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Kumar P, Gupta A, Mahato DK, Pandhi S, Pandey AK, Kargwal R, Mishra S, Suhag R, Sharma N, Saurabh V, Paul V, Kumar M, Selvakumar R, Gamlath S, Kamle M, Enshasy HAE, Mokhtar JA, Harakeh S. Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies. Toxins (Basel) 2022; 14:toxins14100687. [PMID: 36287956 PMCID: PMC9609140 DOI: 10.3390/toxins14100687] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
Cereals and cereal-based products are primary sources of nutrition across the world. However, contamination of these foods with aflatoxins (AFs), secondary metabolites produced by several fungal species, has raised serious concerns. AF generation in innate substrates is influenced by several parameters, including the substrate type, fungus species, moisture content, minerals, humidity, temperature, and physical injury to the kernels. Consumption of AF-contaminated cereals and cereal-based products can lead to both acute and chronic health issues related to physical and mental maturity, reproduction, and the nervous system. Therefore, the precise detection methods, detoxification, and management strategies of AFs in cereal and cereal-based products are crucial for food safety as well as consumer health. Hence, this review provides a brief overview of the occurrence, chemical characteristics, biosynthetic processes, health hazards, and detection techniques of AFs, along with a focus on detoxification and management strategies that could be implemented for food safety and security.
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Affiliation(s)
- Pradeep Kumar
- Department of Botany, University of Lucknow, Lucknow 226007, India
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
- Correspondence: (P.K.); (D.K.M.)
| | - Akansha Gupta
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Dipendra Kumar Mahato
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
- Correspondence: (P.K.); (D.K.M.)
| | - Shikha Pandhi
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Arun Kumar Pandey
- MMICT&BM(HM), Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala 133207, India
| | - Raveena Kargwal
- Department of Processing and Food Engineering, College of Agricultural Engineering and Technology, Chaudhary Charan Singh Haryana Agricultural University, Hisar 125004, India
| | - Sadhna Mishra
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- Faculty of Agricultural Sciences, GLA University, Mathura 281406, India
| | - Rajat Suhag
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
| | - Nitya Sharma
- Food and Bioprocess Engineering Laboratory, Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vivek Saurabh
- Division of Food Science and Postharvest Technology, ICAR—Indian Agricultural Research Institute, New Delhi 110012, India
| | - Veena Paul
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Manoj Kumar
- Chemical and Biochemical Processing Division, ICAR—Central Institute for Research on Cotton Technology, Mumbai 400019, India
| | - Raman Selvakumar
- Centre for Protected Cultivation Technology, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi 110012, India
| | - Shirani Gamlath
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Madhu Kamle
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
| | - Hesham Ali El Enshasy
- Institute of Bioproduct Development, Universiti Teknologi Malaysia (UTM), Skudai 81310, Malaysia
- City of Scientific Research and Technology Applications, New Burg Al Arab, Alexandria 21934, Egypt
| | - Jawahir A. Mokhtar
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia
- Vaccines and Immunotherapy Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Steve Harakeh
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Yousef Abdul Latif Jameel Scientific Chair of Prophetic Medicine Application, Faculty of Medicine (FM), King Abdulaziz University, Jeddah 21589, Saudi Arabia
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Skellam E. Subcellular localization of fungal specialized metabolites. Fungal Biol Biotechnol 2022; 9:11. [PMID: 35614515 PMCID: PMC9134587 DOI: 10.1186/s40694-022-00140-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 05/10/2022] [Indexed: 01/07/2023] Open
Abstract
Fungal specialized metabolites play an important role in the environment and have impacted human health and survival significantly. These specialized metabolites are often the end product of a series of sequential and collaborating biosynthetic enzymes that reside within different subcellular compartments. A wide variety of methods have been developed to understand fungal specialized metabolite biosynthesis in terms of the chemical conversions and the biosynthetic enzymes required, however there are far fewer studies elucidating the compartmentalization of the same enzymes. This review illustrates the biosynthesis of specialized metabolites where the localization of all, or some, of the biosynthetic enzymes have been determined and describes the methods used to identify the sub-cellular localization.
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Affiliation(s)
- Elizabeth Skellam
- Department of Chemistry and BioDiscovery Institute, University of North Texas, 1155 Union Circle, Denton, TX, 76201, USA.
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Hill R, Buggs RJA, Vu DT, Gaya E. Lifestyle Transitions in Fusarioid Fungi are Frequent and Lack Clear Genomic Signatures. Mol Biol Evol 2022; 39:6575681. [PMID: 35484861 PMCID: PMC9051438 DOI: 10.1093/molbev/msac085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The fungal genus Fusarium (Ascomycota) includes well-known plant pathogens that are implicated in diseases worldwide, and many of which have been genome sequenced. The genus also encompasses other diverse lifestyles, including species found ubiquitously as asymptomatic-plant inhabitants (endophytes). Here, we produced structurally annotated genome assemblies for five endophytic Fusarium strains, including the first whole-genome data for Fusarium chuoi. Phylogenomic reconstruction of Fusarium and closely related genera revealed multiple and frequent lifestyle transitions, the major exception being a monophyletic clade of mutualist insect symbionts. Differential codon usage bias and increased codon optimisation separated Fusarium sensu stricto from allied genera. We performed computational prediction of candidate secreted effector proteins (CSEPs) and carbohydrate-active enzymes (CAZymes)—both likely to be involved in the host–fungal interaction—and sought evidence that their frequencies could predict lifestyle. However, phylogenetic distance described gene variance better than lifestyle did. There was no significant difference in CSEP, CAZyme, or gene repertoires between phytopathogenic and endophytic strains, although we did find some evidence that gene copy number variation may be contributing to pathogenicity. Large numbers of accessory CSEPs (i.e., present in more than one taxon but not all) and a comparatively low number of strain-specific CSEPs suggested there is a limited specialisation among plant associated Fusarium species. We also found half of the core genes to be under positive selection and identified specific CSEPs and CAZymes predicted to be positively selected on certain lineages. Our results depict fusarioid fungi as prolific generalists and highlight the difficulty in predicting pathogenic potential in the group.
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Affiliation(s)
- Rowena Hill
- Comparative Fungal Biology, Royal Botanic Gardens Kew, Jodrell Laboratory, Richmond, United Kingdom.,School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Richard J A Buggs
- Comparative Fungal Biology, Royal Botanic Gardens Kew, Jodrell Laboratory, Richmond, United Kingdom.,School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Dang Toan Vu
- Research Planning and International Cooperation Department, Plant Resources Center, Hanoi, Vietnam
| | - Ester Gaya
- Comparative Fungal Biology, Royal Botanic Gardens Kew, Jodrell Laboratory, Richmond, United Kingdom
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Nazhand A, Durazzo A, Lucarini M, Souto EB, Santini A. Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds. Foods 2020; 9:E644. [PMID: 32443392 PMCID: PMC7278662 DOI: 10.3390/foods9050644] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 12/14/2022] Open
Abstract
Mycotoxin contamination continues to be a food safety concern globally, with the most toxic being aflatoxins. On-farm aflatoxins, during food transit or storage, directly or indirectly result in the contamination of foods, which affects the liver, immune system and reproduction after infiltration into human beings and animals. There are numerous reports on aflatoxins focusing on achieving appropriate methods for quantification, precise detection and control in order to ensure consumer safety. In 2012, the International Agency for Research on Cancer (IARC) classified aflatoxins B1, B2, G1, G2, M1 and M2 as group 1 carcinogenic substances, which are a global human health concern. Consequently, this review article addresses aflatoxin chemical properties and biosynthetic processes; aflatoxin contamination in foods and feeds; health effects in human beings and animals due to aflatoxin exposure, as well as aflatoxin detection and detoxification methods.
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Affiliation(s)
- Amirhossein Nazhand
- Department of Biotechnology, Sari Agricultural Science and Natural Resource University, 9th km of Farah Abad Road, Mazandaran 48181-68984, Iran;
| | - Alessandra Durazzo
- CREA-Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Roma, Italy; (A.D.); (M.L.)
| | - Massimo Lucarini
- CREA-Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Roma, Italy; (A.D.); (M.L.)
| | - Eliana B. Souto
- Faculty of Pharmacy of University of Coimbra, Azinhaga de Santa Comba, Polo III-Saúde, 3000-548 Coimbra, Portugal;
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Antonello Santini
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
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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: 134] [Impact Index Per Article: 33.5] [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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Araki Y, Awakawa T, Matsuzaki M, Cho R, Matsuda Y, Hoshino S, Shinohara Y, Yamamoto M, Kido Y, Inaoka DK, Nagamune K, Ito K, Abe I, Kita K. Complete biosynthetic pathways of ascofuranone and ascochlorin in Acremonium egyptiacum. Proc Natl Acad Sci U S A 2019; 116:8269-8274. [PMID: 30952781 PMCID: PMC6486709 DOI: 10.1073/pnas.1819254116] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Ascofuranone (AF) and ascochlorin (AC) are meroterpenoids produced by various filamentous fungi, including Acremonium egyptiacum (synonym: Acremonium sclerotigenum), and exhibit diverse physiological activities. In particular, AF is a promising drug candidate against African trypanosomiasis and a potential anticancer lead compound. These compounds are supposedly biosynthesized through farnesylation of orsellinic acid, but the details have not been established. In this study, we present all of the reactions and responsible genes for AF and AC biosyntheses in A. egyptiacum, identified by heterologous expression, in vitro reconstruction, and gene deletion experiments with the aid of a genome-wide differential expression analysis. Both pathways share the common precursor, ilicicolin A epoxide, which is processed by the membrane-bound terpene cyclase (TPC) AscF in AC biosynthesis. AF biosynthesis branches from the precursor by hydroxylation at C-16 by the P450 monooxygenase AscH, followed by cyclization by a membrane-bound TPC AscI. All genes required for AC biosynthesis (ascABCDEFG) and a transcriptional factor (ascR) form a functional gene cluster, whereas those involved in the late steps of AF biosynthesis (ascHIJ) are present in another distantly located cluster. AF is therefore a rare example of fungal secondary metabolites requiring multilocus biosynthetic clusters, which are likely to be controlled by the single regulator, AscR. Finally, we achieved the selective production of AF in A. egyptiacum by genetically blocking the AC biosynthetic pathway; further manipulation of the strain will lead to the cost-effective mass production required for the clinical use of AF.
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Affiliation(s)
- Yasuko Araki
- Research and Development Division, Kikkoman Corporation, Noda City, Chiba 278-0037, Japan
| | - Takayoshi Awakawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
| | - Motomichi Matsuzaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan;
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki City, Nagasaki 852-8523, Japan
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
| | - Rihe Cho
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yudai Matsuda
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shotaro Hoshino
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yasutomo Shinohara
- Research and Development Division, Kikkoman Corporation, Noda City, Chiba 278-0037, Japan
| | - Masaichi Yamamoto
- Institute of Mitochondrial Science Company, Ltd., Tokyo 176-0025, Japan
| | - Yasutoshi Kido
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Institute of Mitochondrial Science Company, Ltd., Tokyo 176-0025, Japan
- Department of Parasitology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan
| | - Daniel Ken Inaoka
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki City, Nagasaki 852-8523, Japan
- Department of Host-Defense Biochemistry, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan
| | - Kisaburo Nagamune
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - Kotaro Ito
- Research and Development Division, Kikkoman Corporation, Noda City, Chiba 278-0037, Japan
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan;
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kiyoshi Kita
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki City, Nagasaki 852-8523, Japan
- Department of Host-Defense Biochemistry, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan
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Hemmerling F, Hahn F. Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides. Beilstein J Org Chem 2016; 12:1512-50. [PMID: 27559404 PMCID: PMC4979870 DOI: 10.3762/bjoc.12.148] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/22/2016] [Indexed: 01/01/2023] Open
Abstract
This review highlights the biosynthesis of heterocycles in polyketide natural products with a focus on oxygen and nitrogen-containing heterocycles with ring sizes between 3 and 6 atoms. Heterocycles are abundant structural elements of natural products from all classes and they often contribute significantly to their biological activity. Progress in recent years has led to a much better understanding of their biosynthesis. In this context, plenty of novel enzymology has been discovered, suggesting that these pathways are an attractive target for future studies.
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Affiliation(s)
- Franziska Hemmerling
- Institut für Organische Chemie and Zentrum für Biomolekulare Wirkstoffe, Gottfried Wilhelm Leibniz Universität Hannover, Schneiderberg 38, 30167 Hannover, Germany; Fakultät für Biologie, Chemie und Geowissenschaften, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Frank Hahn
- Institut für Organische Chemie and Zentrum für Biomolekulare Wirkstoffe, Gottfried Wilhelm Leibniz Universität Hannover, Schneiderberg 38, 30167 Hannover, Germany; Fakultät für Biologie, Chemie und Geowissenschaften, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
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Tatsuda D, Momose I, Someno T, Sawa R, Kubota Y, Iijima M, Kunisada T, Watanabe T, Shibasaki M, Nomoto A. Quinofuracins A-E, produced by the fungus Staphylotrichum boninense PF1444, show p53-dependent growth suppression. JOURNAL OF NATURAL PRODUCTS 2015; 78:188-195. [PMID: 25611347 DOI: 10.1021/np500581m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Quinofuracins A-E, novel anthraquinone derivatives containing β-D-galactofuranose that were isolated from the fungus Staphylotrichum boninense PF1444, induced p53-dependent cell death in human tumor cells. The structures of quinofuracins A-E, including absolute configurations, were elucidated by extensive spectroscopic analysis and chemical transformation studies. Quinofuracins were classified into three groups according to the aglycone moieties. 5'-Oxoaverantin was present in quinofuracins A-C, whereas averantin and versicolorin B were identified in quinofuracins D and E, respectively. These quinofuracins induced p53-dependent growth suppression in human glioblastoma LNZTA3 cells.
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Affiliation(s)
- Daisuke Tatsuda
- Institute of Microbial Chemistry (BIKAKEN), Numazu , 18-24 Miyamoto, Numazu-shi, Shizuoka 410-0301, Japan
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9
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Yu J. Current understanding on aflatoxin biosynthesis and future perspective in reducing aflatoxin contamination. Toxins (Basel) 2012; 4:1024-57. [PMID: 23202305 PMCID: PMC3509697 DOI: 10.3390/toxins4111024] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 01/20/2023] Open
Abstract
Traditional molecular techniques have been used in research in discovering the genes and enzymes that are involved in aflatoxin formation and genetic regulation. We cloned most, if not all, of the aflatoxin pathway genes. A consensus gene cluster for aflatoxin biosynthesis was discovered in 2005. The factors that affect aflatoxin formation have been studied. In this report, the author summarized the current status of research progress and future possibilities that may be used for solving aflatoxin contamination.
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Affiliation(s)
- Jiujiang Yu
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA/ARS), New Orleans, LA 70112, USA.
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10
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Klejnstrup ML, Frandsen RJN, Holm DK, Nielsen MT, Mortensen UH, Larsen TO, Nielsen JB. Genetics of Polyketide Metabolism in Aspergillus nidulans. Metabolites 2012; 2:100-33. [PMID: 24957370 PMCID: PMC3901194 DOI: 10.3390/metabo2010100] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/23/2011] [Accepted: 01/17/2012] [Indexed: 12/12/2022] Open
Abstract
Secondary metabolites are small molecules that show large structural diversity and a broad range of bioactivities. Some metabolites are attractive as drugs or pigments while others act as harmful mycotoxins. Filamentous fungi have the capacity to produce a wide array of secondary metabolites including polyketides. The majority of genes required for production of these metabolites are mostly organized in gene clusters, which often are silent or barely expressed under laboratory conditions, making discovery and analysis difficult. Fortunately, the genome sequences of several filamentous fungi are publicly available, greatly facilitating the establishment of links between genes and metabolites. This review covers the attempts being made to trigger the activation of polyketide metabolism in the fungal model organism Aspergillus nidulans. Moreover, it will provide an overview of the pathways where ten polyketide synthase genes have been coupled to polyketide products. Therefore, the proposed biosynthesis of the following metabolites will be presented; naphthopyrone, sterigmatocystin, aspyridones, emericellamides, asperthecin, asperfuranone, monodictyphenone/emodin, orsellinic acid, and the austinols.
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Affiliation(s)
- Marie L Klejnstrup
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Rasmus J N Frandsen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B223, DK-2800 Kgs. Lyngby, Denmark.
| | - Dorte K Holm
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B223, DK-2800 Kgs. Lyngby, Denmark.
| | - Morten T Nielsen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B223, DK-2800 Kgs. Lyngby, Denmark.
| | - Uffe H Mortensen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B223, DK-2800 Kgs. Lyngby, Denmark.
| | - Thomas O Larsen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Jakob B Nielsen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B223, DK-2800 Kgs. Lyngby, Denmark.
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11
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YABE K, NAKAJIMA H. Aflatoxin Biosynthesis. Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) 2011; 52:135-47. [DOI: 10.3358/shokueishi.52.135] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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12
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Functional expression and subcellular localization of the aflatoxin pathway enzyme Ver-1 fused to enhanced green fluorescent protein. Appl Environ Microbiol 2008; 74:6385-96. [PMID: 18757582 DOI: 10.1128/aem.01185-08] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aflatoxin, a mycotoxin synthesized by Aspergillus spp., is among the most potent naturally occurring carcinogens known. Little is known about the subcellular organization of aflatoxin synthesis. Previously, we used transmission electron microscopy and immunogold labeling to demonstrate that the late aflatoxin enzyme OmtA localizes primarily to vacuoles in fungal cells on the substrate surface of colonies. In the present work, we monitored subcellular localization of Ver-1 in real time in living cells. Aspergillus parasiticus strain CS10-N2 was transformed with plasmid constructs that express enhanced green fluorescent protein (EGFP) fused to Ver-1. Analysis of transformants demonstrated that EGFP fused to Ver-1 at either the N or C terminus functionally complemented nonfunctional Ver-1 in recipient cells. Western blot analysis detected predominantly full-length Ver-1 fusion proteins in transformants. Confocal laser scanning microscopy demonstrated that Ver-1 fusion proteins localized in the cytoplasm and in the lumen of up to 80% of the vacuoles in hyphae grown for 48 h on solid media. Control EGFP (no Ver-1) expressed in transformants was observed in only 13% of the vacuoles at this time. These data support a model in which middle and late aflatoxin enzymes are synthesized in the cytoplasm and transported to vacuoles, where they participate in aflatoxin synthesis.
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Price MS, Conners SB, Tachdjian S, Kelly RM, Payne GA. Aflatoxin conducive and non-conducive growth conditions reveal new gene associations with aflatoxin production. Fungal Genet Biol 2005; 42:506-18. [PMID: 15878831 DOI: 10.1016/j.fgb.2005.03.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Revised: 03/07/2005] [Accepted: 03/08/2005] [Indexed: 10/25/2022]
Abstract
Research on aflatoxin (AF) production has traditionally focused on defining the AF biosynthetic pathway with the goal of identifying potential targets for intervention. To understand the effect of nitrogen source, carbon source, temperature, and pH on the regulation of AF biosynthesis, a targeted cDNA microarray consisting of genes associated with AF production over time was employed. Expression profiles for genes involved in AF biosynthesis grouped into five clades. A putative regulon was identified consisting of 20 genes that were induced in the conducive nitrogen and pH treatments and the non-conducive carbon and temperature treatments, as well as four other putative regulons corresponding to each of the four variables studied. Seventeen genes exhibited consistent induction/repression profiles across all the experiments. One of these genes was consistently downregulated with AF production. Overexpression of this gene resulted in repression of AF biosynthesis. The cellular function of this gene is currently unresolved.
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Affiliation(s)
- Michael S Price
- Center for Integrated Fungal Research, North Carolina State University, Raleigh, NC 27695-7244, USA
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Sakuno E, Wen Y, Hatabayashi H, Arai H, Aoki C, Yabe K, Nakajima H. Aspergillus parasiticus cyclase catalyzes two dehydration steps in aflatoxin biosynthesis. Appl Environ Microbiol 2005; 71:2999-3006. [PMID: 15932995 PMCID: PMC1151850 DOI: 10.1128/aem.71.6.2999-3006.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the aflatoxin biosynthetic pathway, 5'-oxoaverantin (OAVN) cyclase, the cytosolic enzyme, catalyzes the reaction from OAVN to (2'S,5'S)-averufin (AVR) (E. Sakuno, K. Yabe, and H. Nakajima, Appl. Environ. Microbiol. 69:6418-6426, 2003). Interestingly, the N-terminal 25-amino-acid sequence of OAVN cyclase completely matched an internal sequence of the versiconal (VHOH) cyclase that was deduced from its gene (vbs). The purified OAVN cyclase also catalyzed the reaction from VHOH to versicolorin B (VB). In a competition experiment using the cytosol fraction of Aspergillus parasiticus, a high concentration of VHOH inhibited the enzyme reaction from OAVN to AVR, and instead VB was newly formed. The recombinant Vbs protein, which was expressed in Pichia pastoris, showed OAVN cyclase activity, as well as VHOH cyclase activity. A mutant of A. parasiticus SYS-4 (= NRRL 2999) with vbs deleted accumulated large amounts of OAVN, 5'-hydroxyaverantin, averantin, AVR, and averufanin in the mycelium. These results indicated that the cyclase encoded by the vbs gene is also involved in the reaction from OAVN to AVR in aflatoxin biosynthesis. Small amounts of VHOH, VB, and aflatoxins also accumulated in the same mutant, and this accumulation may have been due to an unknown enzyme(s) not involved in aflatoxin biosynthesis. This is the first report of one enzyme catalyzing two different reactions in a pathway of secondary metabolism.
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Affiliation(s)
- Emi Sakuno
- National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan
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Wen Y, Hatabayashi H, Arai H, Kitamoto HK, Yabe K. Function of the cypX and moxY genes in aflatoxin biosynthesis in Aspergillus parasiticus. Appl Environ Microbiol 2005; 71:3192-8. [PMID: 15933021 PMCID: PMC1151844 DOI: 10.1128/aem.71.6.3192-3198.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pathway oxoaverantin (OAVN) --> averufin (AVR) --> hydroxyversicolorone (HVN) --> versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxigenic Aspergillus parasiticus NRRL 2999. The cypX-deleted mutant lost aflatoxin productivity and accumulated AVR in the mycelia. Although this mutant converted HVN, versicolorone (VONE), VHA, and versiconol acetate (VOAc) to aflatoxins in feeding experiments, it could not produce aflatoxins from either OAVN or AVR. The moxY-deleted mutant also lost aflatoxin productivity, whereas it newly accumulated HVN and VONE. In feeding experiments, this mutant converted either VHA or VOAc to aflatoxins but did not convert OAVN, AVR, HVN, or VONE to aflatoxins. These results demonstrated that cypX encodes AVR monooxygenase, catalyzing the reaction from AVR to HVN, and moxY encodes HVN monooxygenase, catalyzing a Baeyer-Villiger reaction from HVN to VHA as well as from VONE to VOAc. In this work, we devised a simple and rapid method to extract DNA from many fungi for PCR analyses in which cell disruption with a shaker and phenol extraction were combined.
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Affiliation(s)
- Ying Wen
- National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan
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Yu J, Chang PK, Ehrlich KC, Cary JW, Bhatnagar D, Cleveland TE, Payne GA, Linz JE, Woloshuk CP, Bennett JW. Clustered pathway genes in aflatoxin biosynthesis. Appl Environ Microbiol 2004; 70:1253-62. [PMID: 15006741 PMCID: PMC368384 DOI: 10.1128/aem.70.3.1253-1262.2004] [Citation(s) in RCA: 551] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Jiujiang Yu
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, Louisiana 70124, USA.
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