1
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Zhang L, Sun K, Li Y, Ma T, Zhang Y, Yin Y, Zhang S, Shao W. The Importin FgPse1 Is Required for Vegetative Development, Virulence, and Deoxynivalenol Production by Interacting with the Nuclear Polyadenylated RNA-Binding Protein FgNab2 in Fusarium graminearum. PHYTOPATHOLOGY 2022; 112:1072-1080. [PMID: 34784736 DOI: 10.1094/phyto-08-21-0357-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Karyopherins are involved in transport through nuclear pore complexes. Karyopherins are necessary for nuclear import and export pathways and bind to their cargos. Polyadenylation of messenger RNA (mRNA) is necessary for various biological processes, regulating gene expression in eukaryotes. Until now, the association of karyopherin with mRNA polyadenylation has been less understood in plant pathogenic fungi. In our study, we focused on the biological functions of the karyopherin FgPse1 in Fusarium graminearum. The results showed that FgPse1 is involved in mycelial growth, asexual reproduction, virulence, and deoxynivalenol (DON) production. Co-immunoprecipitation and bimolecular fluorescence complementation showed that FgPse1 interacts with the nuclear polyadenylated RNA-binding protein FgNab2. Moreover, a fluorescence localization assay indicated that FgPse1 is necessary for the nuclear import of FgNab2. The nuclear import of FgNab2 regulates the expression of FgTri4, FgTri5, and FgTri6, which are essential for DON production. Thus, ΔFgPse1 and ΔFgNab2 showed consistent defects in DON production. In summary, our data indicated that FgPse1 is necessary for mycelial growth, virulence, and DON production, interacting with FgNab2 in F. graminearum. These results contribute to our understanding of the functions of importins in phytopathogenic fungi.
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Affiliation(s)
- Lixin Zhang
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Kewei Sun
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yiqing Li
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Tianling Ma
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yu Zhang
- Department of Crop Protection, Zhejiang Agriculture and Forest University, Hangzhou 311300, China
| | - Yanni Yin
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Shuai Zhang
- National Agro-technology Extension and Service Center, Beijing 100125, China
| | - Wenyong Shao
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
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Zhang S, Lin C, Zhou T, Zhang LH, Deng YZ. Karyopherin MoKap119-mediated nuclear import of cyclin-dependent kinase regulator MoCks1 is essential for Magnaporthe oryzae pathogenicity. Cell Microbiol 2019; 22:e13114. [PMID: 31487436 DOI: 10.1111/cmi.13114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 08/21/2019] [Accepted: 09/02/2019] [Indexed: 12/29/2022]
Abstract
Nuclear import of proteins relies on nuclear import receptors called importins/karyopherins (Kaps), whose functions were reported in yeasts, fungi, plants, and animal cells, including cell cycle control, morphogenesis, stress sensing/response, and also fungal pathogenecity. However, limited is known about the physiological function and regulatory mechanism of protein import in the rice-blast fungus Magnaporthe oryzae. Here, we identified an ortholog of β-importin in M. oryzae encoded by an ortholog of KAP119 gene. Functional characterisation of this gene via reverse genetics revealed that it is required for vegetative growth, conidiation, melanin pigmentation, and pathogenicity of M. oryzae. The mokap119Δ mutant was also defective in formation of appressorium-like structure from hyphal tips. By affinity assay and liquid chromatography-tandem mass spectrometry, we identified potential MoKap119-interacting proteins and further verified that MoKap119 interacts with the cyclin-dependent kinase subunit MoCks1 and mediates its nuclear import. Transcriptional profiling indicated that MoKap119 may regulate transcription of infection-related genes via MoCks1 regulation of MoSom1. Overall, our findings provide a novel insight into the regulatory mechanism of M. oryzae pathogenesis likely by MoKap119-mediated nuclear import of the cyclin-dependent kinase subunit MoCks1.
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Affiliation(s)
- Shulin Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.,Integrative Microbiology Research Centre/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Chaoxiang Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.,Integrative Microbiology Research Centre/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Tian Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.,Integrative Microbiology Research Centre/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Lian-Hui Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.,Integrative Microbiology Research Centre/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
| | - Yi Zhen Deng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.,Integrative Microbiology Research Centre/Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, China
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3
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UrdA Controls Secondary Metabolite Production and the Balance between Asexual and Sexual Development in Aspergillus nidulans. Genes (Basel) 2018; 9:genes9120570. [PMID: 30477161 PMCID: PMC6316066 DOI: 10.3390/genes9120570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/15/2018] [Accepted: 11/19/2018] [Indexed: 01/07/2023] Open
Abstract
The genus Aspergillus includes important plant pathogens, opportunistic human pathogens and mycotoxigenic fungi. In these organisms, secondary metabolism and morphogenesis are subject to a complex genetic regulation. Here we functionally characterized urdA, a gene encoding a putative helix-loop-helix (HLH)-type regulator in the model fungus Aspergillus nidulans. urdA governs asexual and sexual development in strains with a wild-type veA background; absence of urdA resulted in severe morphological alterations, with a significant reduction of conidial production and an increase in cleistothecial formation, even in the presence of light, a repressor of sex. The positive effect of urdA on conidiation is mediated by the central developmental pathway (CDP). However, brlA overexpression was not sufficient to restore wild-type conidiation in the ΔurdA strain. Heterologous complementation of ΔurdA with the putative Aspergillus flavus urdA homolog also failed to rescue conidiation wild-type levels, indicating that both genes perform different functions, probably reflected by key sequence divergence. UrdA also represses sterigmatocystin (ST) toxin production in the presence of light by affecting the expression of aflR, the activator of the ST gene cluster. Furthermore, UrdA regulates the production of several unknown secondary metabolites, revealing a broader regulatory scope. Interestingly, UrdA affects the abundance and distribution of the VeA protein in hyphae, and our genetics studies indicated that veA appears epistatic to urdA regarding ST production. However, the distinct fluffy phenotype of the ΔurdAΔveA double mutant suggests that both regulators conduct independent developmental roles. Overall, these results suggest that UrdA plays a pivotal role in the coordination of development and secondary metabolism in A. nidulans.
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Yan Y, Yuan Q, Tang J, Huang J, Hsiang T, Wei Y, Zheng L. Colletotrichum higginsianum as a Model for Understanding Host⁻Pathogen Interactions: A Review. Int J Mol Sci 2018; 19:E2142. [PMID: 30041456 PMCID: PMC6073530 DOI: 10.3390/ijms19072142] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/18/2018] [Accepted: 07/18/2018] [Indexed: 11/16/2022] Open
Abstract
Colletotrichum higginsianum is a hemibiotrophic ascomycetous fungus that causes economically important anthracnose diseases on numerous monocot and dicot crops worldwide. As a model pathosystem, the Colletotrichum⁻Arabidopsis interaction has the significant advantage that both organisms can be manipulated genetically. The goal of this review is to provide an overview of the system and to point out recent significant studies that update our understanding of the pathogenesis of C. higginsianum and resistance mechanisms of Arabidopsis against this hemibiotrophic fungus. The genome sequence of C. higginsianum has provided insights into how genome structure and pathogen genetic variability has been shaped by transposable elements, and allows systematic approaches to longstanding areas of investigation, including infection structure differentiation and fungal⁻plant interactions. The Arabidopsis-Colletotrichum pathosystem provides an integrated system, with extensive information on the host plant and availability of genomes for both partners, to illustrate many of the important concepts governing fungal⁻plant interactions, and to serve as an excellent starting point for broad perspectives into issues in plant pathology.
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Affiliation(s)
- Yaqin Yan
- The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
| | - Qinfeng Yuan
- The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jintian Tang
- The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
| | - Junbin Huang
- The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
| | - Tom Hsiang
- School of Environmental Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Yangdou Wei
- Department of Biology, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.
| | - Lu Zheng
- The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China.
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Feng X, Ramamoorthy V, Pandit SS, Prieto A, Espeso EA, Calvo AM. cpsA regulates mycotoxin production, morphogenesis and cell wall biosynthesis in the fungus Aspergillus nidulans. Mol Microbiol 2017; 105:1-24. [PMID: 28370587 PMCID: PMC5506848 DOI: 10.1111/mmi.13682] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/21/2017] [Accepted: 03/26/2017] [Indexed: 01/07/2023]
Abstract
The model fungus Aspergillus nidulans synthesizes numerous secondary metabolites, including sterigmatocystin (ST). The production of this toxin is positively controlled by the global regulator veA. In the absence of veA (ΔveA), ST biosynthesis is blocked. Previously, we performed random mutagenesis in a ΔveA strain and identified revertant mutants able to synthesize ST, among them RM1. Complementation of RM1 with a genomic library revealed that the mutation occurred in a gene designated as cpsA. While in the ΔveA genetic background cpsA deletion restores ST production, in a veA wild-type background absence of cpsA reduces and delays ST biosynthesis decreasing the expression of ST genes. Furthermore, cpsA is also necessary for the production of other secondary metabolites, including penicillin, affecting the expression of PN genes. In addition, cpsA is necessary for normal asexual and sexual development. Chemical and microscopy analyses revealed that CpsA is found in cytoplasmic vesicles and it is required for normal cell wall composition and integrity, affecting adhesion capacity and oxidative stress sensitivity. The conservation of cpsA in Ascomycetes suggests that cpsA homologs might have similar roles in other fungal species.
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Affiliation(s)
- Xuehuan Feng
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
| | - Vellaisamy Ramamoorthy
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA,Dept. of Plant Pathology Agricultural College and Research Institute Killikulam, Vallanadu - 628 252 Thoothukudi District Tamil Nadu, India
| | - Sandesh S. Pandit
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
| | - Alicia Prieto
- Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | | | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA,Author to whom correspondence should be addressed [telephone: (815) 753-0451]; fax (815) 753-0461; ]
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6
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rtfA, a putative RNA-Pol II transcription elongation factor gene, is necessary for normal morphological and chemical development in Aspergillus flavus. Appl Microbiol Biotechnol 2016; 100:5029-41. [PMID: 27020290 DOI: 10.1007/s00253-016-7418-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/22/2016] [Accepted: 02/24/2016] [Indexed: 01/05/2023]
Abstract
The filamentous fungus Aspergillus flavus is an agriculturally important opportunistic plant pathogen that produces potent carcinogenic compounds called aflatoxins. We identified the A. flavus rtfA gene, the ortholog of rtf1 in Saccharomyces cerevisiae and rtfA in Aspergillus nidulans. Interestingly, rtfA has multiple cellular roles in this mycotoxin-producing fungus. In this study, we show that rtfA regulates conidiation. The rtfA deletion mutant presented smaller conidiophores with significantly reduced conidial production compared to the wild-type strain. The absence of rtfA also resulted in a significant decrease or lack of sclerotial production under conditions that allowed abundant production of these resistance structures in the wild type. Importantly, the deletion of rtfA notably reduced the production of aflatoxin B1, indicating that rtfA is a regulator of mycotoxin biosynthesis in A. flavus. In addition, the deletion rtfA also altered the production of several unknown secondary metabolites indicating a broader regulatory scope. Furthermore, our study revealed that rtfA controls the expression of the global regulators veA and laeA, which further influence morphogenesis and secondary metabolism in A. flavus.
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Herrero-Garcia E, Perez-de-Nanclares-Arregi E, Cortese MS, Markina-Iñarrairaegui A, Oiartzabal-Arano E, Etxebeste O, Ugalde U, Espeso EA. Tip-to-nucleus migration dynamics of the asexual development regulator FlbB in vegetative cells. Mol Microbiol 2015; 98:607-24. [PMID: 26256571 DOI: 10.1111/mmi.13156] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2015] [Indexed: 01/24/2023]
Abstract
In Aspergillus nidulans, asexual differentiation requires the presence of the transcription factor FlbB at the cell tip and apical nuclei. Understanding the relationship between these two pools is crucial for elucidating the biochemical processes mediating conidia production. Tip-to-nucleus communication was demonstrated by photo-convertible FlbB::Dendra2 visualization. Tip localization of FlbB depends on Cys382 in the C-terminus and the bZIP DNA-binding domain in the N-terminus. FlbE, a critical FlbB interactor, binds the bZIP domain. Furthermore, the absence of FlbE results in loss of tip localization but not nuclear accumulation. flbE deletion also abrogates transcriptional activity indicating that FlbB gains transcriptional competence from interactions with FlbE at the tip. Finally, a bipartite nuclear localization signal is required for nuclear localization of FlbB. Those motifs of FlbB may play various roles in the sequence of events necessary for the distribution and activation of this transcriptionally active developmental factor. The tip accumulation, FlbE-dependent activation, transport and nuclear import sketch out a process of relaying an environmentally triggered signal from the tip to the nuclei. As the first known instance of transcription factor-mediated tip-to-nucleus communication in filamentous fungi, this provides a general framework for analyses focused on elucidating the set of molecular mechanisms coupling apical signals to transcriptional events.
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Affiliation(s)
- Erika Herrero-Garcia
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Elixabet Perez-de-Nanclares-Arregi
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Marc S Cortese
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Ane Markina-Iñarrairaegui
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Elixabet Oiartzabal-Arano
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Oier Etxebeste
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Unai Ugalde
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain
| | - Eduardo A Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
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8
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Yang X, Ding F, Zhang L, Sheng Y, Zheng X, Wang Y. The importin α subunit PsIMPA1 mediates the oxidative stress response and is required for the pathogenicity of Phytophthora sojae. Fungal Genet Biol 2015; 82:108-15. [DOI: 10.1016/j.fgb.2015.04.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/28/2015] [Accepted: 04/29/2015] [Indexed: 11/24/2022]
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Ghassemi S, Lichius A, Bidard F, Lemoine S, Rossignol MN, Herold S, Seidl-Seiboth V, Seiboth B, Espeso EA, Margeot A, Kubicek CP. The ß-importin KAP8 (Pse1/Kap121) is required for nuclear import of the cellulase transcriptional regulator XYR1, asexual sporulation and stress resistance in Trichoderma reesei. Mol Microbiol 2015; 96:405-18. [PMID: 25626518 PMCID: PMC4390390 DOI: 10.1111/mmi.12944] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 11/26/2022]
Abstract
The ascomycete Trichoderma reesei is an industrial producer of cellulolytic and hemicellulolytic enzymes, and serves as a prime model for their genetic regulation. Most of its (hemi-)cellulolytic enzymes are obligatorily dependent on the transcriptional activator XYR1. Here, we investigated the nucleo-cytoplasmic shuttling mechanism that transports XYR1 across the nuclear pore complex. We identified 14 karyopherins in T. reesei, of which eight were predicted to be involved in nuclear import, and produced single gene-deletion mutants of all. We found KAP8, an ortholog of Aspergillus nidulans KapI, and Saccharomyces cerevisiae Kap121/Pse1, to be essential for nuclear recruitment of GFP-XYR1 and cellulase gene expression. Transformation with the native gene rescued this effect. Transcriptomic analyses of Δkap8 revealed that under cellulase-inducing conditions 42 CAZymes, including all cellulases and hemicellulases known to be under XYR1 control, were significantly down-regulated. Δkap8 strains were capable of forming fertile fruiting bodies but exhibited strongly reduced conidiation both in light and darkness, and showed enhanced sensitivity towards abiotic stress, including high osmotic pressure, low pH and high temperature. Together, these data underscore the significance of nuclear import of XYR1 in cellulase and hemicellulase gene regulation in T. reesei, and identify KAP8 as the major karyopherin required for this process.
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Affiliation(s)
- Sara Ghassemi
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
| | - Alexander Lichius
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
| | - Fréderique Bidard
- IFP Energies nouvelles1-4 avenue de Bois-Préau, 92852, Rueil-Malmaison, France
| | - Sophie Lemoine
- Ecole Normale Supérieure, Institut de Biologie de l'ENSIBENS, Plateforme Génomique, Paris, F-75005, France
| | - Marie-Noëlle Rossignol
- Ecole Normale Supérieure, Institut de Biologie de l'ENSIBENS, Plateforme Génomique, Paris, F-75005, France
| | - Silvia Herold
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
| | - Verena Seidl-Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
| | - Bernhard Seiboth
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
- ACIB GmbH, c/o Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
| | - Eduardo A Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Antoine Margeot
- IFP Energies nouvelles1-4 avenue de Bois-Préau, 92852, Rueil-Malmaison, France
| | - Christian P Kubicek
- Research Division Biotechnology and Microbiology, Institute of Chemical EngineeringTU Wien, Vienna, 1060, Austria
- *For correspondence. E-mail ; Tel. (+ 1) 43 1 58801 166085; Fax (+ 1) 43 1 58801 17299
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Calvo AM, Cary JW. Association of fungal secondary metabolism and sclerotial biology. Front Microbiol 2015; 6:62. [PMID: 25762985 PMCID: PMC4329819 DOI: 10.3389/fmicb.2015.00062] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/18/2015] [Indexed: 11/13/2022] Open
Abstract
Fungal secondary metabolism and morphological development have been shown to be intimately associated at the genetic level. Much of the literature has focused on the co-regulation of secondary metabolite production (e.g., sterigmatocystin and aflatoxin in Aspergillus nidulans and Aspergillus flavus, respectively) with conidiation or formation of sexual fruiting bodies. However, many of these genetic links also control sclerotial production. Sclerotia are resistant structures produced by a number of fungal genera. They also represent the principal source of primary inoculum for some phytopathogenic fungi. In nature, higher plants often concentrate secondary metabolites in reproductive structures as a means of defense against herbivores and insects. By analogy, fungi also sequester a number of secondary metabolites in sclerotia that act as a chemical defense system against fungivorous predators. These include antiinsectant compounds such as tetramic acids, indole diterpenoids, pyridones, and diketopiperazines. This chapter will focus on the molecular mechanisms governing production of secondary metabolites and the role they play in sclerotial development and fungal ecology, with particular emphasis on Aspergillus species. The global regulatory proteins VeA and LaeA, components of the velvet nuclear protein complex, serve as virulence factors and control both development and secondary metabolite production in many Aspergillus species. We will discuss a number of VeA- and LaeA-regulated secondary metabolic gene clusters in A. flavus that are postulated to be involved in sclerotial morphogenesis and chemical defense. The presence of multiple regulatory factors that control secondary metabolism and sclerotial formation suggests that fungi have evolved these complex regulatory mechanisms as a means to rapidly adapt chemical responses to protect sclerotia from predators, competitors and other environmental stressors.
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Affiliation(s)
- Ana M Calvo
- Department of Biological Sciences, Northern Illinois University DeKalb, IL, USA
| | - Jeffrey W Cary
- Southern Regional Research Center, United States Department of Agriculture - Agricultural Research Service New Orleans, LA, USA
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11
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Zhang F, Zhong H, Han X, Guo Z, Yang W, Liu Y, Yang K, Zhuang Z, Wang S. Proteomic profile of Aspergillus flavus in response to water activity. Fungal Biol 2014; 119:114-24. [PMID: 25749363 DOI: 10.1016/j.funbio.2014.11.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 11/21/2014] [Accepted: 11/24/2014] [Indexed: 12/12/2022]
Abstract
Aspergillus flavus, a common contaminant of crops and stored grains, can produce aflatoxins that are harmful to humans and other animals. Water activity (aw) is one of the key factors influencing both fungal growth and mycotoxin production. In this study, we used the isobaric tagging for relative and absolute quantitation (iTRAQ) technique to investigate the effect of aw on the proteomic profile of A. flavus. A total of 3566 proteins were identified, of which 837 were differentially expressed in response to variations in aw. Among these 837 proteins, 403 were over-expressed at 0.99 aw, whereas 434 proteins were over-expressed at 0.93 aw. According to Gene Ontology (GO) analysis, the secretion of extracellular hydrolases increased as aw was raised, suggesting that extracellular hydrolases may play a critical role in induction of aflatoxin biosynthesis. On the basis of Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) categorizations, we identified an exportin protein, KapK, that may down-regulate aflatoxin biosynthesis by changing the location of NirA. Finally, we considered the role of two osmotic stress-related proteins (Sln1 and Glo1) in the Hog1 pathway and investigated the expression patterns of proteins related to aflatoxin biosynthesis. The data uncovered in this study are critical for understanding the effect of water stress on toxin production and for the development of strategies to control toxin contamination of agricultural products.
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Affiliation(s)
- Feng Zhang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hong Zhong
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiaoyun Han
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Zhenni Guo
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Weiqiang Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yongfeng Liu
- Shenzhen Key Laboratory of Bioenergy, BGI-Shenzhen, Shenzhen 518083, China
| | - Kunlong Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Zhenhong Zhuang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of the Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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12
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Duran RM, Gregersen S, Smith TD, Bhetariya PJ, Cary JW, Harris-Coward PY, Mattison CP, Grimm C, Calvo AM. The role of Aspergillus flavus veA in the production of extracellular proteins during growth on starch substrates. Appl Microbiol Biotechnol 2014; 98:5081-94. [DOI: 10.1007/s00253-014-5598-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/03/2014] [Accepted: 02/04/2014] [Indexed: 01/21/2023]
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13
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Multiple nuclear localization signals mediate nuclear localization of the GATA transcription factor AreA. EUKARYOTIC CELL 2014; 13:527-38. [PMID: 24562911 DOI: 10.1128/ec.00040-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Aspergillus nidulans GATA transcription factor AreA activates transcription of nitrogen metabolic genes in response to nitrogen limitation and is known to accumulate in the nucleus during nitrogen starvation. Sequence analysis of AreA revealed multiple nuclear localization signals (NLSs), five putative classical NLSs conserved in fungal AreA orthologs but not in the Saccharomyces cerevisiae functional orthologs Gln3p and Gat1p, and one putative noncanonical RRX33RXR bipartite NLS within the DNA-binding domain. In order to identify the functional NLSs in AreA, we constructed areA mutants with mutations in individual putative NLSs or combinations of putative NLSs and strains expressing green fluorescent protein (GFP)-AreA NLS fusion genes. Deletion of all five classical NLSs individually or collectively did not affect utilization of nitrogen sources or AreA-dependent gene expression and did not prevent AreA nuclear localization. Mutation of the bipartite NLS conferred the inability to utilize alternative nitrogen sources and abolished AreA-dependent gene expression likely due to effects on DNA binding but did not prevent AreA nuclear localization. Mutation of all six NLSs simultaneously prevented AreA nuclear accumulation. The bipartite NLS alone strongly directed GFP to the nucleus, whereas the classical NLSs collaborated to direct GFP to the nucleus. Therefore, AreA contains multiple conserved NLSs, which show redundancy and together function to mediate nuclear import. The noncanonical bipartite NLS is conserved in GATA factors from Aspergillus, yeast, and mammals, indicating an ancient origin.
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14
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Dhingra S, Lind AL, Lin HC, Tang Y, Rokas A, Calvo AM. The fumagillin gene cluster, an example of hundreds of genes under veA control in Aspergillus fumigatus. PLoS One 2013; 8:e77147. [PMID: 24116213 PMCID: PMC3792039 DOI: 10.1371/journal.pone.0077147] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 08/25/2013] [Indexed: 01/24/2023] Open
Abstract
Aspergillus fumigatus is the causative agent of invasive aspergillosis, leading to infection-related mortality in immunocompromised patients. We previously showed that the conserved and unique-to-fungi veA gene affects different cell processes such as morphological development, gliotoxin biosynthesis and protease activity, suggesting a global regulatory effect on the genome of this medically relevant fungus. In this study, RNA sequencing analysis revealed that veA controls the expression of hundreds of genes in A. fumigatus, including those comprising more than a dozen known secondary metabolite gene clusters. Chemical analysis confirmed that veA controls the synthesis of other secondary metabolites in this organism in addition to gliotoxin. Among the secondary metabolite gene clusters regulated by veA is the elusive but recently identified gene cluster responsible for the biosynthesis of fumagillin, a meroterpenoid known for its anti-angiogenic activity by binding to human methionine aminopeptidase 2. The fumagillin gene cluster contains a veA-dependent regulatory gene, fumR (Afu8g00420), encoding a putative C6 type transcription factor. Deletion of fumR results in silencing of the gene cluster and elimination of fumagillin biosynthesis. We found expression of fumR to also be dependent on laeA, a gene encoding another component of the fungal velvet complex. The results in this study argue that veA is a global regulator of secondary metabolism in A. fumigatus, and that veA may be a conduit via which chemical development is coupled to morphological development and other cellular processes.
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Affiliation(s)
- Sourabh Dhingra
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Abigail L. Lind
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Hsiao-Ching Lin
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California, United States of America
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Antonis Rokas
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
- * E-mail:
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15
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Ramamoorthy V, Dhingra S, Kincaid A, Shantappa S, Feng X, Calvo AM. The putative C2H2 transcription factor MtfA is a novel regulator of secondary metabolism and morphogenesis in Aspergillus nidulans. PLoS One 2013; 8:e74122. [PMID: 24066102 PMCID: PMC3774644 DOI: 10.1371/journal.pone.0074122] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Accepted: 07/28/2013] [Indexed: 01/07/2023] Open
Abstract
Secondary metabolism in the model fungus Aspergillus nidulans is controlled by the conserved global regulator VeA, which also governs morphological differentiation. Among the secondary metabolites regulated by VeA is the mycotoxin sterigmatocystin (ST). The presence of VeA is necessary for the biosynthesis of this carcinogenic compound. We identified a revertant mutant able to synthesize ST intermediates in the absence of VeA. The point mutation occurred at the coding region of a gene encoding a novel putative C2H2 zinc finger domain transcription factor that we denominated mtfA. The A. nidulans mtfA gene product localizes at nuclei independently of the illumination regime. Deletion of the mtfA gene restores mycotoxin biosynthesis in the absence of veA, but drastically reduced mycotoxin production when mtfA gene expression was altered, by deletion or overexpression, in A. nidulans strains with a veA wild-type allele. Our study revealed that mtfA regulates ST production by affecting the expression of the specific ST gene cluster activator aflR. Importantly, mtfA is also a regulator of other secondary metabolism gene clusters, such as genes responsible for the synthesis of terrequinone and penicillin. As in the case of ST, deletion or overexpression of mtfA was also detrimental for the expression of terrequinone genes. Deletion of mtfA also decreased the expression of the genes in the penicillin gene cluster, reducing penicillin production. However, in this case, over-expression of mtfA enhanced the transcription of penicillin genes, increasing penicillin production more than 5 fold with respect to the control. Importantly, in addition to its effect on secondary metabolism, mtfA also affects asexual and sexual development in A. nidulans. Deletion of mtfA results in a reduction of conidiation and sexual stage. We found mtfA putative orthologs conserved in other fungal species.
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Affiliation(s)
- Vellaisamy Ramamoorthy
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Sourabh Dhingra
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Alexander Kincaid
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Sourabha Shantappa
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Xuehuan Feng
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America,* E-mail:
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16
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Secondary metabolism and development is mediated by LlmF control of VeA subcellular localization in Aspergillus nidulans. PLoS Genet 2013; 9:e1003193. [PMID: 23341778 PMCID: PMC3547832 DOI: 10.1371/journal.pgen.1003193] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 11/09/2012] [Indexed: 12/22/2022] Open
Abstract
Secondary metabolism and development are linked in Aspergillus through the conserved regulatory velvet complex composed of VeA, VelB, and LaeA. The founding member of the velvet complex, VeA, shuttles between the cytoplasm and nucleus in response to alterations in light. Here we describe a new interaction partner of VeA identified through a reverse genetics screen looking for LaeA-like methyltransferases in Aspergillus nidulans. One of the putative LaeA-like methyltransferases identified, LlmF, is a negative regulator of sterigmatocystin production and sexual development. LlmF interacts directly with VeA and the repressive function of LlmF is mediated by influencing the localization of VeA, as over-expression of llmF decreases the nuclear to cytoplasmic ratio of VeA while deletion of llmF results in an increased nuclear accumulation of VeA. We show that the methyltransferase domain of LlmF is required for function; however, LlmF does not directly methylate VeA in vitro. This study identifies a new interaction partner for VeA and highlights the importance of cellular compartmentalization of VeA for regulation of development and secondary metabolism. In recent years there has been increased interest in bioactive small molecules produced by filamentous fungi. Members of the genus Aspergillus are prolific producers of natural products such as penicillin, the cholesterol lowering drug lovastatin, in addition to several toxins, the most famous being aflatoxin. The genetic regulation of fungal natural products is coupled with developmental differentiation through a conserved protein complex termed the velvet complex. The founding member of the complex, velvet (VeA), is a light-regulated protein that shuttles between the cytoplasm and nucleus in response to illumination. Once in the nucleus, VeA interacts with the putative methyltransferase LaeA to positively regulate production of secondary metabolites and with VelB to induce sexual development. We have identified a new interaction partner of VeA that has sequence homology to LaeA. The putative LaeA-like methyltransferase LlmF controls the subcellular localization of VeA in response to light, thereby regulating the downstream outputs of secondary metabolism and development. While the mechanism of the velvet complex remains an enigma, our data suggest that manipulation of protein subcellular localization is an approach that can be used to control production of secondary metabolites.
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Al Abdallah Q, Choe SI, Campoli P, Baptista S, Gravelat FN, Lee MJ, Sheppard DC. A conserved C-terminal domain of the Aspergillus fumigatus developmental regulator MedA is required for nuclear localization, adhesion and virulence. PLoS One 2012. [PMID: 23185496 PMCID: PMC3503810 DOI: 10.1371/journal.pone.0049959] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MedA is a developmental regulator that is conserved in the genome of most filamentous fungi. In the pathogenic fungus Aspergillus fumigatus MedA regulates conidiogenesis, adherence to host cells, and pathogenicity. The mechanism by which MedA governs these phenotypes remains unknown. Although the nuclear import of MedA orthologues has been reported in other fungi, no nuclear localization signal, DNA-binding domain or other conserved motifs have been identified within MedA. In this work, we performed a deletion analysis of MedA and identified a novel domain within the C-terminal region of the protein, designated MedA346–557, that is necessary and sufficient for nuclear localization of MedA. We further demonstrate that MedA nuclear localization is required for the function of MedA. Surprisingly, expression of the minimal nuclear localization fragment MedA346–557 alone was sufficient to restore conidogenesis, biofilm formation and virulence to the medA mutant strain. Collectively these results suggest that MedA functions in the regulation of transcription, and that the MedA346–557 domain is both necessary and sufficient to mediate MedA function.
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Affiliation(s)
- Qusai Al Abdallah
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Se-In Choe
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Paolo Campoli
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Stefanie Baptista
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Fabrice N. Gravelat
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Mark J. Lee
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Donald C. Sheppard
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
- Department of Medicine, McGill University, Montreal, Quebec, Canada
- * E-mail:
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18
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VeA regulates conidiation, gliotoxin production, and protease activity in the opportunistic human pathogen Aspergillus fumigatus. EUKARYOTIC CELL 2012; 11:1531-43. [PMID: 23087369 DOI: 10.1128/ec.00222-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Invasive aspergillosis by Aspergillus fumigatus is a leading cause of infection-related mortality in immunocompromised patients. In this study, we show that veA, a major conserved regulatory gene that is unique to fungi, is necessary for normal morphogenesis in this medically relevant fungus. Although deletion of veA results in a strain with reduced conidiation, overexpression of this gene further reduced conidial production, indicating that veA has a major role as a regulator of development in A. fumigatus and that normal conidiation is only sustained in the presence of wild-type VeA levels. Furthermore, our studies revealed that veA is a positive regulator in the production of gliotoxin, a secondary metabolite known to be a virulent factor in A. fumigatus. Deletion of veA resulted in a reduction of gliotoxin production with respect to that of the wild-type control. This reduction in toxin coincided with a decrease in gliZ and gliP expression, which is necessary for gliotoxin biosynthesis. Interestingly, veA also influences protease activity in this organism. Specifically, deletion of veA resulted in a reduction of protease activity; this is the first report of a veA homolog with a role in controlling fungal hydrolytic activity. Although veA affects several cellular processes in A. fumigatus, pathogenicity studies in a neutropenic mouse infection model indicated that veA is dispensable for virulence.
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19
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Ramamoorthy V, Shantappa S, Dhingra S, Calvo AM. veA-dependent RNA-pol II transcription elongation factor-like protein, RtfA, is associated with secondary metabolism and morphological development in Aspergillus nidulans. Mol Microbiol 2012; 85:795-814. [PMID: 22783880 PMCID: PMC3418472 DOI: 10.1111/j.1365-2958.2012.08142.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In Aspergillus nidulans the global regulatory gene veA is necessary for the biosynthesis of several secondary metabolites, including the mycotoxin sterigmatocystin (ST). In order to identify additional veA-dependent genetic elements involved in regulating ST production, we performed a mutagenesis on a deletion veA (ΔveA) strain to obtain revertant mutants (RM) that regained the capability to produce toxin. Genetic analysis and molecular characterization of one of the revertant mutants, RM3, revealed that a point mutation occurred at the coding region of the rtfA gene, encoding a RNA-pol II transcription elongation factor-like protein, similar to Saccharomyces cerevisiae Rtf1. The A. nidulans rtfA gene product accumulates in nuclei. Deletion of rtfA gene in a ΔveA background restored mycotoxin production in a medium-dependent manner. rtfA also affects the production of other metabolites including penicillin. Biosynthesis of this antibiotic decreased in the absence of rtfA. Furthermore, rtfA is necessary for normal morphological development. Deletion of the rtfA gene in wild-type strains (veA+) resulted in a slight decrease in growth rate, drastic reduction in conidiation, and complete loss of sexual development. This is the first study of an Rtf1 like gene in filamentous fungi. We found rtfA putative orthologues extensively conserved in numerous fungal species.
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Affiliation(s)
| | | | | | - Ana M. Calvo
- Author to whom correspondence should be addressed [telephone: (815) 753-0451; fax (815) 753-0461;
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20
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Abstract
Genetic variation between individuals is essential to evolution and adaptation. However, intra-organismic genetic variation also shapes the life histories of many organisms, including filamentous fungi. A single fungal syncytium can harbor thousands or millions of mobile and potentially genotypically different nuclei, each having the capacity to regenerate a new organism. Because the dispersal of asexual or sexual spores propagates individual nuclei in many of these species, selection acting at the level of nuclei creates the potential for competitive and cooperative genome dynamics. Recent work in Neurospora crassa and Sclerotinia sclerotiorum has illuminated how nuclear populations are coordinated for fungal growth and other behaviors and has revealed both molecular and physical mechanisms for preventing and policing inter-genomic conflict. Recent results from population-level genomic studies in a variety of filamentous fungi suggest that nuclear exchange between mycelia and recombination between heterospecific nuclei may be of more importance to fungal evolution, diversity and the emergence of newly virulent strains than has previously been recognized.
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Affiliation(s)
- Marcus Roper
- Department of Mathematics, University of California, Berkeley, USA
- Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK
| | - Chris Ellison
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
| | - John W. Taylor
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
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21
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Markina-Iñarrairaegui A, Etxebeste O, Herrero-García E, Araújo-Bazán L, Fernández-Martínez J, Flores JA, Osmani SA, Espeso EA. Nuclear transporters in a multinucleated organism: functional and localization analyses in Aspergillus nidulans. Mol Biol Cell 2011; 22:3874-86. [PMID: 21880896 PMCID: PMC3192866 DOI: 10.1091/mbc.e11-03-0262] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nuclear transporters mediate bidirectional macromolecule traffic through the nuclear pore complex (NPC), thus participating in vital processes of eukaryotic cells. A systematic functional analysis in Aspergillus nidulans permitted the identification of 4 essential nuclear transport pathways of a hypothetical number of 14. The absence of phenotypes for most deletants indicates redundant roles for these nuclear receptors. Subcellular distribution studies of these carriers show three main distributions: nuclear, nucleocytoplasmic, and in association with the nuclear envelope. These locations are not specific to predicted roles as exportins or importins but indicate that bidirectional transport may occur coordinately in all nuclei of a syncytium. Coinciding with mitotic NPC rearrangements, transporters dynamically modified their localizations, suggesting supplementary roles to nucleocytoplasmic transport specifically during mitosis. Loss of transportin-SR and Mex/TAP from the nuclear envelope indicates absence of RNA transport during the partially open mitosis of Aspergillus, whereas nucleolar accumulation of Kap121 and Kap123 homologues suggests a role in nucleolar disassembly. This work provides new insight into the roles of nuclear transporters and opens an avenue for future studies of the molecular mechanisms of transport among nuclei within a common cytoplasm, using A. nidulans as a model organism.
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Affiliation(s)
- Ane Markina-Iñarrairaegui
- Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, National Research Council, 28040 Madrid, Spain
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22
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Wakefield L, Gadoury DM, Seem RC, Milgroom MG, Sun Q, Cadle-Davidson L. Differential gene expression during conidiation in the grape powdery mildew pathogen, Erysiphe necator. PHYTOPATHOLOGY 2011; 101:839-46. [PMID: 21405992 DOI: 10.1094/phyto-11-10-0295] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Asexual sporulation (conidiation) is coordinately regulated in the grape powdery mildew pathogen Erysiphe necator but nothing is known about its genetic regulation. We hypothesized that genes required for conidiation in other fungi would be upregulated at conidiophore initiation or full conidiation (relative to preconidiation vegetative growth and development of mature ascocarps), and that the obligate biotrophic lifestyle of E. necator would necessitate some novel gene regulation. cDNA amplified fragment length polymorphism analysis with 45 selective primer combinations produced ≈1,600 transcript-derived fragments (TDFs), of which 620 (39%) showed differential expression. TDF sequences were annotated using BLAST analysis of GenBank and of a reference transcriptome for E. necator developed by 454-FLX pyrosequencing of a normalized cDNA library. One-fourth of the differentially expressed, annotated sequences had similarity to fungal genes of unknown function. The remaining genes had annotated function in metabolism, signaling, transcription, transport, and protein fate. As expected, a portion of orthologs known in other fungi to be involved in developmental regulation was upregulated immediately prior to or during conidiation; particularly noteworthy were several genes associated with the light-dependent VeA regulatory system, G-protein signaling (Pth11 and a kelch repeat), and nuclear transport (importin-β and Ran). This work represents the first investigation into differential gene expression during morphogenesis in E. necator and identifies candidate genes and hypotheses for characterization in powdery mildews. Our results indicate that, although control of conidiation in powdery mildews may share some basic elements with established systems, there are significant points of divergence as well, perhaps due, in part, to the obligate biotrophic lifestyle of powdery mildews.
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Affiliation(s)
- Laura Wakefield
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Geneva, NY 14456, USA
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23
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Etxebeste O, Garzia A, Espeso EA, Ugalde U. Aspergillus nidulans asexual development: making the most of cellular modules. Trends Microbiol 2010; 18:569-76. [PMID: 21035346 DOI: 10.1016/j.tim.2010.09.007] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/24/2010] [Accepted: 09/28/2010] [Indexed: 11/30/2022]
Abstract
Asexual development in Aspergillus nidulans begins in superficial hyphae as the programmed emergence of successive pseudohyphal modules, collectively known as the conidiophore, and is completed by a layer of specialized cells (phialides) giving rise to chains of aerial spores. A discrete number of regulatory factors present in hyphae play different stage-specific roles in pseudohyphal modules, depending on their cellular localization and protein-protein interactions. Their multiple roles include the timely activation of a sporulation-specific pathway that governs phialide and spore formation. Such functional versatility provides for a new outlook on morphogenetic change and the ways we should study it.
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Affiliation(s)
- Oier Etxebeste
- Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, Manuel de Lardizabal, 3, 20018, San Sebastian, Spain
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Cross-talk between light and glucose regulation controls toxin production and morphogenesis in Aspergillus nidulans. Fungal Genet Biol 2010; 47:962-72. [PMID: 20816830 DOI: 10.1016/j.fgb.2010.08.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 08/17/2010] [Accepted: 08/22/2010] [Indexed: 01/11/2023]
Abstract
Light is a major environmental stimulus that has a broad effect on organisms, triggering a cellular response that results in an optimal adaptation enhancing fitness and survival. In fungi, light affects growth, and causes diverse morphological changes such as those leading to reproduction. Light can also affect fungal metabolism, including the biosynthesis of natural products. In this study we show that in Aspergillus nidulans the effect of light on the production of the sterigmatocystin (ST) toxin depends on the glucose concentration. In cultures grown with 1% glucose and exposed to light, ST production was lower than when grown in the dark. This lower ST production coincided with an elevated rate of cellular damage with partial loss of nuclear integrity and vacuolated cytoplasm. However, in cultures grown with 2% glucose these effects were reversed and light enhanced ST production. Glucose abundance also affected the light-dependent subcellular localization of the VeA (velvet) protein, a key regulator necessary for normal light-dependent morphogenesis and secondary metabolism in Aspergilli and other fungal genera. The role of other VeA-associated proteins, particularly the blue-light-sensing proteins LreA and LreB (WC-1 and WC-2 orthologs), on conidiation could also be modified by the abundance of glucose. We also show that LreA and LreB, as well as the phytochrome FphA, modulate not only the synthesis of sterigmatocystin, but also the production of the antibiotic penicillin.
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Two components of a velvet-like complex control hyphal morphogenesis, conidiophore development, and penicillin biosynthesis in Penicillium chrysogenum. EUKARYOTIC CELL 2010; 9:1236-50. [PMID: 20543063 DOI: 10.1128/ec.00077-10] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Penicillium chrysogenum is the industrial producer of the antibiotic penicillin, whose biosynthetic regulation is barely understood. Here, we provide a functional analysis of two major homologues of the velvet complex in P. chrysogenum, which we have named P. chrysogenum velA (PcvelA) and PclaeA. Data from array analysis using a DeltaPcvelA deletion strain indicate a significant role of PcVelA on the expression of biosynthesis and developmental genes, including PclaeA. Northern hybridization and high-performance liquid chromatography quantifications of penicillin titers clearly show that both PcVelA and PcLaeA play a major role in penicillin biosynthesis in a producer strain that underwent several rounds of UV mutagenesis during a strain improvement program. Both regulators are further involved in different developmental processes. While PcvelA deletion leads to light-independent conidial formation, dichotomous branching of hyphae, and pellet formation in shaking cultures, a DeltaPclaeA strain shows a severe impairment in conidiophore formation under both light and dark conditions. Bimolecular fluorescence complementation assays provide evidence for a velvet-like complex in P. chrysogenum, with structurally conserved components that have distinct developmental roles, illustrating the functional plasticity of these regulators in genera other than Aspergillus.
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26
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Analysis of a novel calcium auxotrophy in Aspergillus nidulans. Fungal Genet Biol 2010; 47:647-55. [PMID: 20438880 PMCID: PMC2884188 DOI: 10.1016/j.fgb.2010.04.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 04/06/2010] [Accepted: 04/07/2010] [Indexed: 12/23/2022]
Abstract
In Aspergillus nidulans a combination of null mutations in halA, encoding a protein kinase, and sltA, encoding a zinc-finger transcription factor having no yeast homologues, results in an elevated calcium requirement (‘calcium auxotrophy’) without impairing net calcium uptake. sltA− (±halA−) mutations result in hypertrophy of the vacuolar system. In halA−sltA− (and sltA−) strains, transcript levels for pmcA and pmcB, encoding vacuolar Ca2+-ATPase homologues, are highly elevated, suggesting a regulatory relationship between vacuolar membrane area and certain vacuolar membrane ATPase levels. Deletion of both pmcA and pmcB strongly suppresses the ‘calcium auxotrophy’. Therefore the ‘calcium auxotrophy’ possibly results from excessive vacuolar calcium sequestration, causing cytosolic calcium deprivation. Null mutations in nhaA, homologous to Saccharomyces cerevisiaeNHA1, encoding a plasma membrane Na+/H+ antiporter effluxing Na+ and K+, and a non-null mutation in trkB, homologous to S. cerevisiaeTRK1, encoding a plasma membrane high affinity K+ transporter, also suppress the calcium auxotrophy.
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