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Cabrera IE, Oza Y, Carrillo AJ, Collier LA, Wright SJ, Li L, Borkovich KA. Regulator of G Protein Signaling Proteins Control Growth, Development and Cellulase Production in Neurospora crassa. J Fungi (Basel) 2022; 8:jof8101076. [PMID: 36294641 PMCID: PMC9604755 DOI: 10.3390/jof8101076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/05/2022] [Accepted: 10/11/2022] [Indexed: 11/30/2022] Open
Abstract
Heterotrimeric (αβγ) G protein signaling pathways are critical environmental sensing systems found in eukaryotic cells. Exchange of GDP for GTP on the Gα subunit leads to its activation. In contrast, GTP hydrolysis on the Gα is accelerated by Regulator of G protein Signaling (RGS) proteins, resulting in a return to the GDP-bound, inactive state. Here, we analyzed growth, development and extracellular cellulase production in strains with knockout mutations in the seven identified RGS genes (rgs-1 to rgs-7) in the filamentous fungus, Neurospora crassa. We compared phenotypes to those of strains with either knockout mutations or expressing predicted constitutively activated, GTPase-deficient alleles for each of the three Gα subunit genes (gna-1Q204L, gna-2Q205L or gna-3Q208L). Our data revealed that six RGS mutants have taller aerial hyphae than wild type and all seven mutants exhibit reduced asexual sporulation, phenotypes shared with strains expressing the gna-1Q204L or gna-3Q208L allele. In contrast, Δrgs-1 and Δrgs-3 were the only RGS mutants with a slower growth rate phenotype, a defect in common with gna-1Q204L strains. With respect to female sexual development, Δrgs-1 possessed defects most similar to gna-3Q208L strains, while those of Δrgs-2 mutants resembled strains expressing the gna-1Q204L allele. Finally, we observed that four of the seven RGS mutants had significantly different extracellular cellulase levels relative to wild type. Of interest, the Δrgs-2 mutant had no detectable activity, similar to the gna-3Q208L strain. In contrast, the Δrgs-1 and Δrgs-4 mutants and gna-1Q204L and gna-2Q205L strains exhibited significantly higher cellulase activity than wild type. With the exception of sexual development, our results demonstrate the greatest number of genetic interactions between rgs-1 and gna-1 and rgs-2 and gna-3 in N. crassa.
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Gan T, An H, Tang M, Chen H. Phylogeny of Regulators of G-Protein Signaling Genes in Leptographium qinlingensis and Expression Levels of Three RGSs in Response to Different Terpenoids. Microorganisms 2022; 10:microorganisms10091698. [PMID: 36144299 PMCID: PMC9506272 DOI: 10.3390/microorganisms10091698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/16/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
Leptographium qinlingensis is a bark beetle-vectored pine pathogen in the Chinese white pine beetle (Dendroctonus armandi) epidemic in Northwest China. L. qinlingensis colonizes pines despite the trees’ massive oleoresin terpenoid defenses. Regulators of G-protein signaling (RGS) proteins modulate heterotrimeric G-protein signaling negatively and play multiple roles in the growth, asexual development, and pathogenicity of fungi. In this study, we have identified three L. qinlingensis RGS genes, and the phylogenetic analysis shows the highest homology with the regulators of G-protein signaling proteins sequence from Ophiostoma piceae and Grosmannia clavigera. The expression profiles of three RGSs in the mycelium of L. qinlingensis treated with six different terpenoids were detected, as well as their growth rates. Under six terpenoid treatments, the growth and reproduction in L. qinlingensis were significantly inhibited, and the growth inflection day was delayed from 8 days to 12–13 days. By analyzing the expression level of three RGS genes of L. qinlingensis with different treatments, results indicate that LqFlbA plays a crucial role in controlling fungal growth, and both LqRax1 and LqRgsA are involved in overcoming the host chemical resistances and successful colonization.
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Affiliation(s)
| | | | | | - Hui Chen
- Correspondence: ; Tel.: +86-135-1911-6730
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Yaakoub H, Mina S, Calenda A, Bouchara JP, Papon N. Oxidative stress response pathways in fungi. Cell Mol Life Sci 2022; 79:333. [PMID: 35648225 PMCID: PMC11071803 DOI: 10.1007/s00018-022-04353-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/21/2022] [Accepted: 05/05/2022] [Indexed: 11/03/2022]
Abstract
Fungal response to any stress is intricate, specific, and multilayered, though it employs only a few evolutionarily conserved regulators. This comes with the assumption that one regulator operates more than one stress-specific response. Although the assumption holds true, the current understanding of molecular mechanisms that drive response specificity and adequacy remains rudimentary. Deciphering the response of fungi to oxidative stress may help fill those knowledge gaps since it is one of the most encountered stress types in any kind of fungal niche. Data have been accumulating on the roles of the HOG pathway and Yap1- and Skn7-related pathways in mounting distinct and robust responses in fungi upon exposure to oxidative stress. Herein, we review recent and most relevant studies reporting the contribution of each of these pathways in response to oxidative stress in pathogenic and opportunistic fungi after giving a paralleled overview in two divergent models, the budding and fission yeasts. With the concept of stress-specific response and the importance of reactive oxygen species in fungal development, we first present a preface on the expanding domain of redox biology and oxidative stress.
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Affiliation(s)
- Hajar Yaakoub
- Univ Angers, Univ Brest, IRF, SFR ICAT, 49000, Angers, France
| | - Sara Mina
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | | | | | - Nicolas Papon
- Univ Angers, Univ Brest, IRF, SFR ICAT, 49000, Angers, France.
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Regulator of G Protein Signaling Contributes to the Development and Aflatoxin Biosynthesis in Aspergillus flavus through the Regulation of Gα Activity. Appl Environ Microbiol 2022; 88:e0024422. [PMID: 35638847 PMCID: PMC9238415 DOI: 10.1128/aem.00244-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G-proteins play crucial roles in growth, asexual development, and pathogenicity of fungi. The regulator of G-protein signaling (RGS) proteins function as negative regulators of the G proteins to control the activities of GTPase in Gα subunits. In this study, we functionally characterized the six RGS proteins (i.e., RgsA, RgsB, RgsC, RgsD, RgsE, and FlbA) in the pathogenic fungus Aspergillus flavus. All the aforementioned RGS proteins were also found to be functionally different in conidiation, aflatoxin (AF) biosynthesis, and pathogenicity in A. flavus. Apart from FlbA, all other RGS proteins play a negative role in regulating both the synthesis of cyclic AMP (cAMP) and the activation of protein kinase A (PKA). Additionally, we also found that although RgsA and RgsE play a negative role in regulating the FadA-cAMP/PKA pathway, they function distinctly in aflatoxin biosynthesis. Similarly, RgsC is important for aflatoxin biosynthesis by negatively regulating the GanA-cAMP/PKA pathway. PkaA, which is the cAMP-dependent protein kinase catalytic subunit, also showed crucial influences on A. flavus phenotypes. Overall, our results demonstrated that RGS proteins play multiple roles in the development, pathogenicity, and AF biosynthesis in A. flavus through the regulation of Gα subunits and cAMP-PKA signals. IMPORTANCE RGS proteins, as crucial regulators of the G protein signaling pathway, are widely distributed in fungi, while little is known about their roles in Aspergillus flavus development and aflatoxin. In this study, we identified six RGS proteins in A. flavus and revealed that these proteins have important functions in the regulation of conidia, sclerotia, and aflatoxin formation. Our findings provide evidence that the RGS proteins function upstream of cAMP-PKA signaling by interacting with the Gα subunits (GanA and FadA). This study provides valuable information for controlling the contamination of A. flavus and mycotoxins produced by this fungus in pre- and postharvest of agricultural crops.
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Yaakoub H, Sanchez NS, Ongay-Larios L, Courdavault V, Calenda A, Bouchara JP, Coria R, Papon N. The high osmolarity glycerol (HOG) pathway in fungi †. Crit Rev Microbiol 2021; 48:657-695. [PMID: 34893006 DOI: 10.1080/1040841x.2021.2011834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
While fungi are widely occupying nature, many species are responsible for devastating mycosis in humans. Such niche diversity explains how quick fungal adaptation is necessary to endow the capacity of withstanding fluctuating environments and to cope with host-imposed conditions. Among all the molecular mechanisms evolved by fungi, the most studied one is the activation of the phosphorelay signalling pathways, of which the high osmolarity glycerol (HOG) pathway constitutes one of the key molecular apparatus underpinning fungal adaptation and virulence. In this review, we summarize the seminal knowledge of the HOG pathway with its more recent developments. We specifically described the HOG-mediated stress adaptation, with a particular focus on osmotic and oxidative stress, and point out some lags in our understanding of its involvement in the virulence of pathogenic species including, the medically important fungi Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus, compared to the model yeast Saccharomyces cerevisiae. Finally, we also highlighted some possible applications of the HOG pathway modifications to improve the fungal-based production of natural products in the industry.
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Affiliation(s)
- Hajar Yaakoub
- Univ Angers, Univ Brest, GEIHP, SFR ICAT, Angers, France
| | - Norma Silvia Sanchez
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City, Mexico
| | - Laura Ongay-Larios
- Unidad de Biología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Vincent Courdavault
- EA2106 "Biomolécules et Biotechnologies Végétales", Université de Tours, Tours, France
| | | | | | - Roberto Coria
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City, Mexico
| | - Nicolas Papon
- Univ Angers, Univ Brest, GEIHP, SFR ICAT, Angers, France
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Fang X, Dong F, Wang S, Wang G, Wu D, Lee YW, Ramzy Mohamed S, Goda AAK, Xu J, Shi J, Liu X. The FaFlbA mutant of Fusarium asiaticum is significantly increased in nivalenol production. J Appl Microbiol 2021; 132:3028-3037. [PMID: 34865297 DOI: 10.1111/jam.15404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/01/2021] [Accepted: 12/02/2021] [Indexed: 01/12/2023]
Abstract
AIMS Cereals contaminated with type B trichothecene nivalenol (NIV) and its acetylated derivative 4-acetyl-nivalenol (4-AcNIV) are a global mycotoxicological problem threatening the health of humans and livestock. Toxicological studies, quantitative determinations and screening for biodegrading micro-organisms require massive amounts of pure toxins. However, the low yield from fungal cultures and high prices of NIV and 4-AcNIV limit research progress in these areas. This work aimed to select Fusarium asiaticum mutant strains with enhanced production of NIV and 4-AcNIV. METHODS AND RESULTS A total of 62 NIV-producing F. asiaticum strains were isolated and compared regarding their ability to produce NIV. Strain RR108 had the highest yield of NIV among 62 field isolates surveyed and was then genetically modified for higher production. Targeted deletion of the FaFlbA gene, encoding a regulator of G protein signalling protein, resulted in a significant increase in NIV and 4-AcNIV production in the FaFlbA deletion mutant ΔFaFlbA. The expression of three TRI genes involved in the trichothecene biosynthetic pathway was upregulated in ΔFaFlbA. ΔFaFlbA produced the highest amount of NIV and 4-AcNIV when cultured in brown long-grain rice for 21 days, and the yields were 2.07 and 2.84 g kg-1 , respectively. The mutant showed reduced fitness, including reduced conidiation, loss of perithecial development and decreased virulence on wheat heads, which makes it biologically safe for large-scale preparation and purification of NIV and 4-AcNIV. CONCLUSIONS The F. asiaticum mutant strain ΔFaFlbA presented improved production of NIV and 4-AcNIV with reduced fitness and virulence in plants. SIGNIFICANCE AND IMPACT OF THE STUDY Targeted deletion of the FaFlbA gene resulted in increased NIV and 4-AcNIV production. Our results provide a practical approach using genetic modification for large-scale mycotoxin production.
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Affiliation(s)
- Xin Fang
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Fei Dong
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
| | - Shuang Wang
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Gang Wang
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Deliang Wu
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
| | - Yin-Won Lee
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Sherif Ramzy Mohamed
- Food Toxicology and Contaminants Department, National Research Centre, Giza, Egypt, Giza, Egypt
| | - Amira Abdel-Karim Goda
- Food Toxicology and Contaminants Department, National Research Centre, Giza, Egypt, Giza, Egypt
| | - Jianhong Xu
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Jianrong Shi
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Xin Liu
- Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology/Key Laboratory for Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture and Rural Affairs/Key Laboratory for Agro-product Safety Risk Evaluation (Nanjing), Ministry of Agriculture and Rural Affairs/Collaborative Innovation Center for Modern Grain Circulation and Safety/Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China.,School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, China
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Heterotrimeric G-protein signalers and RGSs in Aspergillus fumigatus. Pathogens 2020; 9:pathogens9110902. [PMID: 33126739 PMCID: PMC7693823 DOI: 10.3390/pathogens9110902] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 12/18/2022] Open
Abstract
The heterotrimeric G-protein (G-protein) signaling pathway is one of the most important signaling pathways that transmit external signals into the inside of the cell, triggering appropriate biological responses. The external signals are sensed by various G-protein-coupled receptors (GPCRs) and transmitted into G-proteins consisting of the α, β, and γ subunits. Regulators of G-protein signaling (RGSs) are the key controllers of G-protein signaling pathways. GPCRs, G-proteins, and RGSs are the primary upstream components of the G-protein signaling pathway, and they are highly conserved in most filamentous fungi, playing diverse roles in biological processes. Recent studies characterized the G-protein signaling components in the opportunistic pathogenic fungus Aspergillus fumigatus. In this review, we have summarized the characteristics and functions of GPCRs, G-proteins, and RGSs, and their regulatory roles in governing fungal growth, asexual development, germination, stress tolerance, and virulence in A. fumigatus.
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Choi YH, Lee MW, Igbalajobi OA, Yu JH, Shin KS. Transcriptomic and Functional Studies of the RGS Protein Rax1 in Aspergillus fumigatus. Pathogens 2019; 9:pathogens9010036. [PMID: 31906167 PMCID: PMC7168642 DOI: 10.3390/pathogens9010036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 12/26/2019] [Accepted: 12/30/2019] [Indexed: 12/24/2022] Open
Abstract
In the comparative transcriptomic studies of wild type (WT) and rax1 null mutant strains, we obtained an average of 22,222,727 reads of 101 bp per sample and found that 183 genes showed greater than 2.0-fold differential expression, where 92 and 91 genes were up-and down-regulated in Δrax1 compared to WT, respectively. In accordance with the significantly reduced levels of gliM and casB transcripts in the absence of rax1, the Δrax1 mutant exhibited increased sensitivity to exogenous gliotoxin (GT) without affecting levels of GT production. Moreover, Δrax1 resulted in significantly restricted colony growth and reduced viability under endoplasmic reticulum stress condition. In summary, Rax1 positively affects expression of gliM and metacaspase genes.
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Affiliation(s)
- Yong-Ho Choi
- Department of Microbiology, Graduate School, Daejeon University, Daejeon 34520, Korea;
| | - Min-Woo Lee
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Chungcheongnam-do 31151, Korea;
| | - Olumuyiwa Ayokunle Igbalajobi
- Department of Microbiology, Institute for Applied Biosciences, Karlsruhe Institute of Technology, Fritz-Haber Weg 4, D-76131 Karlsruhe, Germany;
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
- Correspondence: (J.-H.Y.); (K.-S.S.)
| | - Kwang-Soo Shin
- Department of Microbiology, Graduate School, Daejeon University, Daejeon 34520, Korea;
- Correspondence: (J.-H.Y.); (K.-S.S.)
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Lwin HP, Choi YH, Lee MW, Yu JH, Shin KS. RgsA Attenuates the PKA Signaling, Stress Response, and Virulence in the Human Opportunistic Pathogen Aspergillus fumigatus. Int J Mol Sci 2019; 20:ijms20225628. [PMID: 31717953 PMCID: PMC6888639 DOI: 10.3390/ijms20225628] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/05/2019] [Accepted: 11/07/2019] [Indexed: 12/14/2022] Open
Abstract
The regulator of G-protein signaling (RGS) proteins play an important role in upstream control of heterotrimeric G-protein signaling pathways. In the genome of the human opportunistic pathogenic fungus Aspergillus fumigatus, six RGS protein-encoding genes are present. To characterize the rgsA gene predicted to encode a protein with an RGS domain, we generated an rgsA null mutant and observed the phenotypes of the mutant. The deletion (Δ) of rgsA resulted in increased radial growth and enhanced asexual sporulation in both solid and liquid culture conditions. Accordingly, transcripts levels of the key asexual developmental regulators abaA, brlA, and wetA are elevated in the ΔrgsA mutant. Moreover, ΔrgsA resulted in elevated spore germination rates in the absence of a carbon source. The activity of cAMP-dependent protein kinase A (PKA) and mRNA levels of genes encoding PKA signaling elements are elevated by ΔrgsA. In addition, mRNA levels of genes associated with stress-response signaling increased with the lack of rgsA, and the ΔrgsA spores showed enhanced tolerance against oxidative stressors. Comparative transcriptomic analyses revealed that the ΔrgsA mutant showed higher mRNA levels of gliotoxin (GT) biosynthetic genes. Accordingly, the rgsA null mutant exhibited increased production of GT and elevated virulence in the mouse. Conversely, the majority of genes encoding glucan degrading enzymes were down-regulated by ΔrgsA, and endoglucanase activities were reduced. In summary, RgsA plays multiple roles, governing growth, development, stress responses, virulence, and external polymer degradation-likely by attenuating PKA signaling.
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Affiliation(s)
- Hnin Phyu Lwin
- Department of Microbiology, Graduate School, Daejeon University, Daejeon 34520, Korea; (H.P.L.); (Y.-H.C.)
| | - Yong-Ho Choi
- Department of Microbiology, Graduate School, Daejeon University, Daejeon 34520, Korea; (H.P.L.); (Y.-H.C.)
| | - Min-Woo Lee
- Soonchunhyang Institute of Medi-bio Science, Soonchunhyang University, Chungcheongnam-do 31151, Korea;
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
- Correspondence: (J.-H.Y.); (K.-S.S.); Tel.: +1-608-262-4696 (J.-H.Y.); +82-42-280-2439 (K.-S.S.); Fax: +1-608-262-2976 (J.-H.Y.); +82-42-280-2608 (K.-S.S.)
| | - Kwang-Soo Shin
- Department of Microbiology, Graduate School, Daejeon University, Daejeon 34520, Korea; (H.P.L.); (Y.-H.C.)
- Correspondence: (J.-H.Y.); (K.-S.S.); Tel.: +1-608-262-4696 (J.-H.Y.); +82-42-280-2439 (K.-S.S.); Fax: +1-608-262-2976 (J.-H.Y.); +82-42-280-2608 (K.-S.S.)
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10
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RgsD negatively controls development, toxigenesis, stress response, and virulence in Aspergillus fumigatus. Sci Rep 2019; 9:811. [PMID: 30692551 PMCID: PMC6349852 DOI: 10.1038/s41598-018-37124-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 11/28/2018] [Indexed: 12/19/2022] Open
Abstract
The regulator of G protein signaling (RGS) domain proteins generally attenuate heterotrimeric G protein signaling, thereby fine-tune the duration and strength of signal transduction. In this study, we characterize the functions of RgsD, one of the six RGS domain proteins present in the human pathogenic fungus Aspergillus fumigatus. The deletion (Δ) of rgsD results in enhanced asexual sporulation coupled with increased mRNA levels of key developmental activators. Moreover, ΔrgsD leads to increased spore tolerance to UV and oxidative stress, which might be associated with the enhanced expression of melanin biosynthetic genes and increased amount of melanin. Yeast two-hybrid assays reveal that RgsD can interact with the three Gα proteins GpaB, GanA, and GpaA, showing the highest interaction potential with GpaB. Importantly, the ΔrgsD mutant shows elevated expression of genes in the cAMP-dependent protein kinase A (PKA) pathway and PKA catalytic activity. The ΔrgsD mutant also display increased gliotoxin production and elevated virulence toward Galleria mellonella wax moth larvae. Transcriptomic analyses using RNA-seq reveal the expression changes associated with the diverse phenotypic outcomes caused by ΔrgsD. Collectively, we conclude that RgsD attenuates cAMP-PKA signaling pathway and negatively regulates asexual development, toxigenesis, melanin production, and virulence in A. fumigatus.
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Kim Y, Heo IB, Yu JH, Shin KS. Characteristics of a Regulator of G-Protein Signaling (RGS) rgsC in Aspergillus fumigatus. Front Microbiol 2017; 8:2058. [PMID: 29109714 PMCID: PMC5660106 DOI: 10.3389/fmicb.2017.02058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/06/2017] [Indexed: 12/12/2022] Open
Abstract
The regulator of G-protein signaling (RGS) proteins have a conserved RGS domain that facilitates the intrinsic GTPase activity of an activated Gα subunit of heterotrimeric G protein, thereby attenuating signal transduction. Among six predicted RGS proteins in the opportunistic human pathogenic fungus Aspergillus fumigatus, only three (FlbA, GprK, and Rax1) have been studied. The unexplored RgsC composed of the Phox-associated (PXA), RGS, Phox homology (PX), and Nexin_C superfamily domains is highly conserved in many ascomycete fungi, suggesting a crucial role of RgsC in fungal biology. To address this, we have investigated functions of the rgsC gene. The deletion (Δ) of rgsC causes impaired vegetative growth and asexual development coupled with reduced expression of key developmental regulators. Moreover, ΔrgsC results in accelerated and elevated conidial germination regardless of the presence or absence of an external carbon source. Furthermore, ΔrgsC causes reduced conidial tolerance to oxidative stress. In addition, activities and expression of catalases and superoxide dismutases (SODs) are severely decreased in the ΔrgsC mutant. The deletion of rgsC results in a slight reduction in conidial tolerance to cell wall damaging agents, yet significantly lowered mRNA levels of cell wall integrity/biogenesis transcription factors, indicating that RgsC may function in proper activation of cell wall stress response. The ΔrgsC mutant exhibits defective gliotoxin (GT) production and decreased virulence in the wax moth larvae, Galleria mellonella. Transcriptomic studies reveal that a majority of transporters is down-regulated by ΔrgsC and growth of the ΔrgsC mutant is reduced on inorganic and simple nitrogen medium, suggesting that RgsC may function in external nitrogen source sensing and/or transport. In summary, RgsC is necessary for proper growth, development, stress response, GT production, and external nutrients sensing.
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Affiliation(s)
- Young Kim
- Department of Biological Science, Daejeon University, Daejeon, South Korea
| | - In-Beom Heo
- Department of Biological Science, Daejeon University, Daejeon, South Korea
| | - Jae-Hyuk Yu
- Departments of Bacteriology and Genetics, University of Wisconsin-Madison, Madison, WI, United States
| | - Kwang-Soo Shin
- Department of Biological Science, Daejeon University, Daejeon, South Korea
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