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Wang Z, Zhang Q, Zhang H, Lu Y. Roles of alcohol dehydrogenase 1 in the biological activities of Candida albicans. Crit Rev Microbiol 2024:1-15. [PMID: 38916139 DOI: 10.1080/1040841x.2024.2371510] [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: 11/17/2023] [Accepted: 06/04/2024] [Indexed: 06/26/2024]
Abstract
Candida albicans stands as the foremost prevalent human commensal pathogen and a significant contributor to nosocomial fungal infections. In the metabolism of C. albicans, alcohol dehydrogenase 1 (Adh1) is one of the important enzymes that converts acetaldehyde produced by pyruvate decarboxylation into ethanol at the end of glycolysis. Leveraging the foundational processes of alcoholic fermentation, Adh1 plays an active role in multiple biological phenomena, including biofilm formation, interactions between different species, the development of drug resistance, and the potential initiation of gastrointestinal cancer. Additionally, Adh1 within C. albicans has demonstrated associations with regulating the cell cycle, stress responses, and various intracellular states. Furthermore, Adh1 is extracellularly localized on the cell wall surface, where it plays roles in processes such as tissue invasion and host immune responses. Drawing from an analysis of ADH1 gene structure, expression patterns, and fundamental functions, this review elucidates the intricate connections between Adh1 and various biological processes within C. albicans, underscoring its potential implications for the prevention, diagnosis, and treatment of candidiasis.
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Affiliation(s)
- Ziqi Wang
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, China
| | - Qi Zhang
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, China
| | - Haoying Zhang
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, China
| | - Yuanyuan Lu
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, China
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Zheng Q, Xin J, Zhao C, Tian R. Role of methylglyoxal and glyoxalase in the regulation of plant response to heavy metal stress. PLANT CELL REPORTS 2024; 43:103. [PMID: 38502356 DOI: 10.1007/s00299-024-03186-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/26/2024] [Indexed: 03/21/2024]
Abstract
KEY MESSAGE Methylglyoxal and glyoxalase function a significant role in plant response to heavy metal stress. We update and discuss the most recent developments of methylglyoxal and glyoxalase in regulating plant response to heavy metal stress. Methylglyoxal (MG), a by-product of several metabolic processes, is created by both enzymatic and non-enzymatic mechanisms. It plays an important role in plant growth and development, signal transduction, and response to heavy metal stress (HMS). Changes in MG content and glyoxalase (GLY) activity under HMS imply that they may be potential biomarkers of plant stress resistance. In this review, we summarize recent advances in research on the mechanisms of MG and GLY in the regulation of plant responses to HMS. It has been discovered that appropriate concentrations of MG assist plants in maintaining a balance between growth and development and survival defense, therefore shielding them from heavy metal harm. MG and GLY regulate plant physiological processes by remodeling cellular redox homeostasis, regulating stomatal movement, and crosstalking with other signaling molecules (including abscisic acid, gibberellic acid, jasmonic acid, cytokinin, salicylic acid, melatonin, ethylene, hydrogen sulfide, and nitric oxide). We also discuss the involvement of MG and GLY in the regulation of plant responses to HMS at the transcriptional, translational, and metabolic levels. Lastly, considering the current state of research, we present a perspective on the future direction of MG research to elucidate the MG anti-stress mechanism and offer a theoretical foundation and useful advice for the remediation of heavy metal-contaminated environments in the future.
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Affiliation(s)
- Qianqian Zheng
- College of Architecture Landscape, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| | - Jianpan Xin
- College of Architecture Landscape, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| | - Chu Zhao
- College of Architecture Landscape, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
| | - Runan Tian
- College of Architecture Landscape, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China.
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Schruefer S, Pschibul A, Wong SSW, Sae-Ong T, Wolf T, Schäuble S, Panagiotou G, Brakhage AA, Aimanianda V, Kniemeyer O, Ebel F. Distinct transcriptional responses to fludioxonil in Aspergillus fumigatus and its ΔtcsC and Δskn7 mutants reveal a crucial role for Skn7 in the cell wall reorganizations triggered by this antifungal. BMC Genomics 2023; 24:684. [PMID: 37964194 PMCID: PMC10647056 DOI: 10.1186/s12864-023-09777-5] [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: 03/10/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023] Open
Abstract
BACKGROUND Aspergillus fumigatus is a major fungal pathogen that causes severe problems due to its increasing resistance to many therapeutic agents. Fludioxonil is a compound that triggers a lethal activation of the fungal-specific High Osmolarity Glycerol pathway. Its pronounced antifungal activity against A. fumigatus and other pathogenic molds renders this agent an attractive lead substance for the development of new therapeutics. The group III hydride histidine kinase TcsC and its downstream target Skn7 are key elements of the multistep phosphorelay that represents the initial section of the High Osmolarity Glycerol pathway. Loss of tcsC results in resistance to fludioxonil, whereas a Δskn7 mutant is partially, but not completely resistant. RESULTS In this study, we compared the fludioxonil-induced transcriptional responses in the ΔtcsC and Δskn7 mutant and their parental A. fumigatus strain. The number of differentially expressed genes correlates well with the susceptibility level of the individual strains. The wild type and, to a lesser extend also the Δskn7 mutant, showed a multi-faceted stress response involving genes linked to ribosomal and peroxisomal function, iron homeostasis and oxidative stress. A marked difference between the sensitive wild type and the largely resistant Δskn7 mutant was evident for many cell wall-related genes and in particular those involved in the biosynthesis of chitin. Biochemical data corroborate this differential gene expression that does not occur in response to hyperosmotic stress. CONCLUSIONS Our data reveal that fludioxonil induces a strong and TcsC-dependent stress that affects many aspects of the cellular machinery. The data also demonstrate a link between Skn7 and the cell wall reorganizations that foster the characteristic ballooning and the subsequent lysis of fludioxonil-treated cells.
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Affiliation(s)
- Sebastian Schruefer
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany
| | - Annica Pschibul
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Sarah Sze Wah Wong
- UMR2000, Molecular Mycology Unit, Mycology Department, Institut Pasteur, Université Paris Cité, CNRS, Paris, France
| | - Tongta Sae-Ong
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Thomas Wolf
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Sascha Schäuble
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Gianni Panagiotou
- Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Axel A Brakhage
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Vishukumar Aimanianda
- UMR2000, Molecular Mycology Unit, Mycology Department, Institut Pasteur, Université Paris Cité, CNRS, Paris, France
- Institut Pasteur, Université Paris Cité, Immunobiology of Aspergillus, Mycology Department, Paris, France
| | - Olaf Kniemeyer
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Frank Ebel
- Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany.
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de Almeida GRL, Szczepanik JC, Selhorst I, Cunha MP, Dafre AL. The expanding impact of methylglyoxal on behavior-related disorders. Prog Neuropsychopharmacol Biol Psychiatry 2023; 120:110635. [PMID: 36103947 DOI: 10.1016/j.pnpbp.2022.110635] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/02/2022] [Accepted: 09/07/2022] [Indexed: 01/17/2023]
Abstract
Methylglyoxal (MGO) is a reactive dicarbonyl compound formed as a byproduct of glycolysis. MGO is a major cell-permeant precursor of advanced glycation end products (AGEs), since it readily reacts with basic phospholipids and nucleotides, as well as amino acid residues of proteins, such as arginine, cysteine, and lysine. The AGEs production induced by MGO are widely associated with several pathologies, including neurodegenerative diseases. However, the impact of MGO metabolism and AGEs formation in the central nervous system (particularly in neurons, astrocytes and oligodendrocytes) on behavior and psychiatric diseases is not fully understood. Here, we briefly present background information on the biological activity of MGO in the central nervous system. It was gathered the available information on the role of MGO metabolism at the physiological processes, as well as at the neurobiology of psychiatry diseases, especially pain-related experiences, anxiety, depression, and cognition impairment-associated diseases. To clarify the role of MGO on behavior and associated diseases, we reviewed primarily the main findings at preclinical studies focusing on genetic and pharmacological approaches. Since monoamine neurotransmitter systems are implicated as pivotal targets on the pathophysiology and treatment of psychiatry and cognitive-related diseases, we also reviewed how MGO affects these neurotransmission systems and the implications of this phenomenon for nociception and pain; learning and cognition; and mood. In summary, this review highlights the pivotal role of glyoxalase 1 (Glo1) and MGO levels in modulating behavioral phenotypes, as well as related cellular and molecular signaling. Conclusively, this review signals dopamine as a new neurochemical MGO target, as well as highlights how MGO metabolism can modulate the pathophysiology and treatment of pain, psychiatric and cognitive-related diseases.
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Affiliation(s)
- Gudrian R L de Almeida
- Department of Biochemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil
| | - Jozimar C Szczepanik
- Department of Biochemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil
| | - Ingrid Selhorst
- Department of Biochemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil
| | - Mauricio P Cunha
- Department of Biochemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil; Department of Basic Sciences of Life, Federal University of Juiz de Fora, 35010-177 Governador Valadares, MG, Brazil.
| | - Alcir L Dafre
- Department of Biochemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil
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Demers EG, Stajich JE, Ashare A, Occhipinti P, Hogan DA. Balancing Positive and Negative Selection: In Vivo Evolution of Candida lusitaniae MRR1. mBio 2021; 12:e03328-20. [PMID: 33785623 PMCID: PMC8092287 DOI: 10.1128/mbio.03328-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
The evolution of pathogens in response to selective pressures present during chronic infections can influence their persistence and virulence and the outcomes of antimicrobial therapy. Because subpopulations within an infection can be spatially separated and the host environment can fluctuate, an appreciation of the pathways under selection may be most easily revealed through the analysis of numerous isolates from single infections. Here, we continued our analysis of a set of clonally derived Clavispora (Candida) lusitaniae isolates from a single chronic lung infection with a striking enrichment in the number of alleles of MRR1 Genetic and genomic analyses found evidence for repeated acquisition of gain-of-function mutations that conferred constitutive Mrr1 activity. In the same population, there were multiple alleles with both gain-of-function mutations and secondary suppressor mutations that either attenuated or abolished the constitutive activity, suggesting the presence of counteracting selective pressures. Our studies demonstrated trade-offs between high Mrr1 activity, which confers resistance to the antifungal fluconazole, host factors, and bacterial products through its regulation of MDR1, and resistance to hydrogen peroxide, a reactive oxygen species produced in the neutrophilic environment associated with this infection. This inverse correlation between high Mrr1 activity and hydrogen peroxide resistance was observed in multiple Candida species and in serially collected populations from this individual over 3 years. These data lead us to propose that dynamic or variable selective pressures can be reflected in population genomics and that these dynamics can complicate the drug resistance profile of the population.IMPORTANCE Understanding microbial evolution within patients is critical for managing chronic infections and understanding host-pathogen interactions. Here, our analysis of multiple MRR1 alleles in isolates from a single Clavispora (Candida) lusitaniae infection revealed the selection for both high and low Mrr1 activity. Our studies reveal trade-offs between high Mrr1 activity, which confers resistance to the commonly used antifungal fluconazole, host antimicrobial peptides, and bacterial products, and resistance to hydrogen peroxide. This work suggests that spatial or temporal differences within chronic infections can support a large amount of dynamic and parallel evolution and that Mrr1 activity is under both positive and negative selective pressure to balance different traits that are important for microbial survival.
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Affiliation(s)
- Elora G Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jason E Stajich
- Department of Microbiology & Plant Pathology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
| | - Alix Ashare
- Dartmouth-Hitchcock Medical Center, Section of Pulmonary and Critical Care Medicine, Lebanon, New Hampshire, USA
| | - Patricia Occhipinti
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Kang SO, Kwak MK. Methylglyoxal-Scavenging Enzyme Activities Trigger Erythroascorbate Peroxidase and Cytochrome c Peroxidase in Glutathione-Depleted Candida albicans. J Microbiol Biotechnol 2021; 31:79-91. [PMID: 33203822 PMCID: PMC9705698 DOI: 10.4014/jmb.2010.10057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/15/2022]
Abstract
γ-Glutamylcysteine synthetase (Gcs1) and glutathione reductase (Glr1) activity maintains minimal levels of cellular methylglyoxal in Candida albicans. In glutathione-depleted Δgcs1, we previously saw that NAD(H)-linked methylglyoxal oxidoreductase (Mgd1) and alcohol dehydrogenase (Adh1) are the most active methylglyoxal scavengers. With methylglyoxal accumulation, disruptants lacking MGD1 or ADH1 exhibit a poor redox state. However, there is little convincing evidence for a reciprocal relationship between methylglyoxal scavenger genes-disrupted mutants and changes in glutathione-(in)dependent redox regulation. Herein, we attempt to demonstrate a functional role for methylglyoxal scavengers, modeled on a triple disruptant (Δmgd1/Δadh1/Δgcs1), to link between antioxidative enzyme activities and their metabolites in glutathione-depleted conditions. Despite seeing elevated methylglyoxal in all of the disruptants, the result saw a decrease in pyruvate content in Δmgd1/Δadh1/Δgcs1 which was not observed in double gene-disrupted strains such as Δmgd1/Δgcs1 and Δadh1/Δgcs1. Interestingly, Δmgd1/Δadh1/Δgcs1 exhibited a significantly decrease in H2O2 and superoxide which was also unobserved in Δmgd1/Δgcs1 and Δadh1/Δgcs1. The activities of the antioxidative enzymes erythroascorbate peroxidase and cytochrome c peroxidase were noticeably higher in Δmgd1/Δadh1/Δgcs1 than in the other disruptants. Meanwhile, Glr1 activity severely diminished in Δmgd1/Δadh1/Δgcs1. Monitoring complementary gene transcripts between double gene-disrupted Δmgd1/Δgcs1 and Δadh1/Δgcs1 supported the concept of an unbalanced redox state independent of the Glr1 activity for Δmgd1/Δadh1/Δgcs1. Our data demonstrate the reciprocal use of Eapx1 and Ccp1 in the absence of both methylglyoxal scavengers; that being pivotal for viability in non-filamentous budding yeast.
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Affiliation(s)
- Sa-Ouk Kang
- Laboratory of Biophysics, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea,Corresponding authors S-O.Kang Phone: +82-2-880-6703 Fax: +82-2-888-4911 E-mail:
| | - Min-Kyu Kwak
- Department of Food and Nutrition, Institute of Food and Nutrition Science, Eulji University, Seongnam 13135, Republic of Korea,M-K.Kwak Phone: +82-31-740-7418 Fax: +82-31-740-7370 E-mail:
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7
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Kang SO, Kwak MK. Alcohol dehydrogenase 1 and NAD(H)-linked methylglyoxal oxidoreductase reciprocally regulate glutathione-dependent enzyme activities in Candida albicans. J Microbiol 2020; 59:76-91. [PMID: 33355888 DOI: 10.1007/s12275-021-0552-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/09/2020] [Accepted: 11/09/2020] [Indexed: 11/27/2022]
Abstract
Glutathione reductase (Glr1) activity controls cellular glutathione and reactive oxygen species (ROS). We previously demonstrated two predominant methylglyoxal scavengers-NAD(H)-linked methylglyoxal oxidoreductase (Mgd1) and alcohol dehydrogenase 1 (Adh1)-in glutathione-depleted γ-glutamyl cysteinyl synthetase-disrupted Candida albicans. However, experimental evidence for Candida pathophysiology lacking the enzyme activities of Mgd1 and Adh1 on glutathione-dependent redox regulation remains unclear. Herein, we have aimed to demonstrate that glutathione-dependent enzyme activities coupled with cellular ROS changes is regulated by methylglyoxal accumulation in Δmgd1/Δadh1 double disruptants. Δmgd1/Δadh1 showed severe growth defects and G1-phase cell cycle arrest. The observed complementary and reciprocal methylglyoxal-oxidizing and methylglyoxalreducing activities between Δmgd1 and Δadh1 were not always exhibited in Δmgd1/Δadh1. Although intracellular accumulation of methylglyoxal and pyruvate was shown in all disruptants, to a greater or lesser degree, methylglyoxal was particularly accumulated in the Δmgd1/Δadh1 double disruptant. While cellular ROS significantly increased in Δmgd1 and Δadh1 as compared to the wild-type, Δmgd1/Δadh1 underwent a decrease in ROS in contrast to Δadh1. Despite the experimental findings underlining the importance of the undergoing unbalanced redox state of Δmgd1/Δadh1, glutathione-independent antioxidative enzyme activities did not change during proliferation and filamentation. Contrary to the significantly lowered glutathione content and Glr1 enzyme activity, the activity staining-based glutathione peroxidase activities concomitantly increased in this mutant. Additionally, the enhanced GLR1 transcript supported our results in Δmgd1/Δadh1, indicating that deficiencies of both Adh1 and Mgd1 activities stimulate specific glutathione-dependent enzyme activities. This suggests that glutathione-dependent redox regulation is evidently linked to C. albicans pathogenicity under the control of methylglyoxal-scavenging activities.
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Affiliation(s)
- Sa-Ouk Kang
- Laboratory of Biophysics, School of Biological Sciences, and Institute of Microbiology, Seoul National University, Seoul, 08826, Republic of Korea.
- Present address: Irwee Institute, B-503, Seongnam, 13510, Republic of Korea.
| | - Min-Kyu Kwak
- Department of Food and Nutrition, Institute of Food and Nutrition Science, Eulji University, Seongnam, 13135, Republic of Korea.
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Biermann AR, Demers EG, Hogan DA. Mrr1 regulation of methylglyoxal catabolism and methylglyoxal-induced fluconazole resistance in Candida lusitaniae. Mol Microbiol 2020; 115:116-130. [PMID: 33319423 DOI: 10.1111/mmi.14604] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/26/2020] [Accepted: 09/05/2020] [Indexed: 12/11/2022]
Abstract
Transcription factor Mrr1, best known for its regulation of Candida azole resistance genes such as MDR1, regulates other genes that are poorly characterized. Among the other Mrr1-regulated genes are putative methylglyoxal reductases. Methylglyoxal (MG) is a toxic metabolite that is elevated in diabetes, uremia, and sepsis, which are diseases that increase the risk for candidiasis, and MG serves as a regulatory signal in diverse organisms. Our studies in Clavispora lusitaniae, also known as Candida lusitaniae, showed that Mrr1 regulates expression of two paralogous MG reductases, MGD1 and MGD2, and that both participate in MG resistance and MG catabolism. Exogenous MG increased Mrr1-dependent expression of MGD1 and MGD2 as well as expression of MDR1, which encodes an efflux pump that exports fluconazole. MG improved growth in the presence of fluconazole and this was largely Mrr1-dependent with contributions from a secondary transcription factor, Cap1. Increased fluconazole resistance was also observed in mutants lacking Glo1, a Mrr1-independent MG catabolic enzyme. Isolates from other Candida species displayed heterogeneity in MG resistance and MG stimulation of azole resistance. We propose endogenous and host-derived MG can induce MDR1 and other Mrr1-regulated genes causing increased drug resistance, which may contribute to some instances of fungal treatment failure.
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Affiliation(s)
- Amy R Biermann
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Elora G Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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Conditional antagonism in co-cultures of Pseudomonas aeruginosa and Candida albicans: An intersection of ethanol and phosphate signaling distilled from dual-seq transcriptomics. PLoS Genet 2020; 16:e1008783. [PMID: 32813693 PMCID: PMC7480860 DOI: 10.1371/journal.pgen.1008783] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 09/09/2020] [Accepted: 06/20/2020] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa and Candida albicans are opportunistic pathogens whose interactions involve the secreted products ethanol and phenazines. Here, we describe the role of ethanol in mixed-species co-cultures by dual-seq analyses. P. aeruginosa and C. albicans transcriptomes were assessed after growth in mono-culture or co-culture with either ethanol-producing C. albicans or a C. albicans mutant lacking the primary ethanol dehydrogenase, Adh1. Analysis of the RNA-Seq data using KEGG pathway enrichment and eADAGE methods revealed several P. aeruginosa responses to C. albicans-produced ethanol including the induction of a non-canonical low-phosphate response regulated by PhoB. C. albicans wild type, but not C. albicans adh1Δ/Δ, induces P. aeruginosa production of 5-methyl-phenazine-1-carboxylic acid (5-MPCA), which forms a red derivative within fungal cells and exhibits antifungal activity. Here, we show that C. albicans adh1Δ/Δ no longer activates P. aeruginosa PhoB and PhoB-regulated phosphatase activity, that exogenous ethanol complements this defect, and that ethanol is sufficient to activate PhoB in single-species P. aeruginosa cultures at permissive phosphate levels. The intersection of ethanol and phosphate in co-culture is inversely reflected in C. albicans; C. albicans adh1Δ/Δ had increased expression of genes regulated by Pho4, the C. albicans transcription factor that responds to low phosphate, and Pho4-dependent phosphatase activity. Together, these results show that C. albicans-produced ethanol stimulates P. aeruginosa PhoB activity and 5-MPCA-mediated antagonism, and that both responses are dependent on local phosphate concentrations. Further, our data suggest that phosphate scavenging by one species improves phosphate access for the other, thus highlighting the complex dynamics at play in microbial communities. Pseudomonas aeruginosa and Candida albicans are opportunistic pathogens that are frequently isolated from co-infections. Using a combination of dual-seq transcriptomics and genetics approaches, we found that ethanol produced by C. albicans stimulates the PhoB regulon in P. aeruginosa asynchronously with activation of the Pho4 regulon in C. albicans. We validated our result by showing that PhoB plays multiple roles in co-culture including orchestrating the competition for phosphate and the production of 5-methyl-phenazine-1-carboxylic acid; the P. aeruginosa phenazine response to C. albicans-produced ethanol depends on phosphate availability. The conditional stimulation of antifungal production in response to sub-inhibitory concentrations of ethanol only under phosphate limitation highlights the importance of considering nutrient concentrations in the analysis of co-culture interactions and suggests that the low-phosphate response in one species influences phosphate availability for the other.
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