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Agirrezabala Z, Guruceaga X, Martin-Vicente A, Otamendi A, Fagoaga A, Fortwendel JR, Espeso EA, Etxebeste O. Identification and functional characterization of the putative members of the CTDK-1 kinase complex as regulators of growth and development in Aspergillus nidulans and Aspergillus fumigatus. mBio 2023; 14:e0245223. [PMID: 37943062 PMCID: PMC10746219 DOI: 10.1128/mbio.02452-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 10/03/2023] [Indexed: 11/10/2023] Open
Abstract
Asexual spores are the main vehicle used by fungi to disperse to new niches. The Eurotiomycete Aspergillus nidulans is the main reference for the study of the genetic/molecular control of asexual development. In this species, Flb proteins control the expression of the master gene brlA, and thus, loss-of-function mutations in flb (upstream developmental activation [UDA]) genes block brlA transcription and, consequently, the production of conidiophores, the structures bearing asexual spores known as conidia. However, the aconidial phenotype of specific flb mutants, such as that of the ΔflbB strain, is reverted under salt-stress conditions. Previously, we generated a collection of second-site mutants of ΔflbB unable to conidiate on culture medium supplemented with NaH2PO4 (0.65 M). Here, we identified a Gly347Stop mutation within flpA as responsible for the FLIP57 phenotype and characterized the role of the putative cyclin FlpA and the remaining putative components of the C-terminal domain kinase-1 (CTDK-1) complex in A. nidulans and Aspergillus fumigatus. FlpA, Stk47, and FlpB are necessary (i) for timely germination, (ii) in the transition from metulae to phialides (the cells generating conidia) during conidiophore development, and (iii) for the development of sexual structures (cleistothecia) in A. nidulans. The three proteins are nuclear, and the nucleoplasmic localization of Stk47 depends on the activity of FlpA, which correlates with the retention of Stk47 by FlpA in pull-down assays. Overall, this work links the putative CTDK-1 complex of aspergilli with growth and developmental control. Identification of a mutation in flpA as inhibitor of conidiation in A. nidulans and functional characterization of FlpA, Stk47 and FlpB as putative members of the C-terminal domain kinase complex CTDK-1 in A. nidulans and A. fumigatus.IMPORTANCEAspergillus fumigatus has been included by the World Health Organization in the priority list of fungal pathogens because (i) it causes 90% of invasive aspergillosis cases, with a high mortality rate, and (ii) infections are becoming increasingly resistant to azole antifungals. A. nidulans is an opportunistic pathogen and a saprotroph which has served during the last 80 years as a reference system for filamentous fungi. Here, we characterized the role in morphogenesis and development of the putative transcriptional cyclin/kinase complex CTDK-1 in both aspergilli. The null mutants of the corresponding genes showed delayed germination, aberrant conidiophore development, and inhibition of cleistothecia production. While in higher eukaryotes this complex is formed only by a cyclin and a kinase, the fungal complex would incorporate a fungal-specific third component, FlpB, which would enable the interaction between the kinase (Stk47) and the cyclin (FlpA) and may be used as a target for antifungals.
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Affiliation(s)
- Z. Agirrezabala
- Laboratory of Biology, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, UPV/EHU, San Sebastian, Spain
| | - X. Guruceaga
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - A. Martin-Vicente
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - A. Otamendi
- Laboratory of Biology, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, UPV/EHU, San Sebastian, Spain
| | - A. Fagoaga
- Laboratory of Biology, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, UPV/EHU, San Sebastian, Spain
| | - J. R. Fortwendel
- Department of Clinical Pharmacy and Translational Science, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - E. A. Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - O. Etxebeste
- Laboratory of Biology, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country, UPV/EHU, San Sebastian, Spain
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Son YE, Yu JH, Park HS. The novel spore-specific regulator SscA controls Aspergillus conidiogenesis. mBio 2023; 14:e0184023. [PMID: 37707170 PMCID: PMC10653911 DOI: 10.1128/mbio.01840-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 09/15/2023] Open
Abstract
IMPORTANCE Filamentous fungi produce myriads of asexual spores, which are the main reproductive particles that act as infectious or allergenic agents. Although the serial of asexual sporogenesis is coordinated by various genetic regulators, there remain uncharacterized transcription factors in Aspergillus. To understand the underlying mechanism of spore formation, integrity, and viability, we have performed comparative transcriptomic analyses on three Aspergillus species and found a spore-specific transcription factor, SscA. SscA has a major role in conidial formation, maturation and dormancy, and germination in Aspergillus nidulans. Functional studies indicate that SscA coordinates conidial wall integrity, amino acid production, and secondary metabolism in A. nidulans conidia. Furthermore, the roles of SscA are conserved in other Aspergillus species. Our findings that the SscA has broad functions in Aspergillus conidia will help to understand the conidiogenesis of Aspergillus species.
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Affiliation(s)
- Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
| | - Jae-Hyuk Yu
- Department of Bacteriology, Food Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, South Korea
- Department of Integrative Biology, Kyungpook National University, Daegu, South Korea
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Pandit SS, Zheng J, Yin Y, Lorber S, Puel O, Dhingra S, Espeso EA, Calvo AM. Homeobox transcription factor HbxA influences expression of over one thousand genes in the model fungus Aspergillus nidulans. PLoS One 2023; 18:e0286271. [PMID: 37478074 PMCID: PMC10361519 DOI: 10.1371/journal.pone.0286271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/11/2023] [Indexed: 07/23/2023] Open
Abstract
In fungi, conserved homeobox-domain proteins are transcriptional regulators governing development. In Aspergillus species, several homeobox-domain transcription factor genes have been identified, among them, hbxA/hbx1. For instance, in the opportunistic human pathogen Aspergillus fumigatus, hbxA is involved in conidial production and germination, as well as virulence and secondary metabolism, including production of fumigaclavines, fumiquinazolines, and chaetominine. In the agriculturally important fungus Aspergillus flavus, disruption of hbx1 results in fluffy aconidial colonies unable to produce sclerotia. hbx1 also regulates production of aflatoxins, cyclopiazonic acid and aflatrem. Furthermore, transcriptome studies revealed that hbx1 has a broad effect on the A. flavus genome, including numerous genes involved in secondary metabolism. These studies underline the importance of the HbxA/Hbx1 regulator, not only in developmental processes but also in the biosynthesis of a broad number of fungal natural products, including potential medical drugs and mycotoxins. To gain further insight into the regulatory scope of HbxA in Aspergilli, we studied its role in the model fungus Aspergillus nidulans. Our present study of the A. nidulans hbxA-dependent transcriptome revealed that more than one thousand genes are differentially expressed when this regulator was not transcribed at wild-type levels, among them numerous transcription factors, including those involved in development as well as in secondary metabolism regulation. Furthermore, our metabolomics analyses revealed that production of several secondary metabolites, some of them associated with A. nidulans hbxA-dependent gene clusters, was also altered in deletion and overexpression hbxA strains compared to the wild type, including synthesis of nidulanins A, B and D, versicolorin A, sterigmatocystin, austinol, dehydroaustinol, and three unknown novel compounds.
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Affiliation(s)
- Sandesh S. Pandit
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Jinfang Zheng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Yanbin Yin
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Sophie Lorber
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, Toulouse, France
| | - Olivier Puel
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, Toulouse, France
| | - Sourabh Dhingra
- Department of Biological Sciences and Eukaryotic Pathogen Innovation Center, Clemson University, Clemson, South Carolina, United States of America
| | - Eduardo A. Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
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Cho HJ, Son SH, Chen W, Son YE, Lee I, Yu JH, Park HS. Regulation of Conidiogenesis in Aspergillus flavus. Cells 2022; 11:cells11182796. [PMID: 36139369 PMCID: PMC9497164 DOI: 10.3390/cells11182796] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/29/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Aspergillus flavus is a representative fungal species in the Aspergillus section Flavi and has been used as a model system to gain insights into fungal development and toxin production. A. flavus has several adverse effects on humans, including the production of the most carcinogenic mycotoxin aflatoxins and causing aspergillosis in immune-compromised patients. In addition, A. flavus infection of crops results in economic losses due to yield loss and aflatoxin contamination. A. flavus is a saprophytic fungus that disperses in the ecosystem mainly by producing asexual spores (conidia), which also provide long-term survival in the harsh environmental conditions. Conidia are composed of the rodlet layer, cell wall, and melanin and are produced from an asexual specialized structure called the conidiophore. The production of conidiophores is tightly regulated by various regulators, including the central regulatory cascade composed of BrlA-AbaA-WetA, the fungi-specific velvet regulators, upstream regulators, and developmental repressors. In this review, we summarize the findings of a series of recent studies related to asexual development in A. flavus and provide insights for a better understanding of other fungal species in the section Flavi.
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Affiliation(s)
- He-Jin Cho
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Sung-Hun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Wanping Chen
- Department of Molecular Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany
| | - Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
| | - Inhyung Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 02707, Korea
| | - Jae-Hyuk Yu
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
- Department of Systems Biotechnology, Konkuk University, Seoul 05029, Korea
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Korea
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Korea
- Correspondence: ; Tel.: +82-53-950-5751
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Kück U. Special Issue “Signal Transductions in Fungi”. J Fungi (Basel) 2022; 8:jof8050528. [PMID: 35628783 PMCID: PMC9146876 DOI: 10.3390/jof8050528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/17/2022] [Indexed: 02/05/2023] Open
Abstract
In all living organisms, extracellular signals are translated into specific responses through signal transduction processes [...]
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Affiliation(s)
- Ulrich Kück
- Allgemeine & Molekulare Botanik, Ruhr-University, 44797 Bochum, Germany
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