofilm-forming ability of C. albicans bcr1Δ mutant and bcr1Δ/Δ mutant, which is known to be severely defective in biofilm formation when grown as single species. Moreover, C. albicans hyphal growth factor HWP1 as well as ALS1 and ALS3, which are also involved in fungal biofilm formation, were upregulated in the presence of S. mutans. Subsequently, we found that S. mutans-derived glucosyltransferase B (GtfB) itself can promote C. albicans biofilm development. Interestingly, GtfB was able to increase the expression of HWP1, ALS1, and ALS3 genes in the C. albicans diploid wild-type SC5314 and bcr1Δ/Δ, leading to enhanced fungal biofilms. Hence, the present study demonstrates that a bacterial exoenzyme (GtfB) augments the C. albicans counterpart in mixed-species biofilms through a BCR1-independent mechanism. This novel finding may explain the mutualistic role of S. mutans and C. albicans in cariogenic biofilms.
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Affiliation(s)
- K Ellepola
- 1 Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore
| | - Y Liu
- 2 Biofilm Research Labs, Levy Center for Oral Health, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, School of Dental Medicine, University of Pennsylvania, PA, USA
| | - T Cao
- 1 Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore
| | - H Koo
- 2 Biofilm Research Labs, Levy Center for Oral Health, Department of Orthodontics and Divisions of Pediatric Dentistry & Community Oral Health, School of Dental Medicine, University of Pennsylvania, PA, USA
| | - C J Seneviratne
- 1 Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore
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14
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Giongo JL, de Almeida Vaucher R, Fausto VP, Quatrin PM, Lopes LQS, Santos RCV, Gündel A, Gomes P, Steppe M. Anti- Candida activity assessment of Pelargonium graveolens oil free and nanoemulsion in biofilm formation in hospital medical supplies. Microb Pathog 2016; 100:170-178. [DOI: 10.1016/j.micpath.2016.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/20/2016] [Accepted: 08/04/2016] [Indexed: 11/27/2022]
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15
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Truong T, Zeng G, Qingsong L, Kwang LT, Tong C, Chan FY, Wang Y, Seneviratne CJ. Comparative Ploidy Proteomics of Candida albicans Biofilms Unraveled the Role of the AHP1 Gene in the Biofilm Persistence Against Amphotericin B. Mol Cell Proteomics 2016; 15:3488-3500. [PMID: 27644984 DOI: 10.1074/mcp.m116.061523] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Indexed: 01/23/2023] Open
Abstract
Candida albicans is a major fungal pathogen causing lethal infections in immunocompromised patients. C. albicans forms antifungal tolerant biofilms contributing significantly to therapeutic failure. The recently established haploid C. albicans biofilm model provides a new toolbox to uncover the mechanism governing the higher antifungal tolerance of biofilms. Here, we comprehensively examined the proteomics and antifungal susceptibility of standard diploid (SC5314 and BWP17) and stable haploid (GZY792 and GZY803) strains of C. albicans biofilms. Subsequent downstream analyses identified alkyl hydroperoxide reductase 1 (AHP1) as a critical determinant of C. albicans biofilm's tolerance of amphotericin B. At 32 μg/ml of amphotericin B, GZY803 haploid biofilms showed 0.1% of persister population as compared with 1% of the diploid biofilms. AHP1 expression was found to be lower in GZY803 biofilms, and AHP1 overexpression in GZY803 restored the percentage of persister population. Consistently, deleting AHP1 in the diploid strain BWP17 caused a similar increase in amphotericin B susceptibility. AHP1 expression was also positively correlated with the antioxidant potential. Furthermore, C. albicans ira2Δ/Δ biofilms were susceptible to amphotericin B and had a diminished antioxidant capacity. Interestingly, AHP1 overexpression in the ira2Δ/Δ strain restored the antioxidant potential and enhanced the persister population against amphotericin B, and shutting down the AHP1 expression in ira2Δ/Δ biofilms reversed the effect. In conclusion, we provide evidence that the AHP1 gene critically determines the amphotericin B tolerance of C. albicans biofilms possibly by maintaining the persisters' antioxidant capacity. This finding will open up new avenues for developing therapies targeting the persister population of C. albicans biofilms. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD004274.
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Affiliation(s)
- Thuyen Truong
- From the ‡Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119083
| | - Guisheng Zeng
- the §Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 138673, and
| | - Lin Qingsong
- the ¶Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
| | - Lim Teck Kwang
- the ¶Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543
| | - Cao Tong
- From the ‡Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119083
| | - Fong Yee Chan
- the §Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 138673, and
| | - Yue Wang
- the §Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 138673, and
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