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Mohamed NZ, Shaban L, Safan S, El-Sayed ASA. Physiological and metabolic traits of Taxol biosynthesis of endophytic fungi inhabiting plants: Plant-microbial crosstalk, and epigenetic regulators. Microbiol Res 2023; 272:127385. [PMID: 37141853 DOI: 10.1016/j.micres.2023.127385] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 04/08/2023] [Accepted: 04/09/2023] [Indexed: 05/06/2023]
Abstract
Attenuating the Taxol productivity of fungi with the subculturing and storage under axenic conditions is the challenge that halts the feasibility of fungi to be an industrial platform for Taxol production. This successive weakening of Taxol productivity by fungi could be attributed to the epigenetic down-regulation and molecular silencing of most of the gene clusters encoding Taxol biosynthetic enzymes. Thus, exploring the epigenetic regulating mechanisms controlling the molecular machinery of Taxol biosynthesis could be an alternative prospective technology to conquer the lower accessibility of Taxol by the potent fungi. The current review focuses on discussing the different molecular approaches, epigenetic regulators, transcriptional factors, metabolic manipulators, microbial communications and microbial cross-talking approaches on restoring and enhancing the Taxol biosynthetic potency of fungi to be industrial platform for Taxol production.
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Affiliation(s)
- Nabil Z Mohamed
- Enzymology and Fungal Biotechnology Lab, Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt
| | - Lamis Shaban
- Enzymology and Fungal Biotechnology Lab, Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt.
| | - Samia Safan
- Enzymology and Fungal Biotechnology Lab, Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt
| | - Ashraf S A El-Sayed
- Enzymology and Fungal Biotechnology Lab, Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt.
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2
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The Heterotrimeric Transcription Factor CCAAT-Binding Complex and Ca 2+-CrzA Signaling Reversely Regulate the Transition between Fungal Hyphal Growth and Asexual Reproduction. mBio 2021; 12:e0300721. [PMID: 34781745 PMCID: PMC8593669 DOI: 10.1128/mbio.03007-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The life cycle of filamentous fungi generally comprises hyphal growth and asexual reproduction. Both growth and propagation processes are critical for invasion growth, spore dissemination, and virulence in fungal pathogens and for the production of secondary metabolites or for biomass accumulation in industrial filamentous fungi. The CCAAT-binding complex (CBC) is a heterotrimeric transcription factor comprising three subunits, HapB, HapC, and HapE, and is highly conserved in fungi. Previous studies revealed that CBC regulates sterol metabolism by repressing several genes in the ergosterol biosynthetic pathway in the human fungal pathogen Aspergillus fumigatus. In the present study, we found dysfunction of CBC caused the abnormal asexual reproduction (conidiation) in submerged liquid culture. CBC suppresses the activation of the brlA gene in the central regulatory pathway for conidiation combined with its upstream regulators fluG, flbD, and flbC by binding to the 5'-CCAAT-3' motif within conidiation gene promoters, and lack of CBC member HapB results in the upregulation of these genes. Furthermore, when the expression of brlA or flbC is repressed, the submerged conidiation does not happen in the hapB mutant. Interestingly, deletion of HapB leads to enhanced transient cytosolic Ca2+ levels and activates conidiation-positive inducer Ca2+-CrzA modules to enhance submerged conidiation, demonstrating that CrzA works with CBC as a reverse regulator of fungal conidiation. To the best of our knowledge, the finding of this study is the first report for the molecular switch mechanism between vegetative hyphal growth and asexual development regulated by CBC, in concert with Ca2+-CrzA signaling in A. fumigatus. IMPORTANCE A precisely timed switch between vegetative hyphal growth and asexual development is a crucial process for the filamentous fungal long-term survival, dissemination, biomass production, and virulence. However, under the submerged culture condition, filamentous fungi would undergo constant vegetative growth whereas asexual conidiation rarely occurs. Knowledge about possible regulators is scarce, and how they could inhibit conidiation in liquid culture is poorly understood. Here, we demonstrated that the transcription factor heterotrimeric CBC dominantly maintains vegetative growth in liquid-submerged cultures by directly suppressing the conidiation-inductive signal. In contrast, calcium and the transcription factor CrzA, are positive inducers of conidiation. Our new insights into the CBC and Ca2+-CrzA regulatory system for transition control in the submerged conidiation of A. fumigatus may have broad repercussions for all filamentous fungi. Moreover, our elucidation of the molecular mechanism for submerged conidiation may support new strategies to precisely control vegetative growth and asexual conidiation in aspergilli used in industry.
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Zhang C, Gao L, Ren Y, Gu H, Zhang Y, Lu L. The CCAAT-binding complex mediates azole susceptibility of Aspergillus fumigatus by suppressing SrbA expression and cleavage. Microbiologyopen 2021; 10:e1249. [PMID: 34964293 PMCID: PMC8608569 DOI: 10.1002/mbo3.1249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/20/2021] [Accepted: 10/20/2021] [Indexed: 11/10/2022] Open
Abstract
In fungal pathogens, the transcription factor SrbA (a sterol regulatory element-binding protein, SREBP) and CBC (CCAAT binding complex) have been reported to regulate azole resistance by competitively binding the TR34 region (34 mer) in the promoter of the drug target gene, erg11A. However, current knowledge about how the SrbA and CBC coordinately mediate erg11A expression remains limited. In this study, we uncovered a novel relationship between HapB (a subunit of CBC) and SrbA in which deletion of hapB significantly prolongs the nuclear retention of SrbA by increasing its expression and cleavage under azole treatment conditions, thereby enhancing Erg11A expression for drug resistance. Furthermore, we verified that loss of HapB significantly induces the expression of the rhomboid protease RbdB, Dsc ubiquitin E3 ligase complex, and signal peptide peptidase SppA, which are required for the cleavage of SrbA, suggesting that HapB acts as a repressor for these genes which contribute to the activation of SrbA by proteolytic cleavage. Together, our study reveals that CBC functions not only to compete with SrbA for binding to erg11A promoter region but also to affect SrbA expression, cleavage, and translocation to nuclei for the function, which ultimately regulate Erg11A expression and azole resistance.
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Affiliation(s)
- Chi Zhang
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
| | - Lu Gao
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
| | - Yiran Ren
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
| | - Huiyu Gu
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
| | - Yuanwei Zhang
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for MicrobiologyCollege of Life SciencesNanjing Normal UniversityNanjingChina
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Khan I, Xie WL, Yu YC, Sheng H, Xu Y, Wang JQ, Debnath SC, Xu JZ, Zheng DQ, Ding WJ, Wang PM. Heteroexpression of Aspergillus nidulans laeA in Marine-Derived Fungi Triggers Upregulation of Secondary Metabolite Biosynthetic Genes. Mar Drugs 2020; 18:md18120652. [PMID: 33352941 PMCID: PMC7766385 DOI: 10.3390/md18120652] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/04/2020] [Accepted: 12/15/2020] [Indexed: 11/26/2022] Open
Abstract
Fungi are a prospective resource of bioactive compounds, but conventional methods of drug discovery are not effective enough to fully explore their metabolic potential. This study aimed to develop an easily attainable method to elicit the metabolic potential of fungi using Aspergillus nidulans laeA as a transcription regulation tool. In this study, functional analysis of Aspergillus nidulans laeA (AnLaeA) and Aspergillus sp. Z5 laeA (Az5LaeA) was done in the fungus Aspergillus sp. Z5. Heterologous AnLaeA-and native Az5LaeA-overexpression exhibited similar phenotypic effects and caused an increase in production of a bioactive compound diorcinol in Aspergillus sp. Z5, which proved the conserved function of this global regulator. In particular, heteroexpression of AnLaeA showed a significant impact on the expression of velvet complex genes, diorcinol synthesis-related genes, and different transcription factors (TFs). Moreover, heteroexpression of AnLaeA influenced the whole genome gene expression of Aspergillus sp. Z5 and triggered the upregulation of many genes. Overall, these findings suggest that heteroexpression of AnLaeA in fungi serves as a simple and easy method to explore their metabolic potential. In relation to this, AnLaeA was overexpressed in the fungus Penicillium sp. LC1-4, which resulted in increased production of quinolactacin A.
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Nardone V, Chaves-Sanjuan A, Lapi M, Airoldi C, Saponaro A, Pasqualato S, Dolfini D, Camilloni C, Bernardini A, Gnesutta N, Mantovani R, Nardini M. Structural Basis of Inhibition of the Pioneer Transcription Factor NF-Y by Suramin. Cells 2020; 9:E2370. [PMID: 33138093 PMCID: PMC7692634 DOI: 10.3390/cells9112370] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 12/27/2022] Open
Abstract
NF-Y is a transcription factor (TF) comprising three subunits (NF-YA, NF-YB, NF-YC) that binds with high specificity to the CCAAT sequence, a widespread regulatory element in gene promoters of prosurvival, cell-cycle-promoting, and metabolic genes. Tumor cells undergo "metabolic rewiring" through overexpression of genes involved in such pathways, many of which are under NF-Y control. In addition, NF-YA appears to be overexpressed in many tumor types. Thus, limiting NF-Y activity may represent a desirable anti-cancer strategy, which is an ongoing field of research. With virtual-screening docking simulations on a library of pharmacologically active compounds, we identified suramin as a potential NF-Y inhibitor. We focused on suramin given its high water-solubility that is an important factor for in vitro testing, since NF-Y is sensitive to DMSO. By electrophoretic mobility shift assays (EMSA), isothermal titration calorimetry (ITC), STD NMR, X-ray crystallography, and molecular dynamics (MD) simulations, we showed that suramin binds to the histone fold domains (HFDs) of NF-Y, preventing DNA-binding. Our analyses, provide atomic-level detail on the interaction between suramin and NF-Y and reveal a region of the protein, nearby the suramin-binding site and poorly conserved in other HFD-containing TFs, that may represent a promising starting point for rational design of more specific and potent inhibitors with potential therapeutic applications.
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Affiliation(s)
- Valentina Nardone
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Antonio Chaves-Sanjuan
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Michela Lapi
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Cristina Airoldi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy;
| | - Andrea Saponaro
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Sebastiano Pasqualato
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Via Adamello 16, 20139 Milan, Italy;
| | - Diletta Dolfini
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Carlo Camilloni
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Andrea Bernardini
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Nerina Gnesutta
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Roberto Mantovani
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
| | - Marco Nardini
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy; (V.N.); (A.C.-S.); (M.L.); (A.S.); (D.D.); (C.C.); (A.B.); (N.G.); (R.M.)
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Hortschansky P, Haas H, Huber EM, Groll M, Brakhage AA. The CCAAT-binding complex (CBC) in Aspergillus species. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:560-570. [PMID: 27939757 DOI: 10.1016/j.bbagrm.2016.11.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND The CCAAT binding complex (CBC), consisting of a heterotrimeric core structure, is highly conserved in eukaryotes and constitutes an important general transcriptional regulator. Scope of the review. In this review we discuss the scientific history and the current state of knowledge of the multiple gene regulatory functions, protein motifs and structure of the CBC in fungi with a special focus on Aspergillus species. Major conclusions and general significance. Initially identified as a transcriptional activator of respiration in Saccharomyces cerevisiae, in other fungal species the CBC was found to be involved in highly diverse pathways, but a general rationale for its involvement was missing. Subsequently, the CBC was found to sense reactive oxygen species through oxidative modifications of cysteine residues in order to mediate redox regulation. Moreover, via interaction with the iron-sensing bZIP transcription factor HapX, the CBC was shown to mediate adaptation to both iron starvation and iron excess. Due to the control of various pathways in primary and secondary metabolism the CBC is of crucial importance for fungal virulence in both animal and plant hosts as well as antifungal resistance. Consequently, CBC-mediated control affects biological processes that are of high interest in biotechnology, agriculture and infection medicine. This article is part of a Special Issue entitled: Nuclear Factor Y in Development and Disease, edited by Prof. Roberto Mantovani.
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Affiliation(s)
- Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, D-07745, Jena, Germany
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innrain 80-82, A6020 Innsbruck, Austria
| | - Eva M Huber
- Center for Integrated Protein Science Munich at the Department Chemistry, Technische Universität München, Lichtenbergstr. 4, D-85748, Garching, Germany
| | - Michael Groll
- Center for Integrated Protein Science Munich at the Department Chemistry, Technische Universität München, Lichtenbergstr. 4, D-85748, Garching, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, D-07745, Jena, Germany; Department of Microbiology and Molecular Biology, Friedrich Schiller University (FSU), D-07745 Jena, Germany.
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7
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Nardone V, Chaves-Sanjuan A, Nardini M. Structural determinants for NF-Y/DNA interaction at the CCAAT box. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:571-580. [PMID: 27677949 DOI: 10.1016/j.bbagrm.2016.09.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 12/26/2022]
Abstract
The recently determined crystal structures of the sequence-specific transcription factor NF-Y have illuminated the structural mechanism underlying transcription at the CCAAT box. NF-Y is a trimeric protein complex composed by the NF-YA, NF-YB, and NF-YC subunits. NF-YB and NF-YC contain a histone-like domain and assemble on a head-to-tail fashion to form a dimer, which provides the structural scaffold for the DNA sugar-phosphate backbone binding (mimicking the nucleosome H2A/H2B-DNA assembly) and for the interaction with NF-YA. The NF-YA subunit hosts two structurally extended α-helices; one is involved in NF-YB/NF-YC binding and the other inserts deeply into the DNA minor groove, providing exquisite sequence-specificity for recognition and binding of the CCAAT box. The analysis of these structural data is expected to serve as a powerful guide for future experiments aimed at understanding the role of post-translational modification at NF-Y regulation sites and to unravel the three-dimensional architecture of higher order complexes formed between NF-Y and other transcription factors that act synergistically for transcription activation. Moreover, these structures represent an excellent starting point to challenge the formation of a stable hybrid nucleosome between NF-Y and core histone proteins, and to rationalize the fine molecular details associated with the wide combinatorial association of plant NF-Y subunits. This article is part of a Special Issue entitled: Nuclear Factor Y in Development and Disease, edited by Prof. Roberto Mantovani.
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Affiliation(s)
- Valentina Nardone
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
| | - Antonio Chaves-Sanjuan
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
| | - Marco Nardini
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
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9
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Huber E, Scharf D, Hortschansky P, Groll M, Brakhage A. DNA Minor Groove Sensing and Widening by the CCAAT-Binding Complex. Structure 2012; 20:1757-68. [DOI: 10.1016/j.str.2012.07.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 07/24/2012] [Accepted: 07/27/2012] [Indexed: 10/28/2022]
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10
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Yin W, Keller NP. Transcriptional regulatory elements in fungal secondary metabolism. J Microbiol 2011; 49:329-39. [PMID: 21717315 DOI: 10.1007/s12275-011-1009-1] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 03/15/2011] [Indexed: 01/19/2023]
Abstract
Filamentous fungi produce a variety of secondary metabolites of diverse beneficial and detrimental activities to humankind. The genes required for a given secondary metabolite are typically arranged in a gene cluster. There is considerable evidence that secondary metabolite gene regulation is, in part, by transcriptional control through hierarchical levels of transcriptional regulatory elements involved in secondary metabolite cluster regulation. Identification of elements regulating secondary metabolism could potentially provide a means of increasing production of beneficial metabolites, decreasing production of detrimental metabolites, aid in the identification of 'silent' natural products and also contribute to a broader understanding of molecular mechanisms by which secondary metabolites are produced. This review summarizes regulation of secondary metabolism associated with transcriptional regulatory elements from a broad view as well as the tremendous advances in discovery of cryptic or novel secondary metabolites by genomic mining.
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Affiliation(s)
- Wenbing Yin
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Nakajima Y, Saitoh KI, Arie T, Teraoka T, Kamakura T. Expression specificity of CBP1 is regulated by transcriptional repression during vegetative growth of Magnaporthe oryzae. J GEN APPL MICROBIOL 2011; 56:437-45. [PMID: 21282899 DOI: 10.2323/jgam.56.437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The rice blast fungus Magnaporthe oryzae produces appressoria during the infection of a host. In M. oryzae, the appressorium formation-related gene CBP1 (Chitin Binding Protein 1) is specifically expressed during the early stage of appressorium differentiation. The transcription factor CON7 activates CBP1 expression. However, many aspects of the regulation of CBP1 expression are still unknown. In this report, the CBP1 5' upstream region was analyzed using an egfp reporter. Deletion of the CBP1 5 ' upstream region caused derepression of reporter gene activity during vegetative growth. This result suggests that CBP1 expression is repressed during vegetative growth. The key 5 ' upstream sequences for CBP1 repression were examined. Furthermore, cis- and trans-acting elements of the negative regulatory region were investigated. Here, we discuss the transcriptional regulatory mechanism of CBP1.
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Affiliation(s)
- Yuichi Nakajima
- Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
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12
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Thön M, Al Abdallah Q, Hortschansky P, Scharf DH, Eisendle M, Haas H, Brakhage AA. The CCAAT-binding complex coordinates the oxidative stress response in eukaryotes. Nucleic Acids Res 2009; 38:1098-113. [PMID: 19965775 PMCID: PMC2831313 DOI: 10.1093/nar/gkp1091] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The heterotrimeric CCAAT-binding complex is evolutionary conserved in eukaryotic organisms. The corresponding Aspergillus nidulans CCAAT- binding factor (AnCF) consists of the subunits HapB, HapC and HapE. All of the three subunits are necessary for DNA binding. Here, we demonstrate that AnCF senses the redox status of the cell via oxidative modification of thiol groups within the histone fold motif of HapC. Mutational and in vitro interaction analyses revealed that two of these cysteine residues are indispensable for stable HapC/HapE subcomplex formation and high-affinity DNA binding of AnCF. Oxidized HapC is unable to participate in AnCF assembly and localizes in the cytoplasm, but can be recycled by the thioredoxin system in vitro and in vivo. Furthermore, deletion of the hapC gene led to an impaired oxidative stress response. Therefore, the central transcription factor AnCF is regulated at the post-transcriptional level by the redox status of the cell serving for a coordinated activation and deactivation of antioxidative defense mechanisms including the specific transcriptional activator NapA, production of enzymes such as catalase, thioredoxin or peroxiredoxin, and maintenance of a distinct glutathione homeostasis. The underlying fine-tuned mechanism very likely represents a general feature of the CCAAT-binding complexes in eukaryotes.
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Affiliation(s)
- Marcel Thön
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstrasse 11a, D-07745 Jena, Germany
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13
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Hortschansky P, Eisendle M, Al-Abdallah Q, Schmidt AD, Bergmann S, Thön M, Kniemeyer O, Abt B, Seeber B, Werner ER, Kato M, Brakhage AA, Haas H. Interaction of HapX with the CCAAT-binding complex--a novel mechanism of gene regulation by iron. EMBO J 2007; 26:3157-68. [PMID: 17568774 PMCID: PMC1914100 DOI: 10.1038/sj.emboj.7601752] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 05/16/2007] [Indexed: 11/08/2022] Open
Abstract
Iron homeostasis requires subtle control systems, as iron is both essential and toxic. In Aspergillus nidulans, iron represses iron acquisition via the GATA factor SreA, and induces iron-dependent pathways at the transcriptional level, by a so far unknown mechanism. Here, we demonstrate that iron-dependent pathways (e.g., heme biosynthesis) are repressed during iron-depleted conditions by physical interaction of HapX with the CCAAT-binding core complex (CBC). Proteome analysis identified putative HapX targets. Mutual transcriptional control between hapX and sreA and synthetic lethality resulting from deletion of both regulatory genes indicate a tight interplay of these control systems. Expression of genes encoding CBC subunits was not influenced by iron availability, and their deletion was deleterious during iron-depleted and iron-replete conditions. Expression of hapX was repressed by iron and its deletion was deleterious during iron-depleted conditions only. These data indicate that the CBC has a general role and that HapX function is confined to iron-depleted conditions. Remarkably, CBC-mediated regulation has an inverse impact on the expression of the same gene set in A. nidulans, compared with Saccharomyces cerevisae.
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Affiliation(s)
- Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Martin Eisendle
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Qusai Al-Abdallah
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - André D Schmidt
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Sebastian Bergmann
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Marcel Thön
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
| | - Beate Abt
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Birgit Seeber
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Ernst R Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | - Masashi Kato
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Jena, Germany
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), and Friedrich-Schiller-University Jena, Beutenbergstrasse 11a, 07745 Jena, Germany. Tel.: +49 3641 656601; Fax: +49 3641 656603; E-mail:
| | - Hubertus Haas
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
- Division of Molecular Biology, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, 6020 Innsbruck, Austria. Tel.: +43 512 9003 70205; Fax: +43 512 9003 73100; E-mail:
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14
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Ronen R, Sharon H, Levdansky E, Romano J, Shadkchan Y, Osherov N. The Aspergillus nidulans pkcA gene is involved in polarized growth, morphogenesis and maintenance of cell wall integrity. Curr Genet 2007; 51:321-9. [PMID: 17406869 DOI: 10.1007/s00294-007-0129-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2007] [Accepted: 03/10/2007] [Indexed: 10/23/2022]
Abstract
The protein kinase C (PKC) family participates in maintaining integrity and growth of fungal cell walls. However, the precise molecular role of these proteins in the filamentous fungi remains unknown. In this work, pkcA, the gene encoding the PKC homolog in the filamentous fungus Aspergillus nidulans, was cloned and its function analyzed using a conditional alcA-PKC mutant strain. Repression of pkcA expression resulted in increased conidial swelling, decreased rates of hyphal growth, changes in the ultrastructure of the cell wall and increased sensitivity to antifungal agents. These results suggest that the protein encoded by pkcA is involved in key aspects of cell morphogenesis and cell wall integrity.
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Affiliation(s)
- Revital Ronen
- Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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15
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Cary JW, Ehrlich KC. Aflatoxigenicity in Aspergillus: molecular genetics, phylogenetic relationships and evolutionary implications. Mycopathologia 2006; 162:167-77. [PMID: 16944284 DOI: 10.1007/s11046-006-0051-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Aflatoxins (AFs) are toxic and carcinogenic secondary metabolites produced by isolates of Aspergillus section Flavi as well as a number of Aspergillus isolates that are classified outside of section Flavi. Characterization of the AF and sterigmatocystin (ST) gene clusters and analysis of factors governing regulation of their biosynthesis has resulted in these two mycotoxins being the most extensively studied of fungal secondary metabolites. This wealth of information has allowed the determination of the molecular basis for non-production of AF in natural isolates of A. flavus and domesticated strains of A. oryzae. This review provides an overview of the molecular analysis of the AF and ST gene clusters as well as new information on an AF gene cluster identified in the non-section Flavi isolate, Aspergillus ochraceoroseus. Additionally, molecular phylogenetic analysis using AF biosynthetic gene sequences as well as ribosomal DNA internal transcribed spacer (ITS) sequences between various section Flavi and non-section Flavi species has enabled determination of the probable evolutionary history of the AF and ST gene clusters. A model for the evolution of the AF and ST gene clusters as well as possible biological roles for AF are discussed.
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Affiliation(s)
- Jeffrey W Cary
- USDA, ARS, Southern Regional Research Center, 1100 Robert E. Lee Blvd., New Orleans, LA 70124, USA.
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16
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Verma M, Rawool S, Bhat PJ, Venkatesh KV. Biological significance of autoregulation through steady state analysis of genetic networks. Biosystems 2006; 84:39-48. [PMID: 16377074 DOI: 10.1016/j.biosystems.2005.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 10/06/2005] [Accepted: 10/12/2005] [Indexed: 11/22/2022]
Abstract
Autoregulation of regulatory proteins is a recurring theme in genetic networks. Autoregulation is an important component of a genetic regulatory network besides protein-protein and protein-DNA interactions, stoichiometry, multiple binding sites and cooperativity. Although the biological significance of autoregulation has been studied before, its significance in presence of other mechanisms is not clearly enumerated. We have analyzed at steady state the significance of autoregulation in presence of other molecular mechanisms by considering hypothetical genetic networks. We demonstrate that autoregulation of a regulatory protein can impart amplification to the response. Further, autoregulation of an activator binding to the DNA as a dimer can introduce bistability, thus forcing the system to reside in two distinct steady states. In combination with autoregulation, cooperative binding can further increase the sensitivity and can yield a highly ultrasensitive response. We conclude that autoregulation with the help of other molecular mechanisms can impart distinct system level properties such as amplification, sensitivity and bistability. The results are further discussed in relation to various examples of genetic networks that exist in biological systems.
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Affiliation(s)
- Malkhey Verma
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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17
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Tüncher A, Spröte P, Gehrke A, Brakhage AA. The CCAAT-binding Complex of Eukaryotes: Evolution of a Second NLS in the HapB Subunit of the Filamentous Fungus Aspergillus nidulans Despite Functional Conservation at the Molecular Level between Yeast, A.nidulans and Human. J Mol Biol 2005; 352:517-33. [PMID: 16098534 DOI: 10.1016/j.jmb.2005.06.068] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 06/24/2005] [Accepted: 06/29/2005] [Indexed: 11/22/2022]
Abstract
The heterotrimeric CCAAT-binding complex is evolutionarily conserved in eukaryotic organisms, including fungi, plants and mammals. In the filamentous fungus Aspergillus nidulans, the corresponding complex was designated AnCF (A.nidulans CCAAT-binding factor). AnCF consists of the subunits HapB, HapC and HapE. All three subunits are necessary for DNA binding. HapB contains two putative nuclear localisation signal sequences (NLSs) designated NLS1 and NLS2. Previously, it was shown that only NLS2 was required for nuclear localisation of HapB. Furthermore, HapC and HapE are transported to the nucleus only in complex with HapB via a piggy back mechanism. Here, by using various GFP constructs and by establishing a novel marker gene for transformation of A.nidulans, i.e. the pabaA gene encoding p-aminobenzoic acid synthase, it was shown that the HapB homologous proteins of both Saccharomyces cerevisiae (Hap2p) and human (NF-YA) use an NLS homologous to HapB NLS1 for nuclear localisation in S.cerevisiae. Interestingly, for A.nidulans HapB, NLS1 was sufficient for nuclear localisation in S.cerevisiae. In A.nidulans, HapB NLS1 was also functional when present in a different protein context. However, in A.nidulans, both S.cerevisiae Hap2p and human NF-YA entered the nucleus only when HapB NLS2 was present in the respective proteins. In that case, both proteins Hap2p and NF-YA complemented, at least in part, the hap phenotype of A.nidulans with respect to lack of growth on acetamide. Similarly, A.nidulans HapB and human NF-YA complemented a hap2 mutant of S.cerevisiae. In summary, HapB, Hap2p and NF-YA are interchangeable. Because the A.nidulans hapB mutant was complemented, at least in part, by both the human NF-YA and S.cerevisiae Hap2p this finding suggests that the piggy-back mechanism of nuclear transport found for A.nidulans is conserved in yeast and human.
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Affiliation(s)
- André Tüncher
- Department of Molecular and Applied Microbiology, Leibniz-Institute for Natural Product Research and Infection Biology-Hans-Knoell-Institute, Beutenbergstrasse 11a, D-07745 Jena, Germany
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18
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Steidl S, Tüncher A, Goda H, Guder C, Papadopoulou N, Kobayashi T, Tsukagoshi N, Kato M, Brakhage AA. A Single Subunit of a Heterotrimeric CCAAT-binding Complex Carries a Nuclear Localization Signal: Piggy Back Transport of the Pre-assembled Complex to the Nucleus. J Mol Biol 2004; 342:515-24. [PMID: 15327951 DOI: 10.1016/j.jmb.2004.07.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Revised: 07/07/2004] [Accepted: 07/12/2004] [Indexed: 10/26/2022]
Abstract
An unresolved question concerns the nuclear localization of the heterotrimeric CCAAT-binding complex, which is evolutionarily conserved in eukaryotic organisms including fungi, plants and mammals. All three subunits are necessary for DNA binding. In the filamentous fungus Aspergillus nidulans the corresponding complex was designated AnCF (A.nidulans CCAAT-binding factor). AnCF consists of the HapB, HapC and HapE subunits. Here, by using various green fluorescent protein constructs, a nuclear localization signal sequence (NLS) of the HapB protein was identified, outside of the evolutionarily conserved domain. HapB-EGFP was transported into the nucleus in both DeltahapC and DeltahapE strains, indicating that its NLS interacts with the import machinery independently of the other Hap subunits. In contrast, HapC-EGFP did not enter the nucleus in the absence of HapE or HapB. A similar finding was made for HapE-EGFP, which did not localize to the nucleus in the absence of HapC or HapB. Addition of the HapB-NLS to either HapC or HapE led to nuclear localization of the respective protein fusions, indicating that both HapC and HapE lack a functional NLS. Furthermore, these data strongly suggest that HapC and HapE have first to form a heterodimer and can be transported only as a heterodimer via the HapB protein into the nucleus. Therefore, the HapB subunit is the primary cargo for the import machinery, while HapC and HapE are transported to the nucleus only as a heterodimer and in complex with HapB via a piggy back mechanism. This enables the cell to provide equimolar concentrations of all subunits to the nucleus.
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Affiliation(s)
- Stefan Steidl
- Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
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19
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Tüncher A, Reinke H, Martic G, Caruso ML, Brakhage AA. A basic-region helix-loop-helix protein-encoding gene (devR) involved in the development of Aspergillus nidulans. Mol Microbiol 2004; 52:227-41. [PMID: 15049823 DOI: 10.1111/j.1365-2958.2003.03961.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Basic-region helix-loop-helix (bHLH) proteins form an interesting class of eukaryotic transcription factors often involved in developmental processes. Here, a so far unknown bHLH protein-encoding gene of the filamentous ascomycete Aspergillus nidulans was isolated and designated devR for regulator of development. Deletion of devR revealed that the gene is non-essential for vegetative growth. However, the deletion mutant produced wrinkled colonies, a yellow pigment and did not form conidia on minimal agar plates. Conidiophore development was initiated normally, and colonies produced conidiophores with metulae and phialides. However, the phialides continued to grow filamentously and produced a second conidiophore with a vesicle at its end. The addition of KCl (0.6 M) to the medium suppressed the knock-out phenotype. The DeltadevR phenotype resembled that of a mutation in the tcsA gene encoding a histidine kinase domain and a response regulator domain. Here, we generated a tcsA deletion mutant. In a DeltatcsA strain, a DevR-Egfp protein fusion was detected in the cytoplasm, whereas in the wild type, the protein fusion was exclusively located in the nuclei, indicating that TcsA is required for nuclear localization of DevR. devR mRNA steady-state levels were similar in sporulating and vegetatively growing mycelia, and independent of a functional brlA gene. Moreover, under all conditions tested, self-crossing of the DeltadevR mutant strain was never observed. Taken together, devR encodes a bHLH regulatory protein that is part of the tcsA signal transduction network and required for development under standard growth conditions.
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Affiliation(s)
- André Tüncher
- Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, D-30167 Hannover, Germany
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20
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Abstract
Infections with mold pathogens have emerged as an increasing risk faced by patients under sustained immunosuppression. Species of the Aspergillus family account for most of these infections, and in particular Aspergillus fumigatus may be regarded as the most important airborne pathogenic fungus. The improvement in transplant medicine and the therapy of hematological malignancies is often complicated by the threat of invasive aspergillosis. Specific diagnostic methods are still limited as are the possibilities of therapeutic intervention, leading to the disappointing fact that invasive aspergillosis is still associated with a high mortality rate that ranges from 30% to 90%. In recent years considerable progress has been made in understanding the genetics of A. fumigatus, and molecular techniques for the manipulation of the fungus have been developed. Molecular genetics offers not only approaches for the detailed characterization of gene products that appear to be key components of the infection process but also selection strategies that combine classical genetics and molecular biology to identify virulence determinants of A. fumigatus. Moreover, these methods have a major impact on the development of novel strategies leading to the identification of antimycotic drugs. This review summarizes the current knowledge on the biology, molecular genetics, and genomics of A. fumigatus.
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Affiliation(s)
- Axel A Brakhage
- Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, Germany.
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21
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Caruso ML, Litzka O, Martic G, Lottspeich F, Brakhage AA. Novel basic-region helix-loop-helix transcription factor (AnBH1) of Aspergillus nidulans counteracts the CCAAT-binding complex AnCF in the promoter of a penicillin biosynthesis gene. J Mol Biol 2002; 323:425-39. [PMID: 12381299 DOI: 10.1016/s0022-2836(02)00965-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cis-acting CCAAT elements are found frequently in eukaryotic promoter regions. Many of the genes containing such elements in their promoters are regulated by a conserved multimeric CCAAT-binding complex. In the fungus Emericella (Aspergillus) nidulans, this complex was designated AnCF (A.nidulans CCAAT-binding factor). AnCF regulates several genes, including the penicillin biosynthesis genes ipnA and aatA. Since it is estimated that the CCAAT-binding complex regulates more than 200 genes, an important question concerns the regulation mechanism that allows so many genes to be regulated by a single complex in a gene-specific manner. One of the answers to this question appears to lie in the interaction of AnCF with other transcription factors. Here, a novel transcription factor designated AnBH1 was isolated. The corresponding anbH1 gene was cloned and found to be located on chromosome IV. The deduced AnBH1 protein belongs to the family of basic-region helix-loop-helix (bHLH) transcription factors. AnBH1 binds in vitro as a homodimer to an, not previously described, asymmetric E-box within the aatA promoter that overlaps with the AnCF-binding site. This is the first report demonstrating that the CCAAT-binding complex and a bHLH transcription factor bind to overlapping sites. Since deletion of anbH1 appears to be lethal, the anbH1 gene was replaced by a regulatable alcAp-anbH1 gene fusion. The analysis of aatAp-lacZ expression in such a strain indicated that AnBH1 acts as a repressor of aatA gene expression and therefore counteracts the positive action of AnCF.
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Affiliation(s)
- Maria Louise Caruso
- Institut für Mikrobiologie, Universität Hannover, Schneiderberg 50, 30167 Hannover, Germany
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22
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Kato M, Tateyama Y, Hayashi K, Naruse F, Oonishi R, Tanoue S, Tanaka A, Kobayashi T, Tsukagoshi N. A quantity control mechanism regulating levels of the HapE subunit of the Hap complex in Aspergillus nidulans: no accumulation of HapE in hapC deletion mutants. FEBS Lett 2002; 512:227-9. [PMID: 11852085 DOI: 10.1016/s0014-5793(02)02266-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Aspergillus nidulans CCAAT-binding complex (Hap complex) consists of at least three subunits, HapB, HapC and HapE. To investigate the quantity control mechanisms of the subunits during assembly of the Hap complex, reconstitution studies with the recombinant subunits and extracts prepared from the respective hap subunit deletion mutants were carried out. Furthermore, Western blot analysis of the Hap subunits and Northern blot analysis of the hap genes with the respective deletion mutants were also performed. From all the results together, it was suggested that the number of the HapC molecule could adjust that of the HapE molecule by forming stable heterodimers prior to assembly of the Hap complex.
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Affiliation(s)
- M Kato
- Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, 464-8601, Nagoya, Japan.
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23
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The Transcription of Genes. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50031-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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