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Jha P, Kaur T, Chhabra I, Panja A, Paul S, Kumar V, Malik T. Endophytic fungi: hidden treasure chest of antimicrobial metabolites interrelationship of endophytes and metabolites. Front Microbiol 2023; 14:1227830. [PMID: 37497538 PMCID: PMC10366620 DOI: 10.3389/fmicb.2023.1227830] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 06/26/2023] [Indexed: 07/28/2023] Open
Abstract
Endophytic fungi comprise host-associated fungal communities which thrive within the tissues of host plants and produce a diverse range of secondary metabolites with various bioactive attributes. The metabolites such as phenols, polyketides, saponins, alkaloids help to mitigate biotic and abiotic stresses, fight against pathogen attacks and enhance the plant immune system. We present an overview of the association of endophytic fungal communities with a plant host and discuss molecular mechanisms induced during their symbiotic interaction. The overview focuses on the secondary metabolites (especially those of terpenoid nature) secreted by endophytic fungi and their respective function. The recent advancement in multi-omics approaches paved the way for identification of these metabolites and their characterization via comparative analysis of extensive omics datasets. This study also elaborates on the role of diverse endophytic fungi associated with key agricultural crops and hence important for sustainability of agriculture.
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Affiliation(s)
- Priyanka Jha
- Department of Biotechnology, Lovely Faculty of Technology and Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Tamanna Kaur
- Department of Biotechnology, Lovely Faculty of Technology and Sciences, Lovely Professional University, Phagwara, Punjab, India
| | | | - Avirup Panja
- Amity Institute of Biotechnology, Amity University, Kolkata, West Bengal, India
| | - Sushreeta Paul
- Amity Institute of Biotechnology, Amity University, Kolkata, West Bengal, India
| | - Vijay Kumar
- Department of Biotechnology, Lovely Faculty of Technology and Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Tabarak Malik
- Biomedical Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
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Li Z, Sun Y, Gu L, Wang Y, Xu M, Zhou Y, Hu Y, Ma W. Ar-turmerone suppresses Aspergillus flavus growth and aflatoxin accumulation: Finding a new antifungal agent based on stored maize. Food Res Int 2023; 168:112735. [PMID: 37120196 DOI: 10.1016/j.foodres.2023.112735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 03/15/2023] [Accepted: 03/17/2023] [Indexed: 04/03/2023]
Abstract
Aspergillus flavus (A. flavus) is a common saprophytic pathogenic fungus that produces toxic and carcinogenic aflatoxins prone to contaminate food. Here, we optimized the synthesis method of Ar-turmerone, the main active ingredient in turmeric essential oil, improved its yield and reduced the operation requirements. Moreover, 50.0 μg/mL Ar-turmerone 100.0 % inhibited the colonies growth, spore germination, mycelium biomass and aflatoxin accumulation in 7 days. 2,018 differentially expressed genes (DEGs) such as catA, ppoC, erg7, erg6 and aflO related to the A. flavus growth and aflatoxin product were significantly downregulated including 45 DEGs were 100.0 % suppressed. Besides, Ar-turmerone greatly reduced A. flavus in maize, the optimal storage conditions for maize to avoid A. flavus contamination were determined as 0.940 aw, 400.0 μg/mL Ar-turmerone, and 16.0 °C. Satisfactory odor, luster, taste, and mildew in maize observed after three weeks of storage under the optimal conditions. Thus, Ar-turmerone can be used as a potential food antifungal agent against A. flavus growth and aflatoxin accumulation during food storage.
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Affiliation(s)
- Zheyu Li
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China.
| | - Yanan Sun
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, College of Food and Biological Engineering, Chengdu University, Chengdu 610106, People's Republic of China
| | - Linghui Gu
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Yuchi Wang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Mingqin Xu
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Yunhao Zhou
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China
| | - Yichen Hu
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture and Rural Affairs, College of Food and Biological Engineering, Chengdu University, Chengdu 610106, People's Republic of China.
| | - Wenbo Ma
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China.
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Biodegradation of Aflatoxin B1 in Maize Grains and Suppression of Its Biosynthesis-Related Genes Using Endophytic Trichoderma harzianum AYM3. J Fungi (Basel) 2023; 9:jof9020209. [PMID: 36836323 PMCID: PMC9964583 DOI: 10.3390/jof9020209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/27/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Aflatoxin B1 is one of the most deleterious types of mycotoxins. The application of an endophytic fungus for biodegradation or biosuppression of AFB1 production by Aspergillus flavus was investigated. About 10 endophytic fungal species, isolated from healthy maize plants, were screened for their in vitro AFs-degrading activity using coumarin medium. The highest degradation potential was recorded for Trichoderma sp. (76.8%). This endophyte was identified using the rDNA-ITS sequence as Trichoderma harzianum AYM3 and assigned an accession no. of ON203053. It caused a 65% inhibition in the growth of A. flavus AYM2 in vitro. HPLC analysis revealed that T. harzianum AYM3 had a biodegradation potential against AFB1. Co-culturing of T. harazianum AYM3 and A. flavus AYM2 on maize grains led to a significant suppression (67%) in AFB1 production. GC-MS analysis identified two AFB1-suppressing compounds, acetic acid and n-propyl acetate. Investigating effect on the transcriptional expression of five AFB1 biosynthesis-related genes in A. flavus AYM2 revealed the downregulating effects of T. harzianum AYM3 metabolites on expression of aflP and aflS genes. Using HepaRG cell line, the cytotoxicity assay indicated that T. harazianum AYM3 metabolites were safe. Based on these results, it can be concluded that T. harzianum AYM3 may be used to suppress AFB1 production in maize grains.
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Yamaguchi S, Fujioka T, Yoshimi A, Kumagai T, Umemura M, Abe K, Machida M, Kawai K. Discovery of a gene cluster for the biosynthesis of novel cyclic peptide compound, KK-1, in Curvularia clavata. FRONTIERS IN FUNGAL BIOLOGY 2023; 3:1081179. [PMID: 37746209 PMCID: PMC10512319 DOI: 10.3389/ffunb.2022.1081179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 12/15/2022] [Indexed: 09/26/2023]
Abstract
KK-1, a cyclic depsipeptide with 10 residues produced by a filamentous fungus Curvularia clavata BAUA-2787, is a promising pesticide active compound with high activity against many plant pathogens, especially Botrytis cinerea. As a first step toward the future mass production of KK-1 through synthetic biological approaches, we aimed to identify the genes responsible for the KK-1 biosynthesis. To achieve this, we conducted whole genome sequencing and transcriptome analysis of C. clavata BAUA-2787 to predict the KK-1 biosynthetic gene cluster. We then generated the overexpression and deletion mutants for each cluster gene using our originally developed transformation system for this fungus, and analyzed the KK-1 production and the cluster gene expression levels to confirm their involvement in KK-1 biosynthesis. As a result of these, a region of approximately 71 kb was found, containing 10 open reading frames, which were co-induced during KK-1 production, as a biosynthetic gene cluster. These include kk1B, which encodes nonribosomal peptide synthetase with a domain structure that is consistent with the structural features of KK-1, and kk1F, which encodes a transcription factor. The overexpression of kk1F increased the expression of the entire cluster genes and, consequently, improved KK-1 production, whereas its deletion decreased the expression of the entire cluster genes and almost eliminated KK-1 production, demonstrating that the protein encoded by kk1F regulates the expressions of the other nine cluster genes cooperatively as the pathway-specific transcription factor. Furthermore, the deletion of each cluster gene caused a reduction in KK-1 productivity, indicating that each gene is involved in KK-1 production. The genes kk1A, kk1D, kk1H, and kk1I, which showed a significant decrease in KK-1 productivity due to deletion, were presumed to be directly involved in KK-1 structure formation, including the biosynthesis of the constituent residues. kk1C, kk1E, kk1G, and kk1J, which maintained a certain level of KK-1 productivity despite deletion, were possibly involved in promoting or assisting KK-1 production, such as extracellular transportation and the removal of aberrant units incorporated into the peptide chain.
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Affiliation(s)
- Shigenari Yamaguchi
- Biotechnology Laboratory, Life & Environment Research Center, Life Science Research Institute, Research & Development Division, Kumiai Chemical Industry Co., Ltd., Shizuoka, Japan
| | - Tomonori Fujioka
- Biotechnology Laboratory, Life & Environment Research Center, Life Science Research Institute, Research & Development Division, Kumiai Chemical Industry Co., Ltd., Shizuoka, Japan
| | - Akira Yoshimi
- ABE-Project, New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan
- Laboratory of Terrestrial Microbial Ecology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | | | - Maiko Umemura
- Bio-system Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Keietsu Abe
- ABE-Project, New Industry Creation Hatchery Center, Tohoku University, Sendai, Japan
- Laboratory of Applied Microbiology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Masayuki Machida
- Bio-system Research Group, Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
- Graduate School of Engineering, Genome Biotechnology Laboratory, Kanazawa Institute of Technology, Ishikawa, Japan
| | - Kiyoshi Kawai
- Biotechnology Laboratory, Life & Environment Research Center, Life Science Research Institute, Research & Development Division, Kumiai Chemical Industry Co., Ltd., Shizuoka, Japan
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Loi M, Logrieco AF, Pusztahelyi T, Leiter É, Hornok L, Pócsi I. Advanced mycotoxin control and decontamination techniques in view of an increased aflatoxin risk in Europe due to climate change. Front Microbiol 2023; 13:1085891. [PMID: 36762096 PMCID: PMC9907446 DOI: 10.3389/fmicb.2022.1085891] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Aflatoxins are toxic secondary metabolites produced by Aspergillus spp. found in staple food and feed commodities worldwide. Aflatoxins are carcinogenic, teratogenic, and mutagenic, and pose a serious threat to the health of both humans and animals. The global economy and trade are significantly affected as well. Various models and datasets related to aflatoxins in maize have been developed and used but have not yet been linked. The prevention of crop loss due to aflatoxin contamination is complex and challenging. Hence, the set-up of advanced decontamination is crucial to cope with the challenge of climate change, growing population, unstable political scenarios, and food security problems also in European countries. After harvest, decontamination methods can be applied during transport, storage, or processing, but their application for aflatoxin reduction is still limited. Therefore, this review aims to investigate the effects of environmental factors on aflatoxin production because of climate change and to critically discuss the present-day and novel decontamination techniques to unravel gaps and limitations to propose them as a tool to tackle an increased aflatoxin risk in Europe.
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Affiliation(s)
- Martina Loi
- Institute of Sciences of Food Production, National Research Council, Bari, Italy,*Correspondence: Martina Loi, ✉
| | - Antonio F. Logrieco
- Institute of Sciences of Food Production, National Research Council, Bari, Italy
| | - Tünde Pusztahelyi
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
| | - Éva Leiter
- Department of Molecular Biotechnology and Microbiology, Faculty of Science and Technology, Institute of Biotechnology, University of Debrecen, Debrecen, Hungary,ELRN-UD Fungal Stress Biology Research Group, University of Debrecen, Debrecen, Hungary
| | - László Hornok
- Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Faculty of Science and Technology, Institute of Biotechnology, University of Debrecen, Debrecen, Hungary,ELRN-UD Fungal Stress Biology Research Group, University of Debrecen, Debrecen, Hungary
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Wang W, Liang X, Li Y, Wang P, Keller NP. Genetic Regulation of Mycotoxin Biosynthesis. J Fungi (Basel) 2022; 9:jof9010021. [PMID: 36675842 PMCID: PMC9861139 DOI: 10.3390/jof9010021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/20/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Mycotoxin contamination in food poses health hazards to humans. Current methods of controlling mycotoxins still have limitations and more effective approaches are needed. During the past decades of years, variable environmental factors have been tested for their influence on mycotoxin production leading to elucidation of a complex regulatory network involved in mycotoxin biosynthesis. These regulators are putative targets for screening molecules that could inhibit mycotoxin synthesis. Here, we summarize the regulatory mechanisms of hierarchical regulators, including pathway-specific regulators, global regulators and epigenetic regulators, on the production of the most critical mycotoxins (aflatoxins, patulin, citrinin, trichothecenes and fumonisins). Future studies on regulation of mycotoxins will provide valuable knowledge for exploring novel methods to inhibit mycotoxin biosynthesis in a more efficient way.
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Affiliation(s)
- Wenjie Wang
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
- Correspondence: (W.W.); (N.P.K.)
| | - Xinle Liang
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Yudong Li
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Pinmei Wang
- Ocean College, Zhejiang University, Zhoushan 316021, China
| | - Nancy P. Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Correspondence: (W.W.); (N.P.K.)
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Mahata PK, Dass RS, Gunti L, Thorat PA. First report on the metabolic characterization of Sterigmatocystin production by select Aspergillus species from the Nidulantes section in Foeniculum vulgare. Front Microbiol 2022; 13:958424. [PMID: 36090109 PMCID: PMC9459157 DOI: 10.3389/fmicb.2022.958424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/03/2022] [Indexed: 12/16/2022] Open
Abstract
Spices are typically grown in climates that support the growth of toxigenic fungi and the production of mycotoxins. The Aspergilli described in this study, as well as the sterigmatocystin (STC) detected, are causes for concern due to their potential to induce food poisoning. One of the most well-known producers of the carcinogenic STC is Aspergillus nidulans. This research explores the occurrence of STC-producing fungi in Foeniculum vulgare, a spice that is marketed in India and other parts of the world. This innovative study details the mycotoxigenic potential of five Aspergilli belonging to Section Nidulantes, namely Aspergillus latus (02 isolates), Emericella quadrilineata (02 isolates), and Aspergillus nidulans (01 isolate), with respect to STC contamination. These five isolates of Aspergilli were screened to produce STC on yeast extract sucrose (YES) medium in a controlled environment with regard to light, temperature, pH, and humidity, among other variables. The expression patterns of regulatory genes, namely, aflR, laeA, pacC, fluG, flbA, pksA, and mtfA were studied on the Czapek–Dox agar (CDA) medium. STC biosynthesis by the test isolates was done in potato dextrose broth (PDB) under optimum conditions, followed by the extraction and purification of the broth using ethyl acetate. High-performance liquid chromatography (HPLC) with an ultraviolet (UV) detector was utilized to detect compounds in eluted samples. F. vulgare contains Aspergilli that have been shown to have mycotoxigenic potential, which can accumulate in the spice during its active growth and thereby cause the elaboration of mycotoxins.
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Motoyama T, Yun CS, Osada H. Biosynthesis and biological function of secondary metabolites of the rice blast fungus Pyricularia oryzae. J Ind Microbiol Biotechnol 2021; 48:kuab058. [PMID: 34379774 PMCID: PMC8788799 DOI: 10.1093/jimb/kuab058] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 08/05/2021] [Indexed: 11/18/2022]
Abstract
Filamentous fungi have many secondary metabolism genes and produce a wide variety of secondary metabolites with complex and unique structures. However, the role of most secondary metabolites remains unclear. Moreover, most fungal secondary metabolism genes are silent or poorly expressed under laboratory conditions and are difficult to utilize. Pyricularia oryzae, the causal pathogen of rice blast disease, is a well-characterized plant pathogenic fungus. P. oryzae also has a large number of secondary metabolism genes and appears to be a suitable organism for analyzing secondary metabolites. However, in case of this fungus, biosynthetic genes for only four groups of secondary metabolites have been well characterized. Among two of the four groups of secondary metabolites, biosynthetic genes were identified by activating secondary metabolism. These secondary metabolites include melanin, a polyketide compound required for rice infection; tenuazonic acid, a well-known mycotoxin produced by various plant pathogenic fungi and biosynthesized by a unique nonribosomal peptide synthetase-polyketide synthase hybrid enzyme; nectriapyrones, antibacterial polyketide compounds produced mainly by symbiotic fungi, including plant pathogens and endophytes, and pyriculols, phytotoxic polyketide compounds. This review mainly focuses on the biosynthesis and biological functions of the four groups of P. oryzae secondary metabolites.
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Affiliation(s)
- Takayuki Motoyama
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Choong-Soo Yun
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Hiroyuki Osada
- Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
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Wang W, Yu Y, Keller NP, Wang P. Presence, Mode of Action, and Application of Pathway Specific Transcription Factors in Aspergillus Biosynthetic Gene Clusters. Int J Mol Sci 2021; 22:ijms22168709. [PMID: 34445420 PMCID: PMC8395729 DOI: 10.3390/ijms22168709] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/10/2021] [Accepted: 08/10/2021] [Indexed: 01/21/2023] Open
Abstract
Fungal secondary metabolites are renowned toxins as well as valuable sources of antibiotics, cholesterol-lowering drugs, and immunosuppressants; hence, great efforts were levied to understand how these compounds are genetically regulated. The genes encoding for the enzymes required for synthesizing secondary metabolites are arranged in biosynthetic gene clusters (BGCs). Often, BGCs contain a pathway specific transcription factor (PSTF), a valuable tool in shutting down or turning up production of the BGC product. In this review, we present an in-depth view of PSTFs by examining over 40 characterized BGCs in the well-studied fungal species Aspergillus nidulans and Aspergillus fumigatus. Herein, we find BGC size is a predictor for presence of PSTFs, consider the number and the relative location of PSTF in regard to the cluster(s) regulated, discuss the function and the evolution of PSTFs, and present application strategies for pathway specific activation of cryptic BGCs.
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Affiliation(s)
- Wenjie Wang
- Ocean College, Zhejiang University, Zhoushan 316021, China; (W.W.); (Y.Y.)
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yuchao Yu
- Ocean College, Zhejiang University, Zhoushan 316021, China; (W.W.); (Y.Y.)
| | - Nancy P. Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
- Correspondence: (N.P.K.); (P.W.)
| | - Pinmei Wang
- Ocean College, Zhejiang University, Zhoushan 316021, China; (W.W.); (Y.Y.)
- Correspondence: (N.P.K.); (P.W.)
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Alam B, Lǐ J, Gě Q, Khan MA, Gōng J, Mehmood S, Yuán Y, Gǒng W. Endophytic Fungi: From Symbiosis to Secondary Metabolite Communications or Vice Versa? FRONTIERS IN PLANT SCIENCE 2021; 12:791033. [PMID: 34975976 PMCID: PMC8718612 DOI: 10.3389/fpls.2021.791033] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/29/2021] [Indexed: 05/08/2023]
Abstract
Endophytic fungi (EF) are a group of fascinating host-associated fungal communities that colonize the intercellular or intracellular spaces of host tissues, providing beneficial effects to their hosts while gaining advantages. In recent decades, accumulated research on endophytic fungi has revealed their biodiversity, wide-ranging ecological distribution, and multidimensional interactions with host plants and other microbiomes in the symbiotic continuum. In this review, we highlight the role of secondary metabolites (SMs) as effectors in these multidimensional interactions, and the biosynthesis of SMs in symbiosis via complex gene expression regulation mechanisms in the symbiotic continuum and via the mimicry or alteration of phytochemical production in host plants. Alternative biological applications of SMs in modern medicine, agriculture, and industry and their major classes are also discussed. This review recapitulates an introduction to the research background, progress, and prospects of endophytic biology, and discusses problems and substantive challenges that need further study.
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Affiliation(s)
- Beena Alam
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Jùnwén Lǐ
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Qún Gě
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Mueen Alam Khan
- Department of Plant Breeding & Genetics, University College of Agriculture and Environmental Sciences, The Islamia University of Bahawalpur (IUB), Bahawalpur, Pakistan
| | - Jǔwǔ Gōng
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Shahid Mehmood
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yǒulù Yuán
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- *Correspondence: Wànkuí Gǒng,
| | - Wànkuí Gǒng
- State Key Laboratory of Cotton Biology, Key Laboratory of Biological and Genetic Breeding of Cotton, The Ministry of Agriculture, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Yǒulù Yuán,
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El Hajj Assaf C, Zetina-Serrano C, Tahtah N, Khoury AE, Atoui A, Oswald IP, Puel O, Lorber S. Regulation of Secondary Metabolism in the Penicillium Genus. Int J Mol Sci 2020; 21:E9462. [PMID: 33322713 PMCID: PMC7763326 DOI: 10.3390/ijms21249462] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/03/2020] [Accepted: 12/08/2020] [Indexed: 12/13/2022] Open
Abstract
Penicillium, one of the most common fungi occurring in a diverse range of habitats, has a worldwide distribution and a large economic impact on human health. Hundreds of the species belonging to this genus cause disastrous decay in food crops and are able to produce a varied range of secondary metabolites, from which we can distinguish harmful mycotoxins. Some Penicillium species are considered to be important producers of patulin and ochratoxin A, two well-known mycotoxins. The production of these mycotoxins and other secondary metabolites is controlled and regulated by different mechanisms. The aim of this review is to highlight the different levels of regulation of secondary metabolites in the Penicillium genus.
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Affiliation(s)
- Christelle El Hajj Assaf
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
- Institute for Agricultural and Fisheries Research (ILVO), member of Food2Know, Brusselsesteenweg 370, 9090 Melle, Belgium
| | - Chrystian Zetina-Serrano
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
| | - Nadia Tahtah
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
- Centre D’analyse et de Recherche, Unité de Recherche Technologies et Valorisations Agro-Alimentaires, Faculté des Sciences, Université Saint-Joseph, P.O. Box 17-5208, Mar Mikhael, Beirut 1104, Lebanon;
| | - André El Khoury
- Centre D’analyse et de Recherche, Unité de Recherche Technologies et Valorisations Agro-Alimentaires, Faculté des Sciences, Université Saint-Joseph, P.O. Box 17-5208, Mar Mikhael, Beirut 1104, Lebanon;
| | - Ali Atoui
- Laboratory of Microbiology, Department of Life and Earth Sciences, Faculty of Sciences I, Lebanese University, Hadath Campus, P.O. Box 5, Beirut 1104, Lebanon;
| | - Isabelle P. Oswald
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
| | - Olivier Puel
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
| | - Sophie Lorber
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, 31027 Toulouse, France; (C.E.H.A.); (C.Z.-S.); (N.T.); (I.P.O.); (S.L.)
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12
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Secondary Metabolites of the Rice Blast Fungus Pyricularia oryzae: Biosynthesis and Biological Function. Int J Mol Sci 2020; 21:ijms21228698. [PMID: 33218033 PMCID: PMC7698770 DOI: 10.3390/ijms21228698] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 02/07/2023] Open
Abstract
Plant pathogenic fungi produce a wide variety of secondary metabolites with unique and complex structures. However, most fungal secondary metabolism genes are poorly expressed under laboratory conditions. Moreover, the relationship between pathogenicity and secondary metabolites remains unclear. To activate silent gene clusters in fungi, successful approaches such as epigenetic control, promoter exchange, and heterologous expression have been reported. Pyricularia oryzae, a well-characterized plant pathogenic fungus, is the causal pathogen of rice blast disease. P. oryzae is also rich in secondary metabolism genes. However, biosynthetic genes for only four groups of secondary metabolites have been well characterized in this fungus. Biosynthetic genes for two of the four groups of secondary metabolites have been identified by activating secondary metabolism. This review focuses on the biosynthesis and roles of the four groups of secondary metabolites produced by P. oryzae. These secondary metabolites include melanin, a polyketide compound required for rice infection; pyriculols, phytotoxic polyketide compounds; nectriapyrones, antibacterial polyketide compounds produced mainly by symbiotic fungi including endophytes and plant pathogens; and tenuazonic acid, a well-known mycotoxin produced by various plant pathogenic fungi and biosynthesized by a unique NRPS-PKS enzyme.
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13
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Jun SC, Kim JH, Han KH. The Conserved MAP Kinase MpkB Regulates Development and Sporulation without Affecting Aflatoxin Biosynthesis in Aspergillus flavus. J Fungi (Basel) 2020; 6:jof6040289. [PMID: 33207581 PMCID: PMC7711526 DOI: 10.3390/jof6040289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/20/2022] Open
Abstract
In eukaryotes, the MAP kinase signaling pathway plays pivotal roles in regulating the expression of genes required for growth, development, and stress response. Here, we deleted the mpkB gene (AFLA_034170), an ortholog of the Saccharomyces cerevisiae FUS3 gene, to characterize its function in Aspergillus flavus, a cosmopolitan, pathogenic, and aflatoxin-producing fungus. Previous studies revealed that MpkB positively regulates sexual and asexual differentiation in Aspergillus nidulans. In A. flavus, mpkB deletion resulted in an approximately 60% reduction in conidia production compared to the wild type without mycelial growth defects. Moreover, the mutant produced immature and abnormal conidiophores exhibiting vesicular dome-immaturity in the conidiophore head, decreased phialide numbers, and very short stalks. Interestingly, the ΔmpkB mutant could not produce sclerotia but produced aflatoxin B1 normally. Taken together, these results suggest that the A. flavus MpkB MAP kinase positively regulates conidiation and sclerotia formation but is not involved in the production of secondary metabolites such as aflatoxin B1.
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Affiliation(s)
| | - Jong-Hwa Kim
- Correspondence: (J.-H.K.); (K.-H.H.); Tel.: +82-63-290-1439 (J.-H.K.); +82-63-290-1427 (K.-H.H.)
| | - Kap-Hoon Han
- Correspondence: (J.-H.K.); (K.-H.H.); Tel.: +82-63-290-1439 (J.-H.K.); +82-63-290-1427 (K.-H.H.)
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14
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Kong Q, Chang PK, Li C, Hu Z, Zheng M, Sun Q, Shan S. Identification of AflR Binding Sites in the Genome of Aspergillus flavus by ChIP-Seq. J Fungi (Basel) 2020; 6:jof6020052. [PMID: 32326370 PMCID: PMC7344883 DOI: 10.3390/jof6020052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/20/2020] [Accepted: 04/20/2020] [Indexed: 11/16/2022] Open
Abstract
We report here the AflR binding motif of Aspergillus flavus for the first time with the aid of ChIP-seq analysis. Of the 540 peak sequences associated with AflR binding events, 66.8% were located within 2 kb upstream (promoter region) of translational start sites. The identified 18-bp binding motif was a perfect palindromic sequence, 5′-CSSGGGWTCGAWCCCSSG’3′ with S representing G or C and W representing A or T. On closer examination, we hypothesized that the 18-bp motif sequence identified contained two identical parts (here called motif A and motif B). Motif A was in positions 8–18 on the upper strand, while motif B was in positions 11-1 on the bottom strand. The inferred length and sequence of the putative motif identified in A. flavus were similar to previous findings in A. parasiticus and A. nidulans. Gene ontology analysis indicated that AflR bound to other genes outside the aflatoxin biosynthetic gene cluster.
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Affiliation(s)
- Qing Kong
- School of Food Science and Engineering, Ocean University of China, Qingdao 266003, China;
| | - Perng-Kuang Chang
- Southern Regional Research Center, Agricultural Research Service, US Department of Agriculture, New Orleans, LA 70124, USA;
| | - Chunjuan Li
- Shandong Peanut Research Institute, Qingdao 266110, China; (C.L.); (Q.S.)
| | - Zhaorong Hu
- State Key Laboratory for Agrobiotechnology and Key Laboratory of Crop Heterosis and Utilization (MOE), Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China; (Z.H.); (M.Z.)
| | - Mei Zheng
- State Key Laboratory for Agrobiotechnology and Key Laboratory of Crop Heterosis and Utilization (MOE), Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China; (Z.H.); (M.Z.)
| | - Quanxi Sun
- Shandong Peanut Research Institute, Qingdao 266110, China; (C.L.); (Q.S.)
| | - Shihua Shan
- Shandong Peanut Research Institute, Qingdao 266110, China; (C.L.); (Q.S.)
- Correspondence: ; Tel.: +86-532-8762-9307
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15
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Aflatoxin Biosynthesis and Genetic Regulation: A Review. Toxins (Basel) 2020; 12:toxins12030150. [PMID: 32121226 PMCID: PMC7150809 DOI: 10.3390/toxins12030150] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/27/2020] [Accepted: 02/25/2020] [Indexed: 12/15/2022] Open
Abstract
The study of fungal species evolved radically with the development of molecular techniques and produced new evidence to understand specific fungal mechanisms such as the production of toxic secondary metabolites. Taking advantage of these technologies to improve food safety, the molecular study of toxinogenic species can help elucidate the mechanisms underlying toxin production and enable the development of new effective strategies to control fungal toxicity. Numerous studies have been made on genes involved in aflatoxin B1 (AFB1) production, one of the most hazardous carcinogenic toxins for humans and animals. The current review presents the roles of these different genes and their possible impact on AFB1 production. We focus on the toxinogenic strains Aspergillus flavus and A. parasiticus, primary contaminants and major producers of AFB1 in crops. However, genetic reports on A. nidulans are also included because of the capacity of this fungus to produce sterigmatocystin, the penultimate stable metabolite during AFB1 production. The aim of this review is to provide a general overview of the AFB1 enzymatic biosynthesis pathway and its link with the genes belonging to the AFB1 cluster. It also aims to illustrate the role of global environmental factors on aflatoxin production and the recent data that demonstrate an interconnection between genes regulated by these environmental signals and aflatoxin biosynthetic pathway.
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16
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Son YE, Cho HJ, Lee MK, Park HS. Characterizing the role of Zn cluster family transcription factor ZcfA in governing development in two Aspergillus species. PLoS One 2020; 15:e0228643. [PMID: 32017793 PMCID: PMC6999877 DOI: 10.1371/journal.pone.0228643] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/20/2020] [Indexed: 01/08/2023] Open
Abstract
Filamentous fungi reproduce asexually or sexually, and the processes of asexual and sexual development are tightly regulated by a variety of transcription factors. In this study, we characterized a Zn2Cys6 transcription factor in two Aspergillus species, A. nidulans (AN5859) and A. flavus (AFLA_046870). AN5859 encodes a Zn2Cys6 transcription factor, called ZcfA. In A. nidulans, ΔzcfA mutants exhibit decreased fungal growth, a reduction in cleistothecia production, and increased asexual reproduction. Overexpression of zcfA results in increased conidial production, suggesting that ZcfA is required for proper asexual and sexual development in A. nidulans. In conidia, deletion of zcfA causes decreased trehalose levels and decreased spore viability but increased thermal sensitivity. In A. flavus, the deletion of the zcfA homolog AFLA_046870 causes increased conidial production but decreased sclerotia production; these effects are similar to those of zcfA deletion in A. nidulans development. Overall, these results demonstrate that ZcfA is essential for maintaining a balance between asexual and sexual development and that some roles of ZcfA are conserved in Aspergillus spp.
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Affiliation(s)
- Ye-Eun Son
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - He-Jin Cho
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
| | - Mi-Kyung Lee
- Biological Resource Center (BRC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup-si, Republic of Korea
| | - Hee-Soo Park
- School of Food Science and Biotechnology, Kyungpook National University, Daegu, Republic of Korea
- Department of Integrative Biology, Kyungpook National University, Daegu, Republic of Korea
- * E-mail:
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17
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Kumar A, Arora S, Jain KK, Sharma KK. Metabolic coupling in the co-cultured fungal-yeast suite of Trametes ljubarskyi and Rhodotorula mucilaginosa leads to hypersecretion of laccase isozymes. Fungal Biol 2019; 123:913-926. [DOI: 10.1016/j.funbio.2019.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 09/25/2019] [Accepted: 09/30/2019] [Indexed: 12/12/2022]
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18
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Hanano A, Almousally I, Shaban M. Exposure of Aspergillus flavus NRRL 3357 to the Environmental Toxin, 2,3,7,8-Tetrachlorinated Dibenzo- p-Dioxin, Results in a Hyper Aflatoxicogenic Phenotype: A Possible Role for Caleosin/Peroxygenase (AfPXG). Front Microbiol 2019; 10:2338. [PMID: 31681203 PMCID: PMC6803392 DOI: 10.3389/fmicb.2019.02338] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 09/25/2019] [Indexed: 12/19/2022] Open
Abstract
Aflatoxins (AFs) as potent food contaminants are highly detrimental to human and animal health. The production of such biological toxins is influenced by environmental factors including pollutants, such as dioxins. Here, we report the biological feedback of an active AF-producer strain of A. flavus upon in vitro exposure to the most toxic congener of dioxins, the 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD). The phenotype of TCDD-exposed A. flavus was typified by a severe limitation in vegetative growth, activation of conidia formation and a significant boost in AF production. Furthermore, the level of reactive oxygen species (ROS) in fungal protoplast was increased (3.1- to 3.8-fold) in response to TCDD exposure at 10 and 50 ng mL-1, respectively. In parallel, superoxide dismutase (SOD) and catalase (CAT) activities were, respectively, increased by a factor of 2 and 3. In contrast to controls, transcript, protein and enzymatic activity of caleosin/peroxygenase (AfPXG) was also significantly induced in TCDD-exposed fungi. Subsequently, fungal cells accumulated fivefold more lipid droplets (LDs) than controls. Moreover, the TCDD-exposed fungi exhibited twofold higher levels of AFB1. Interestingly, TCDD-induced hyperaflatoxicogenicity was drastically abolished in the AfPXG-silencing strain of A. flavus, suggesting a role for AfPXG in fungal response to TCDD. Finally, TCDD-exposed fungi showed an increased in vitro virulence in terms of sporulation and AF production. The data highlight the possible effects of dioxin on aflatoxicogenicity of A. flavus and suggest therefore that attention should be paid in particular to the potential consequences of climate change on global food safety.
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Affiliation(s)
- Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria, Damascus, Syria
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19
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Collemare J, Seidl MF. Chromatin-dependent regulation of secondary metabolite biosynthesis in fungi: is the picture complete? FEMS Microbiol Rev 2019; 43:591-607. [PMID: 31301226 PMCID: PMC8038932 DOI: 10.1093/femsre/fuz018] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 06/18/2019] [Indexed: 01/07/2023] Open
Abstract
Fungal secondary metabolites are small molecules that exhibit diverse biological activities exploited in medicine, industry and agriculture. Their biosynthesis is governed by co-expressed genes that often co-localize in gene clusters. Most of these secondary metabolite gene clusters are inactive under laboratory conditions, which is due to a tight transcriptional regulation. Modifications of chromatin, the complex of DNA and histone proteins influencing DNA accessibility, play an important role in this regulation. However, tinkering with well-characterised chemical and genetic modifications that affect chromatin alters the expression of only few biosynthetic gene clusters, and thus the regulation of the vast majority of biosynthetic pathways remains enigmatic. In the past, attempts to activate silent gene clusters in fungi mainly focused on histone acetylation and methylation, while in other eukaryotes many other post-translational modifications are involved in transcription regulation. Thus, how chromatin regulates the expression of gene clusters remains a largely unexplored research field. In this review, we argue that focusing on only few well-characterised chromatin modifications is significantly hampering our understanding of the chromatin-based regulation of biosynthetic gene clusters. Research on underexplored chromatin modifications and on the interplay between different modifications is timely to fully explore the largely untapped reservoir of fungal secondary metabolites.
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Affiliation(s)
| | - Michael F Seidl
- Corresponding author: Theoretical Biology and Bioinformatics, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands. E-mail: ; Present address: Theoretical Biology and Bioinformatics, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
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20
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Hua SST, Parfitt DE, Sarreal SBL, Sidhu G. Dual culture of atoxigenic and toxigenic strains of Aspergillus flavus to gain insight into repression of aflatoxin biosynthesis and fungal interaction. Mycotoxin Res 2019; 35:381-389. [PMID: 31161589 DOI: 10.1007/s12550-019-00364-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/27/2019] [Accepted: 05/06/2019] [Indexed: 11/24/2022]
Abstract
Application of atoxigenic strains to compete against toxigenic strains of Aspergillus flavus strains has emerged as one of the practical strategies for reducing aflatoxin contamination in corn, peanut, and tree nuts. The actual mechanism that results in aflatoxin reduction is not fully understood. Real-time RT-PCR and relative quantification of gene expression protocol were applied to elucidate the molecular mechanism. Transcriptional analyses of aflatoxin biosynthetic gene cluster in dual culture of toxigenic and atoxigenic A. flavus strains were carried out. Six targeted genes, aflR, aflJ, omtA, ordA, pksA, and vbs, were downregulated to variable levels depending on paired strains of toxigenic and atoxigenic A. flavus. Consistent with the decreased gene expression levels, the aflatoxin concentrations in dual cultures were reduced significantly in comparison with toxigenic cultures. Fluorescent images showed fungal hyphae in dual culture displayed green fluorescent, and contacts of live hyphae were seen. A coconut agar plate assay was used to show that toxigenic A. flavus colony produced blue fluorescence under long UV exposure, suggesting that aflatoxin is exported outside fungal hyphae. Furthermore, the assay was applied to demonstrate the potential role of thigmo-regulation in fungal interaction.
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Affiliation(s)
- Sui Sheng T Hua
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA.
| | - Dan E Parfitt
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Siov Bouy L Sarreal
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA
| | - Gaganjot Sidhu
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA
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21
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Chen Y, Kong Q, Liang Y. Three newly identified peptides from Bacillus megaterium strongly inhibit the growth and aflatoxin B1 production of Aspergillus flavus. Food Control 2019. [DOI: 10.1016/j.foodcont.2018.07.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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22
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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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23
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Espindola AS, Schneider W, Cardwell KF, Carrillo Y, Hoyt PR, Marek SM, Melouk HA, Garzon CD. Inferring the presence of aflatoxin-producing Aspergillus flavus strains using RNA sequencing and electronic probes as a transcriptomic screening tool. PLoS One 2018; 13:e0198575. [PMID: 30325975 PMCID: PMC6191106 DOI: 10.1371/journal.pone.0198575] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/26/2018] [Indexed: 11/24/2022] Open
Abstract
E-probe Diagnostic for Nucleic acid Analysis (EDNA) is a bioinformatic tool originally developed to detect plant pathogens in metagenomic databases. However, enhancements made to EDNA increased its capacity to conduct hypothesis directed detection of specific gene targets present in transcriptomic databases. To target specific pathogenicity factors used by the pathogen to infect its host or other targets of interest, e-probes need to be developed for transcripts related to that function. In this study, EDNA transcriptomics (EDNAtran) was developed to detect the expression of genes related to aflatoxin production at the transcriptomic level. E-probes were designed from genes up-regulated during A. flavus aflatoxin production. EDNAtran detected gene transcripts related to aflatoxin production in a transcriptomic database from corn, where aflatoxin was produced. The results were significantly different from e-probes being used in the transcriptomic database where aflatoxin was not produced (atoxigenic AF36 strain and toxigenic AF70 in Potato Dextrose Broth).
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Affiliation(s)
- Andres S. Espindola
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
- National Institute for Microbial Forensics and Food and Agricultural Biosecurity (NIMFFAB), Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - William Schneider
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Kitty F. Cardwell
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
- National Institute for Microbial Forensics and Food and Agricultural Biosecurity (NIMFFAB), Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Yisel Carrillo
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Peter R. Hoyt
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Stephen M. Marek
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Hassan A. Melouk
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Carla D. Garzon
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
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Hu Y, Yang G, Zhang D, Liu Y, Li Y, Lin G, Guo Z, Wang S, Zhuang Z. The PHD Transcription Factor Rum1 Regulates Morphogenesis and Aflatoxin Biosynthesis in Aspergillus flavus. Toxins (Basel) 2018; 10:toxins10070301. [PMID: 30036940 PMCID: PMC6070901 DOI: 10.3390/toxins10070301] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 07/16/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023] Open
Abstract
Aspergillus flavus produces mycotoxins especially aflatoxin B1 and infects crops worldwide. As a PHD transcription factor, there is no report on the role of Rum1 in the virulence of Aspergillus spp. yet. This study explored the biological function of Rum1 in A. flavus through the construction of rum1 deletion mutants and rum1 complementation strains with the method of homologous recombination. It was found, in the study, that Rum1 negatively regulates conidiation through abaA and brlA, positively regulates sclerotia formation through nsdC, nsdD, and sclR, triggers aflatoxin biological synthesis, and enhances the activity of amylase. Our findings suggested that Rum1 plays a major role in the growth of mycelia, conidia, and sclerotia production along with aflatoxin biosynthesis in A. flavus.
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Affiliation(s)
- Yule Hu
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Guang Yang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Danping Zhang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Yaju Liu
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Yu Li
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
- Xiamen Genokon Medical Genokon Company, Xiamen 361115, China.
| | - Guanglan Lin
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhiqiang Guo
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Shihua Wang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
| | - Zhenhong Zhuang
- Fujian Key Laboratory of Pathogenic Fungi and Mycotoxins, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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25
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Ámon J, Keisham K, Bokor E, Kelemen E, Vágvölgyi C, Hamari Z. Sterigmatocystin production is restricted to hyphae located in the proximity of hülle cells. J Basic Microbiol 2018; 58:590-596. [PMID: 29733450 DOI: 10.1002/jobm.201800020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/19/2018] [Accepted: 04/22/2018] [Indexed: 12/20/2022]
Abstract
Aspergillus nidulans produces sterigmatocystin, a secondary metabolite mycotoxin, for the protection of its reproductive structures. Previous studies on grazing behavior of fungivore arthropods, regulation of sexual development, and secondary metabolite biosynthesis have revealed the association of sterigmatocystin biosynthesis with sexual reproduction, but the spatial distribution of sterigmatocystin producing hyphae within the colony has never been investigated. In this work, we aimed to locate the site of sterigmatocystin production within the colony by employing a yCFP reporter system. We demonstrated that the stcO promoter is active only in vegetative hyphae that surround groups of hülle cells and the activity decreases and eventually ceases as the distance between the hypha and the hülle cells increases. This phenomenon indicates that the vegetative mycelium might consist of morphologically uniform, but functionally different hyphae.
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Affiliation(s)
- Judit Ámon
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Kabichandra Keisham
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Eszter Bokor
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Evelyn Kelemen
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Csaba Vágvölgyi
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
| | - Zsuzsanna Hamari
- Faculty of Science and Informatics, Department of Microbiology, University of Szeged, Szeged, Hungary
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Aspergillus flavus Secondary Metabolites: More than Just Aflatoxins. Food Saf (Tokyo) 2018; 6:7-32. [PMID: 32231944 DOI: 10.14252/foodsafetyfscj.2017024] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/09/2018] [Indexed: 11/21/2022] Open
Abstract
Aspergillus flavus is best known for producing the family of potent carcinogenic secondary metabolites known as aflatoxins. However, this opportunistic plant and animal pathogen also produces numerous other secondary metabolites, many of which have also been shown to be toxic. While about forty of these secondary metabolites have been identified from A. flavus cultures, analysis of the genome has predicted the existence of at least 56 secondary metabolite gene clusters. Many of these gene clusters are not expressed during growth of the fungus on standard laboratory media. This presents researchers with a major challenge of devising novel strategies to manipulate the fungus and its genome so as to activate secondary metabolite gene expression and allow identification of associated cluster metabolites. In this review, we discuss the genetic, biochemical and bioinformatic methods that are being used to identify previously uncharacterized secondary metabolite gene clusters and their associated metabolites. It is important to identify as many of these compounds as possible to determine their bioactivity with respect to fungal development, survival, virulence and especially with respect to any potential synergistic toxic effects with aflatoxin.
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Wiemann P, Soukup AA, Folz JS, Wang PM, Noack A, Keller NP. CoIN: co-inducible nitrate expression system for secondary metabolites in Aspergillus nidulans. Fungal Biol Biotechnol 2018; 5:6. [PMID: 29564145 PMCID: PMC5851313 DOI: 10.1186/s40694-018-0049-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/05/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sequencing of fungal species has demonstrated the existence of thousands of putative secondary metabolite gene clusters, the majority of them harboring a unique set of genes thought to participate in production of distinct small molecules. Despite the ready identification of key enzymes and potential cluster genes by bioinformatics techniques in sequenced genomes, the expression and identification of fungal secondary metabolites in the native host is often hampered as the genes might not be expressed under laboratory conditions and the species might not be amenable to genetic manipulation. To overcome these restrictions, we developed an inducible expression system in the genetic model Aspergillus nidulans. RESULTS We genetically engineered a strain of A. nidulans devoid of producing eight of the most abundant endogenous secondary metabolites to express the sterigmatocystin Zn(II)2Cys6 transcription factor-encoding gene aflR and its cofactor aflS under control of the nitrate inducible niiA/niaD promoter. Furthermore, we identified a subset of promoters from the sterigmatocystin gene cluster that are under nitrate-inducible AflR/S control in our production strain in order to yield coordinated expression without the risks from reusing a single inducible promoter. As proof of concept, we used this system to produce β-carotene from the carotenoid gene cluster of Fusarium fujikuroi. CONCLUSION Utilizing one-step yeast recombinational cloning, we developed an inducible expression system in the genetic model A. nidulans and show that it can be successfully used to produce commercially valuable metabolites.
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Affiliation(s)
- Philipp Wiemann
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
- Present Address: Hexagon Bio, Menlo Park, CA 94025 USA
| | - Alexandra A. Soukup
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
- Present Address: Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53705 USA
| | - Jacob S. Folz
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
- Present Address: Davis Genome Center – Metabolomics, University of California, 451 Health Science Drive, Davis, CA 95616 USA
| | - Pin-Mei Wang
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
- Present Address: Ocean College, Zhejiang University, Hangzhou, 310058 Zhejiang Province People’s Republic of China
| | - Andreas Noack
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
| | - Nancy P. Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706 USA
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706 USA
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Le THT, Oki A, Goto M, Shimizu K. Protein O-mannosyltransferases are required for sterigmatocystin production and developmental processes in Aspergillus nidulans. Curr Genet 2018; 64:1043-1056. [DOI: 10.1007/s00294-018-0816-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/19/2022]
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Bhatnagar D, Rajasekaran K, Gilbert M, Cary J, Magan N. Advances in molecular and genomic research to safeguard food and feed supply from aflatoxin contamination. WORLD MYCOTOXIN J 2018. [DOI: 10.3920/wmj2017.2283] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Worldwide recognition that aflatoxin contamination of agricultural commodities by the fungus Aspergillus flavus is a global problem has significantly benefitted from global collaboration for understanding the contaminating fungus, as well as for developing and implementing solutions against the contamination. The effort to address this serious food and feed safety issue has led to a detailed understanding of the taxonomy, ecology, physiology, genomics and evolution of A. flavus, as well as strategies to reduce or control pre-harvest aflatoxin contamination, including (1) biological control, using atoxigenic aspergilli, (2) proteomic and genomic analyses for identifying resistance factors in maize as potential breeding markers to enable development of resistant maize lines, and (3) enhancing host-resistance by bioengineering of susceptible crops, such as cotton, maize, peanut and tree nuts. A post-harvest measure to prevent the occurrence of aflatoxin contamination in storage is also an important component for reducing exposure of populations worldwide to aflatoxins in food and feed supplies. The effect of environmental changes on aflatoxin contamination levels has recently become an important aspect for study to anticipate future contamination levels. The ability of A. flavus to produce dozens of secondary metabolites, in addition to aflatoxins, has created a new avenue of research for understanding the role these metabolites play in the survival and biodiversity of this fungus. The understanding of A. flavus, the aflatoxin contamination problem, and control measures to prevent the contamination has become a unique example for an integrated approach to safeguard global food and feed safety.
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Affiliation(s)
- D. Bhatnagar
- US Department of Agriculture, Agricultural Research Service, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA
| | - K. Rajasekaran
- US Department of Agriculture, Agricultural Research Service, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA
| | - M. Gilbert
- US Department of Agriculture, Agricultural Research Service, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA
| | - J.W. Cary
- US Department of Agriculture, Agricultural Research Service, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA
| | - N. Magan
- Applied Mycology Group, Cranfield University, MK45 4DT, Cranfield, United Kingdom
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Yao G, Zhang F, Nie X, Wang X, Yuan J, Zhuang Z, Wang S. Essential APSES Transcription Factors for Mycotoxin Synthesis, Fungal Development, and Pathogenicity in Aspergillus flavus. Front Microbiol 2017; 8:2277. [PMID: 29209291 PMCID: PMC5702001 DOI: 10.3389/fmicb.2017.02277] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/06/2017] [Indexed: 02/04/2023] Open
Abstract
Aflatoxins are a potent carcinogenic mycotoxin and has become a research model of fungal secondary metabolism (SM). Via systematically investigating the APSES transcription factors (TFs), two APSES proteins were identified: AfRafA and AfStuA. These play central roles in the synthesis of mycotoxins including aflatoxin and cyclopiazonic acid, and fungal development and are consequently central to the pathogenicity of the aflatoxigenic A. flavus. Loss of AfRafA not only dramatically suppressed aflatoxin cluster expression, subsequently reducing toxin synthesis both in vitro and in vivo, but also impaired conidia and sclerotia development. More importantly, aflatoxin biosynthesis as well as conidia and sclerotia development were fully blocked in ΔAfStuA. In addition, our results supported that AfStuA regulated the aflatoxin synthesis in an AflR-dependent manner. Intriguingly, it was revealed that AfRafA and AfStuA exert an antagonistic role in the regulation of biosynthesis of cyclopiazonic acid. In summary, two global transcriptional regulators for fungal development, mycotoxin production, and seed pathogenicity of the A. flavus system have been established. The two novel regulators of mycotoxins are promising targets for future plant breeding and for the development of fungicides.
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Affiliation(s)
- Guangshan Yao
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Feng Zhang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xinyi Nie
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xiuna Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jun Yuan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zhenhong Zhuang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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Yun CS, Motoyama T, Osada H. Regulatory Mechanism of Mycotoxin Tenuazonic Acid Production in Pyricularia oryzae. ACS Chem Biol 2017; 12:2270-2274. [PMID: 28820236 DOI: 10.1021/acschembio.7b00353] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Tenuazonic acid (TeA) is a mycotoxin produced by the rice blast fungus Pyricularia oryzae and some plant pathogenic fungi. We previously demonstrated that TeA is biosynthesized in P. oryzae by TeA synthetase 1 (TAS1) and that its production is induced by osmo-sensory MAPK-encoding gene (OSM1) deletion or the addition of 1% DMSO to cultures; however, the regulatory mechanisms of TeA production were unknown. Here, we identify a Zn(II)2-Cys6-type transcription factor in the upstream region of TAS1, which is encoded by TAS2 and regulates TeA production. We also find PoLAE1, which is a homologue of LaeA, a regulator of fungal secondary metabolism. Analysis of PoLAE1 deletion and overexpression strains indicate that PoLAE1 drives TeA production. We also demonstrate that two TeA-inducing signals, 1% DMSO addition and OSM1 deletion, were transmitted through PoLAE1. Our results indicate that TeA production is regulated by two specific regulators, TAS2 and PoLAE1, in P. oryzae.
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Affiliation(s)
- Choong-Soo Yun
- Chemical Biology Research
Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Takayuki Motoyama
- Chemical Biology Research
Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Hiroyuki Osada
- Chemical Biology Research
Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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Pfannenstiel BT, Zhao X, Wortman J, Wiemann P, Throckmorton K, Spraker JE, Soukup AA, Luo X, Lindner DL, Lim FY, Knox BP, Haas B, Fischer GJ, Choera T, Butchko RAE, Bok JW, Affeldt KJ, Keller NP, Palmer JM. Revitalization of a Forward Genetic Screen Identifies Three New Regulators of Fungal Secondary Metabolism in the Genus Aspergillus. mBio 2017; 8:e01246-17. [PMID: 28874473 PMCID: PMC5587912 DOI: 10.1128/mbio.01246-17] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/08/2017] [Indexed: 11/24/2022] Open
Abstract
The study of aflatoxin in Aspergillus spp. has garnered the attention of many researchers due to aflatoxin's carcinogenic properties and frequency as a food and feed contaminant. Significant progress has been made by utilizing the model organism Aspergillus nidulans to characterize the regulation of sterigmatocystin (ST), the penultimate precursor of aflatoxin. A previous forward genetic screen identified 23 A. nidulans mutants involved in regulating ST production. Six mutants were characterized from this screen using classical mapping (five mutations in mcsA) and complementation with a cosmid library (one mutation in laeA). The remaining mutants were backcrossed and sequenced using Illumina and Ion Torrent sequencing platforms. All but one mutant contained one or more sequence variants in predicted open reading frames. Deletion of these genes resulted in identification of mutant alleles responsible for the loss of ST production in 12 of the 17 remaining mutants. Eight of these mutations were in genes already known to affect ST synthesis (laeA, mcsA, fluG, and stcA), while the remaining four mutations (in laeB, sntB, and hamI) were in previously uncharacterized genes not known to be involved in ST production. Deletion of laeB, sntB, and hamI in A. flavus results in loss of aflatoxin production, confirming that these regulators are conserved in the aflatoxigenic aspergilli. This report highlights the multifaceted regulatory mechanisms governing secondary metabolism in Aspergillus Additionally, these data contribute to the increasing number of studies showing that forward genetic screens of fungi coupled with whole-genome resequencing is a robust and cost-effective technique.IMPORTANCE In a postgenomic world, reverse genetic approaches have displaced their forward genetic counterparts. The techniques used in forward genetics to identify loci of interest were typically very cumbersome and time-consuming, relying on Mendelian traits in model organisms. The current work was pursued not only to identify alleles involved in regulation of secondary metabolism but also to demonstrate a return to forward genetics to track phenotypes and to discover genetic pathways that could not be predicted through a reverse genetics approach. While identification of mutant alleles from whole-genome sequencing has been done before, here we illustrate the possibility of coupling this strategy with a genetic screen to identify multiple alleles of interest. Sequencing of classically derived mutants revealed several uncharacterized genes, which represent novel pathways to regulate and control the biosynthesis of sterigmatocystin and of aflatoxin, a societally and medically important mycotoxin.
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Affiliation(s)
| | - Xixi Zhao
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Jennifer Wortman
- Genome Sequencing and Analysis Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Philipp Wiemann
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kurt Throckmorton
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Joseph E Spraker
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Alexandra A Soukup
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Xingyu Luo
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Daniel L Lindner
- Center for Forest Mycology Research, Northern Research Station, U.S. Forest Service, Madison, Wisconsin, USA
| | - Fang Yun Lim
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Benjamin P Knox
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Brian Haas
- Genome Sequencing and Analysis Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Gregory J Fischer
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tsokyi Choera
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Robert A E Butchko
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, USA
| | - Jin-Woo Bok
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Katharyn J Affeldt
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jonathan M Palmer
- Center for Forest Mycology Research, Northern Research Station, U.S. Forest Service, Madison, Wisconsin, USA
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33
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Niehaus EM, Studt L, von Bargen KW, Kummer W, Humpf HU, Reuter G, Tudzynski B. Sound of silence: the beauvericin cluster in Fusarium fujikuroi is controlled by cluster-specific and global regulators mediated by H3K27 modification. Environ Microbiol 2017; 18:4282-4302. [PMID: 27750383 DOI: 10.1111/1462-2920.13576] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/11/2016] [Indexed: 01/25/2023]
Abstract
In this study, we compared the secondary metabolite profile of Fusarium fujikuroi and the histone deacetylase mutant ΔHDA1. We identified a novel peak in ΔHDA1, which was identified as beauvericin (BEA). Going in line with a 1000-fold increased BEA production, the respective non-ribosomal peptide synthetase (NRPS)-encoding gene (BEA1), as well as two adjacent genes (BEA2-BEA3), were significantly up-regulated in ΔHDA1 compared to the wild type. A special role was revealed for the ABC transporter Bea3: deletion of the encoding gene resulted in significant up-regulation of BEA1 and BEA2 and drastically elevated product yields. Furthermore, mutation of a conserved sequence motif in the promoter of BEA1 released BEA repression and resulted in elevated product levels. Candidate transcription factors (TFs) that could bind to this motif are the cluster-specific TF Bea4 as well as a homolog of the global mammalian Kruppel-like TF Yin Yang 1 (Yy1), both acting as repressors of BEA biosynthesis. In addition to Hda1, BEA biosynthesis is repressed by the activity of the H3K27 methyltransferase Kmt6. Consistently, Western blot analyses revealed a genome-wide enrichment of H3K27 acetylation (H3K27ac) in the ΔHDA1 and KMT6 knock-down mutants. Subsequent chromatin immunoprecipitation (ChIP) experiments showed elevated H3K27ac modification levels at the BEA cluster.
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Affiliation(s)
- Eva-Maria Niehaus
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Schlossplatz 8, Münster, D-48143
| | - Lena Studt
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Schlossplatz 8, Münster, D-48143
| | - Katharina W von Bargen
- Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 45, Münster, D-48149
| | - Wiebke Kummer
- Institut für Genetik, Martin Luther Universität Halle-Wittenberg, Weinbergweg 10, Halle (Saale), D-06120
| | - Hans-Ulrich Humpf
- Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 45, Münster, D-48149
| | - Gunter Reuter
- Institut für Genetik, Martin Luther Universität Halle-Wittenberg, Weinbergweg 10, Halle (Saale), D-06120
| | - Bettina Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Schlossplatz 8, Münster, D-48143
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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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Itoh E, Odakura R, Oinuma KI, Shimizu M, Masuo S, Takaya N. Sirtuin E is a fungal global transcriptional regulator that determines the transition from the primary growth to the stationary phase. J Biol Chem 2017; 292:11043-11054. [PMID: 28465348 PMCID: PMC5491787 DOI: 10.1074/jbc.m116.753772] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 04/20/2017] [Indexed: 11/06/2022] Open
Abstract
In response to limited nutrients, fungal cells exit the primary growth phase, enter the stationary phase, and cease proliferation. Although fundamental to microbial physiology in many environments, the regulation of this transition is poorly understood but likely involves many transcriptional regulators. These may include the sirtuins, which deacetylate acetyllysine residues of histones and epigenetically regulate global transcription. Therefore, we investigated the role of a nuclear sirtuin, sirtuin E (SirE), from the ascomycete fungus Aspergillus nidulans An A. nidulans strain with a disrupted sirE gene (SirEΔ) accumulated more acetylated histone H3 during the stationary growth phase when sirE was expressed at increased levels in the wild type. SirEΔ exhibited decreased mycelial autolysis, conidiophore development, sterigmatocystin biosynthesis, and production of extracellular hydrolases. Moreover, the transcription of the genes involved in these processes was also decreased, indicating that SirE is a histone deacetylase that up-regulates these activities in the stationary growth phase. Transcriptome analyses indicated that SirE repressed primary carbon and nitrogen metabolism and cell-wall synthesis. Chromatin immunoprecipitation demonstrated that SirE deacetylates acetylated Lys-9 residues in histone H3 at the gene promoters of α-1,3-glucan synthase (agsB), glycolytic phosphofructokinase (pfkA), and glyceraldehyde 3-phosphate (gpdA), indicating that SirE represses the expression of these primary metabolic genes. In summary, these results indicate that SirE facilitates the metabolic transition from the primary growth phase to the stationary phase. Because the observed gene expression profiles in stationary phase matched those resulting from carbon starvation, SirE appears to control this metabolic transition via a mechanism associated with the starvation response.
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Affiliation(s)
- Eriko Itoh
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Rika Odakura
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Ken-Ichi Oinuma
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Motoyuki Shimizu
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Shunsuke Masuo
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Naoki Takaya
- From the Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
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36
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Wilkinson HH, Ramaswamy A, Sim SC, Keller NP. Increased conidiation associated with progression along the sterigmatocystin biosynthetic pathway. Mycologia 2017. [DOI: 10.1080/15572536.2005.11832867] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Anitha Ramaswamy
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77845-2132
| | | | - Nancy P. Keller
- Department of Plant Pathology, University of Wisconsin, 1630 Linden Drive, Madison, Wisconsin 53706
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37
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Baquião AC, Lopes EL, Corrêa B. Molecular and mycotoxigenic biodiversity of Aspergillus flavus isolated from Brazil nuts. Food Res Int 2016; 89:266-271. [PMID: 28460913 DOI: 10.1016/j.foodres.2016.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/14/2016] [Accepted: 08/07/2016] [Indexed: 01/20/2023]
Abstract
The objective of this study was to carry out a transcription analysis of eight genes belonging to the aflatoxin (AF) and cyclopiazonic acid (CPA) biosynthesis pathway, and to detect aflatoxin B1 (AFB1) and CPA production in Aspergillus flavus strains isolated from Brazil nuts. Additionally, these genes were correlated with the different mycotoxigenic profiles of the same strains. Four previously identified A. flavus strains (ICB-01, ICB-151, ICB-161, and ICB-165) were grown on Brazil nut agar at 25°C for 10days. Mycotoxins were separated by high-performance liquid chromatography. Transcriptional analysis was performed by real-time RT-PCR using specific primers designed based on the conserved regions of two regulatory genes (aflR and aflS), three structural genes of the AFB1 biosynthesis pathway (aflH, aflJ and aflP), and three structural genes of the CPA biosynthesis pathway (maoA, dmaT and pks-nrps). The expression of most genes in the A. flavus isolates varied according to the mycotoxin profile of each strain. The most expressed genes in the aflatoxigenic strain ICB-151 were aflJ (77.11%) and aflH (32.75%), while the CPA-producing strain ICB-161 mainly expressed dmaT (100%), maoA (63.72%), aflS (43.52%), and aflR (42.63%). The ICB-01 isolate was a producer of AFB1 and CPA and the most expressed genes were aflS (47.79%), dmaT (42.77%), aflP (39.5%), and aflR (38.02%). ICB-198 did not produce any mycotoxin and exhibited lower expression of almost all genes analyzed. Furthermore, the ratio of aflS/aflR expression was correlated with the biosynthesis of AF and CPA in A. flavus strains producing exclusively AF or CPA or producing both AF and CPA. The ratio of aflS/aflR expression therefore seems to be related to the production of mycotoxins in Brazil nuts. Our results provide important data for the development of innovative and more cost-effective strategies to reduce and prevent AFB and CPA contamination in Brazil nuts.
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Affiliation(s)
- Arianne Costa Baquião
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, CEP 05508-000 São Paulo, Brazil.
| | - Evandro Luiz Lopes
- Escola Paulista de Política, Economia e Negócios, Universidade Federal de São Paulo, Brazil
| | - Benedito Corrêa
- Departamento de Microbiologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, CEP 05508-000 São Paulo, Brazil
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Snini SP, Tannous J, Heuillard P, Bailly S, Lippi Y, Zehraoui E, Barreau C, Oswald IP, Puel O. Patulin is a cultivar-dependent aggressiveness factor favouring the colonization of apples by Penicillium expansum. MOLECULAR PLANT PATHOLOGY 2016; 17:920-30. [PMID: 26582186 PMCID: PMC6638343 DOI: 10.1111/mpp.12338] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The blue mould decay of apples is caused by Penicillium expansum and is associated with contamination by patulin, a worldwide regulated mycotoxin. Recently, a cluster of 15 genes (patA-patO) involved in patulin biosynthesis was identified in P. expansum. blast analysis revealed that patL encodes a Cys6 zinc finger regulatory factor. The deletion of patL caused a drastic decrease in the expression of all pat genes, leading to an absence of patulin production. Pathogenicity studies performed on 13 apple varieties indicated that the PeΔpatL strain could still infect apples, but the intensity of symptoms was weaker compared with the wild-type strain. A lower growth rate was observed in the PeΔpatL strain when this strain was grown on nine of the 13 apple varieties tested. In the complemented PeΔpatL:patL strain, the ability to grow normally in apple and the production of patulin were restored. Our results clearly demonstrate that patulin is not indispensable in the initiation of the disease, but acts as a cultivar-dependent aggressiveness factor for P. expansum. This conclusion was strengthened by the fact that the addition of patulin to apple infected by the PeΔpatL mutant restored the normal fungal colonization in apple.
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Affiliation(s)
- Selma P Snini
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
| | - Joanna Tannous
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
- Université Saint-Joseph, Centre d'Analyses et de Recherches (Faculté des Sciences), Campus des Sciences et Technologies, Mar Roukos, Mkallès, PO Box 11-514 Riad El Solh, Beyrouth, 1107 2050, Lebanon
| | - Pauline Heuillard
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
| | - Sylviane Bailly
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
| | - Yannick Lippi
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
| | - Enric Zehraoui
- INRA, UR1264 - MycSA, CS20032, F-33883, Villenave d'Ornon Cedex, France
| | - Christian Barreau
- INRA, UR1264 - MycSA, CS20032, F-33883, Villenave d'Ornon Cedex, France
| | - Isabelle P Oswald
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
| | - Olivier Puel
- INRA, UMR 1331, Toxalim, Research Centre in Food Toxicology, 180 Chemin de Tournefeuille, F-31027, Toulouse Cedex, France
- Université de Toulouse III, ENVT, INP, UMR 1331, Toxalim, F-31076, Toulouse, France
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Alves PC, Hartmann DO, Núñez O, Martins I, Gomes TL, Garcia H, Galceran MT, Hampson R, Becker JD, Silva Pereira C. Transcriptomic and metabolomic profiling of ionic liquid stimuli unveils enhanced secondary metabolism in Aspergillus nidulans. BMC Genomics 2016; 17:284. [PMID: 27072538 PMCID: PMC4830055 DOI: 10.1186/s12864-016-2577-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/08/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The inherent potential of filamentous fungi, especially of Ascomycota, for producing diverse bioactive metabolites remains largely silent under standard laboratory culture conditions. Innumerable strategies have been described to trigger their production, one of the simplest being manipulation of the growth media composition. Supplementing media with ionic liquids surprisingly enhanced the diversity of extracellular metabolites generated by penicillia. This finding led us to evaluate the impact of ionic liquids' stimuli on the fungal metabolism in Aspergillus nidulans and how it reflects on the biosynthesis of secondary metabolites (SMs). RESULTS Whole transcriptional profiling showed that exposure to 0.7 M cholinium chloride or 1-ethyl-3-methylimidazolium chloride dramatically affected expression of genes encoding both primary and secondary metabolism. Both ionic liquids apparently induced stress responses and detoxification mechanisms but response profiles to each stimulus were unique. Primary metabolism was up-regulated by choline, but down-regulated by 1-ethyl-3-methylimidazolium chloride; both stimulated production of acetyl-CoA (key precursor to numerous SMs) and non proteinogenic amino acids (building blocks of bioactive classes of SMs). In total, twenty one of the sixty six described backbone genes underwent up-regulation. Accordingly, differential analysis of the fungal metabolome showed that supplementing growth media with ionic liquids resulted in ca. 40 differentially accumulated ion masses compared to control conditions. In particular, it stimulated production of monodictyphenone and orsellinic acid, otherwise cryptic. Expression levels of genes encoding corresponding polyketide biosynthetic enzymes (i.e. backbone genes) increased compared to control conditions. The corresponding metabolite extracts showed increased cell polarity modulation potential in an ex vivo whole tissue assay (The lial Live Targeted Epithelia; theLiTE™). CONCLUSIONS Ionic liquids, a diverse class of chemicals composed solely of ions, can provide an unexpected means to further resolve the diversity of natural compounds, guiding discovery of fungal metabolites with clinical potential.
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Affiliation(s)
- Paula C Alves
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Diego O Hartmann
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Oscar Núñez
- Department of Analytical Chemistry, University of Barcelona, Diagonal 645, E-08028, Barcelona, Spain.,Serra Hunter Fellow, Generalitat de Catalunya, Barcelona, Spain
| | - Isabel Martins
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Teresa L Gomes
- Thelial Technologies S.A., Parque Tecnológico de Cantanhede, Nucleo 04 Lote 3, 3060-197, Cantanhede, Portugal
| | - Helga Garcia
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Maria Teresa Galceran
- Department of Analytical Chemistry, University of Barcelona, Diagonal 645, E-08028, Barcelona, Spain
| | - Richard Hampson
- Thelial Technologies S.A., Parque Tecnológico de Cantanhede, Nucleo 04 Lote 3, 3060-197, Cantanhede, Portugal
| | - Jörg D Becker
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156, Oeiras, Portugal
| | - Cristina Silva Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
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Zhuang Z, Lohmar JM, Satterlee T, Cary JW, Calvo AM. The Master Transcription Factor mtfA Governs Aflatoxin Production, Morphological Development and Pathogenicity in the Fungus Aspergillus flavus. Toxins (Basel) 2016; 8:toxins8010029. [PMID: 26805883 PMCID: PMC4728551 DOI: 10.3390/toxins8010029] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 12/23/2015] [Accepted: 01/06/2016] [Indexed: 11/30/2022] Open
Abstract
Aspergillus flavus produces a variety of toxic secondary metabolites; among them, the aflatoxins (AFs) are the most well known. These compounds are highly mutagenic and carcinogenic, particularly AFB1. A. flavus is capable of colonizing a number of economically-important crops, such as corn, cotton, peanut and tree nuts, and contaminating them with AFs. Molecular genetic studies in A. flavus could identify novel gene targets for use in strategies to reduce AF contamination and its adverse impact on food and feed supplies worldwide. In the current study, we investigated the role of the master transcription factor gene mtfA in A. flavus. Our results revealed that forced overexpression of mtfA results in a drastic decrease or elimination of several secondary metabolites, among them AFB1. The reduction in AFB1 was accompanied by a decrease in aflR expression. Furthermore, mtfA also regulates development; conidiation was influenced differently by this gene depending on the type of colonized substrate. In addition to its effect on conidiation, mtfA is necessary for the normal maturation of sclerotia. Importantly, mtfA positively affects the pathogenicity of A. flavus when colonizing peanut seeds. AF production in colonized seeds was decreased in the deletion mtfA strain and particularly in the overexpression strain, where only trace amounts were detected. Interestingly, a more rapid colonization of the seed tissue occurred when mtfA was overexpressed, coinciding with an increase in lipase activity and faster maceration of the oily part of the seed.
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Affiliation(s)
- Zhenhong Zhuang
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Jessica M Lohmar
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Timothy Satterlee
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
| | - Jeffrey W Cary
- Food and Feed Safety Research Unit, USDA/ARS, Southern Regional Research Center, New Orleans, LA 70124, USA.
| | - Ana M Calvo
- Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., Dekalb, IL 60115, USA.
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Deepika VB, Murali TS, Satyamoorthy K. Modulation of genetic clusters for synthesis of bioactive molecules in fungal endophytes: A review. Microbiol Res 2015; 182:125-40. [PMID: 26686621 DOI: 10.1016/j.micres.2015.10.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/21/2015] [Accepted: 10/26/2015] [Indexed: 11/26/2022]
Abstract
Novel drugs with unique and targeted mode of action are very much need of the hour to treat and manage severe multidrug infections and other life-threatening complications. Though natural molecules have proved to be effective and environmentally safe, the relative paucity of discovery of new drugs has forced us to lean towards synthetic chemistry for developing novel drug molecules. Plants and microbes are the major resources that we rely upon in our pursuit towards discovery of novel compounds of pharmacological importance with less toxicity. Endophytes, an eclectic group of microbes having the potential to chemically bridge the gap between plants and microbes, have attracted the most attention due to their relatively high metabolic versatility. Since continuous large scale supply of major metabolites from microfungi and especially endophytes is severely impeded by the phenomenon of attenuation in axenic cultures, the major challenge is to understand the regulatory mechanisms in operation that drive the expression of metabolic gene clusters of pharmaceutical importance. This review is focused on the major regulatory elements that operate in filamentous fungi and various combinatorial multi-disciplinary approaches involving bioinformatics, molecular biology, and metabolomics that could aid in large scale synthesis of important lead molecules.
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Affiliation(s)
- V B Deepika
- Division of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India
| | - T S Murali
- Division of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India.
| | - K Satyamoorthy
- Division of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India
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43
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Zafra G, Absalón AE, Cortés-Espinosa DV. Morphological changes and growth of filamentous fungi in the presence of high concentrations of PAHs. Braz J Microbiol 2015; 46:937-41. [PMID: 26413081 PMCID: PMC4568862 DOI: 10.1590/s1517-838246320140575] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 12/28/2014] [Indexed: 11/21/2022] Open
Abstract
In this study, we evaluated the effect of low and high molecular weight polycyclic
aromatic hydrocarbons (PAHs), i.e., Phenanthrene, Pyrene and
Benzo[a]pyrene, on the radial growth and morphology of the PAH-degrading fungal
strains Aspergillus nomius H7 and Trichoderma
asperellum H15. The presence of PAHs in solid medium produced significant
detrimental effects on the radial growth of A. nomius H7 at 4,000
and 6,000 mg L−1 and changes in mycelium pigmentation, abundance and
sporulation ability at 1,000–6,000 mg L−1. In contrast, the radial growth
of T. asperellum H15 was not affected at any of the doses tested,
although sporulation was observed only up to 4,000 mg L−1 and as with the
H7 strain, some visible changes in sporulation patterns and mycelium pigmentation
were observed. Our results suggest that fungal strains exposed to high doses of PAHs
significantly vary in their growth rates and sporulation characteristics in response
to the physiological and defense mechanisms that affect both pigment production and
conidiation processes. This finding is relevant for obtaining a better understanding
of fungal adaptation in PAH-polluted environments and for developing and implementing
adequate strategies for the remediation of contaminated soils.
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Affiliation(s)
- German Zafra
- Instituto Politécnico Nacional, Centro de Investigación en Biotecnología Aplicada, Tlaxcala, México
| | - Angel E Absalón
- Instituto Politécnico Nacional, Centro de Investigación en Biotecnología Aplicada, Tlaxcala, México
| | - Diana V Cortés-Espinosa
- Instituto Politécnico Nacional, Centro de Investigación en Biotecnología Aplicada, Tlaxcala, México
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Li B, Zong Y, Du Z, Chen Y, Zhang Z, Qin G, Zhao W, Tian S. Genomic Characterization Reveals Insights Into Patulin Biosynthesis and Pathogenicity in Penicillium Species. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:635-47. [PMID: 25625822 DOI: 10.1094/mpmi-12-14-0398-fi] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Penicillium species are fungal pathogens that infect crop plants worldwide. P. expansum differs from P. italicum and P. digitatum, all major postharvest pathogens of pome and citrus, in that the former is able to produce the mycotoxin patulin and has a broader host range. The molecular basis of host-specificity of fungal pathogens has now become the focus of recent research. The present report provides the whole genome sequence of P. expansum (33.52 Mb) and P. italicum (28.99 Mb) and identifies differences in genome structure, important pathogenic characters, and secondary metabolite (SM) gene clusters in Penicillium species. We identified a total of 55 gene clusters potentially related to secondary metabolism, including a cluster of 15 genes (named PePatA to PePatO), that may be involved in patulin biosynthesis in P. expansum. Functional studies confirmed that PePatL and PePatK play crucial roles in the biosynthesis of patulin and that patulin production is not related to virulence of P. expansum. Collectively, P. expansum contains more pathogenic genes and SM gene clusters, in particular, an intact patulin cluster, than P. italicum or P. digitatum. These findings provide important information relevant to understanding the molecular network of patulin biosynthesis and mechanisms of host-specificity in Penicillium species.
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Affiliation(s)
- Boqiang Li
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yuanyuan Zong
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Zhenglin Du
- 2 Core Genomic Facility, Beijing Institute of Genomics, Chinese Academy of Sciences
| | - Yong Chen
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Zhanquan Zhang
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Guozheng Qin
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Wenming Zhao
- 2 Core Genomic Facility, Beijing Institute of Genomics, Chinese Academy of Sciences
| | - Shiping Tian
- 1 Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China
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Gressler M, Hortschansky P, Geib E, Brock M. A new high-performance heterologous fungal expression system based on regulatory elements from the Aspergillus terreus terrein gene cluster. Front Microbiol 2015; 6:184. [PMID: 25852654 PMCID: PMC4360782 DOI: 10.3389/fmicb.2015.00184] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/19/2015] [Indexed: 11/13/2022] Open
Abstract
Recently, the Aspergillus terreus terrein gene cluster was identified and selected for development of a new heterologous expression system. The cluster encodes the specific transcription factor TerR that is indispensable for terrein cluster induction. To identify TerR binding sites, different recombinant versions of the TerR DNA-binding domain were analyzed for specific motif recognition. The high affinity consensus motif TCGGHHWYHCGGH was identified from genes required for terrein production and binding site mutations confirmed their essential contribution to gene expression in A. terreus. A combination of TerR with its terA target promoter was tested as recombinant expression system in the heterologous host Aspergillus niger. TerR mediated target promoter activation was directly dependent on its transcription level. Therefore, terR was expressed under control of the regulatable amylase promoter PamyB and the resulting activation of the terA target promoter was compared with activation levels obtained from direct expression of reporters from the strong gpdA control promoter. Here, the coupled system outcompeted the direct expression system. When the coupled system was used for heterologous polyketide synthase expression high metabolite levels were produced. Additionally, expression of the Aspergillus nidulans polyketide synthase gene orsA revealed lecanoric acid rather than orsellinic acid as major polyketide synthase product. Domain swapping experiments assigned this depside formation from orsellinic acid to the OrsA thioesterase domain. These experiments confirm the suitability of the expression system especially for high-level metabolite production in heterologous hosts.
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Affiliation(s)
- Markus Gressler
- Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute Jena, Germany
| | - Peter Hortschansky
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute Jena, Germany
| | - Elena Geib
- Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute Jena, Germany
| | - Matthias Brock
- Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute Jena, Germany ; Institute for Microbiology, Friedrich Schiller University Jena, Germany
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46
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Sheridan KJ, Dolan SK, Doyle S. Endogenous cross-talk of fungal metabolites. Front Microbiol 2015; 5:732. [PMID: 25601857 PMCID: PMC4283610 DOI: 10.3389/fmicb.2014.00732] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/04/2014] [Indexed: 12/21/2022] Open
Abstract
Non-ribosomal peptide (NRP) synthesis in fungi requires a ready supply of proteogenic and non-proteogenic amino acids which are subsequently incorporated into the nascent NRP via a thiotemplate mechanism catalyzed by NRP synthetases. Substrate amino acids can be modified prior to or during incorporation into the NRP, or following incorporation into an early stage amino acid-containing biosynthetic intermediate. These post-incorporation modifications involve a range of additional enzymatic activities including but not exclusively, monooxygenases, methyltransferases, epimerases, oxidoreductases, and glutathione S-transferases which are essential to effect biosynthesis of the final NRP. Likewise, polyketide biosynthesis is directly by polyketide synthase megaenzymes and cluster-encoded ancillary decorating enzymes. Additionally, a suite of additional primary metabolites, for example: coenzyme A (CoA), acetyl CoA, S-adenosylmethionine, glutathione (GSH), NADPH, malonyl CoA, and molecular oxygen, amongst others are required for NRP and polyketide synthesis (PKS). Clearly these processes must involve exquisite orchestration to facilitate the simultaneous biosynthesis of different types of NRPs, polyketides, and related metabolites requiring identical or similar biosynthetic precursors or co-factors. Moreover, the near identical structures of many natural products within a given family (e.g., ergot alkaloids), along with localization to similar regions within fungi (e.g., conidia) suggests that cross-talk may exist, in terms of biosynthesis and functionality. Finally, we speculate if certain biosynthetic steps involved in NRP and PKS play a role in cellular protection or environmental adaptation, and wonder if these enzymatic reactions are of equivalent importance to the actual biosynthesis of the final metabolite.
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Affiliation(s)
| | - Stephen K Dolan
- Department of Biology, Maynooth University Maynooth, Ireland
| | - Sean Doyle
- Department of Biology, Maynooth University Maynooth, Ireland
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Abstract
Mycotoxins are natural contaminants of food and feed products, posing a substantial health risk to humans and animals throughout the world. A plethora of filamentous fungi has been identified as mycotoxin producers and most of these fungal species belong to the genera Aspergillus, Fusarium, and Penicillium. A number of studies have been conducted to better understand the molecular mechanisms of biosynthesis of key mycotoxins and the regulatory cascades controlling toxigenesis. In many cases, the mycotoxin biosynthetic genes are clustered and regulated by one or more pathway-specific transcription factor(s). In addition, as biosynthesis of many secondary metabolites is coordinated with fungal growth and development, there are a number of upstream regulators affecting biosynthesis of mycotoxins in fungi. This review presents a concise summary of the regulation of mycotoxin biosynthesis, focusing on the roles of the upstream regulatory elements governing biosynthesis of aflatoxin and sterigmatocystin in Aspergillus.
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Affiliation(s)
| | - Jae-Hyuk Yu
- University of Wisconsin-Madison, Madison, Wisconsin, USA
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49
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Ishidoh KI, Kinoshita H, Nihira T. Identification of a gene cluster responsible for the biosynthesis of cyclic lipopeptide verlamelin. Appl Microbiol Biotechnol 2014; 98:7501-10. [PMID: 24848421 DOI: 10.1007/s00253-014-5803-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 03/29/2014] [Accepted: 04/29/2014] [Indexed: 12/22/2022]
Abstract
Only limited studies are available on the molecular-level biosynthesis of cyclic lipopeptides (cyclic and hybrid molecules consisting of peptide and fatty acid moieties) in filamentous fungi. Here, we identified and characterized biosynthetic genes of the cyclic lipopeptides, known as verlamelins. Only four genes, coding for non-ribosomal peptide synthetase (NRPS), fatty acid hydroxylase, thioesterase, and AMP-dependent ligase, were found to be involved in verlamelin biosynthesis by the analysis of corresponding gene knockouts. Surprisingly, no gene(s) coding for fatty acid synthase or polyketide synthase was present in the cluster, while verlamelin A/B contained a 5-hydroxytetradecanoic acid moiety. Precursor feeding experiment indicated that both fatty acid hydroxylase and thioesterase are involved to supply 5-hydroxytetradecanoic acid. The results suggested that 5-hydroxytetradecanoic acid was supplied from primary metabolism via fatty acid hydroxylase and loaded onto NRPS. Elongation of the peptide and final cyclization were accomplished by NRPS. The knowledge obtained through this study should provide new insight into fungal lipopeptide biosynthesis.
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Affiliation(s)
- Kei-Ichi Ishidoh
- International Center for Biotechnology, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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50
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Molecular mechanisms of Aspergillus flavus secondary metabolism and development. Fungal Genet Biol 2014; 66:11-8. [DOI: 10.1016/j.fgb.2014.02.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 12/16/2022]
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