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MacCready JS, Roggenkamp EM, Gdanetz K, Chilvers MI. Elucidating the Obligate Nature and Biological Capacity of an Invasive Fungal Corn Pathogen. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:411-424. [PMID: 36853195 DOI: 10.1094/mpmi-10-22-0213-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Tar spot is a devasting corn disease caused by the obligate fungal pathogen Phyllachora maydis. Since its initial identification in the United States in 2015, P. maydis has become an increasing threat to corn production. Despite this, P. maydis has remained largely understudied at the molecular level, due to difficulties surrounding its obligate lifestyle. Here, we generated a significantly improved P. maydis nuclear and mitochondrial genome, using a combination of long- and short-read technologies, and also provide the first transcriptomic analysis of primary tar spot lesions. Our results show that P. maydis is deficient in inorganic nitrogen utilization, is likely heterothallic, and encodes for significantly more protein-coding genes, including secreted enzymes and effectors, than previous determined. Furthermore, our expression analysis suggests that, following primary tar spot lesion formation, P. maydis might reroute carbon flux away from DNA replication and cell division pathways and towards pathways previously implicated in having significant roles in pathogenicity, such as autophagy and secretion. Together, our results identified several highly expressed unique secreted factors that likely contribute to host recognition and subsequent infection, greatly increasing our knowledge of the biological capacity of P. maydis, which have much broader implications for mitigating tar spot of corn. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Joshua S MacCready
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Emily M Roggenkamp
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Kristi Gdanetz
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
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2
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Regulator of G Protein Signaling Contributes to the Development and Aflatoxin Biosynthesis in Aspergillus flavus through the Regulation of Gα Activity. Appl Environ Microbiol 2022; 88:e0024422. [PMID: 35638847 PMCID: PMC9238415 DOI: 10.1128/aem.00244-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G-proteins play crucial roles in growth, asexual development, and pathogenicity of fungi. The regulator of G-protein signaling (RGS) proteins function as negative regulators of the G proteins to control the activities of GTPase in Gα subunits. In this study, we functionally characterized the six RGS proteins (i.e., RgsA, RgsB, RgsC, RgsD, RgsE, and FlbA) in the pathogenic fungus Aspergillus flavus. All the aforementioned RGS proteins were also found to be functionally different in conidiation, aflatoxin (AF) biosynthesis, and pathogenicity in A. flavus. Apart from FlbA, all other RGS proteins play a negative role in regulating both the synthesis of cyclic AMP (cAMP) and the activation of protein kinase A (PKA). Additionally, we also found that although RgsA and RgsE play a negative role in regulating the FadA-cAMP/PKA pathway, they function distinctly in aflatoxin biosynthesis. Similarly, RgsC is important for aflatoxin biosynthesis by negatively regulating the GanA-cAMP/PKA pathway. PkaA, which is the cAMP-dependent protein kinase catalytic subunit, also showed crucial influences on A. flavus phenotypes. Overall, our results demonstrated that RGS proteins play multiple roles in the development, pathogenicity, and AF biosynthesis in A. flavus through the regulation of Gα subunits and cAMP-PKA signals. IMPORTANCE RGS proteins, as crucial regulators of the G protein signaling pathway, are widely distributed in fungi, while little is known about their roles in Aspergillus flavus development and aflatoxin. In this study, we identified six RGS proteins in A. flavus and revealed that these proteins have important functions in the regulation of conidia, sclerotia, and aflatoxin formation. Our findings provide evidence that the RGS proteins function upstream of cAMP-PKA signaling by interacting with the Gα subunits (GanA and FadA). This study provides valuable information for controlling the contamination of A. flavus and mycotoxins produced by this fungus in pre- and postharvest of agricultural crops.
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Yang K, Tian J, Keller NP. Post-translational modifications drive secondary metabolite biosynthesis in Aspergillus: a review. Environ Microbiol 2022; 24:2857-2881. [PMID: 35645150 PMCID: PMC9545273 DOI: 10.1111/1462-2920.16034] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 12/26/2022]
Abstract
Post‐translational modifications (PTMs) are important for protein function and regulate multiple cellular processes and secondary metabolites (SMs) in fungi. Aspergillus species belong to a genus renown for an abundance of bioactive secondary metabolites, many important as toxins, pharmaceuticals and in industrial production. The genes required for secondary metabolites are typically co‐localized in biosynthetic gene clusters (BGCs), which often localize in heterochromatic regions of genome and are ‘turned off’ under laboratory condition. Efforts have been made to ‘turn on’ these BGCs by genetic manipulation of histone modifications, which could convert the heterochromatic structure to euchromatin. Additionally, non‐histone PTMs also play critical roles in the regulation of secondary metabolism. In this review, we collate the known roles of epigenetic and PTMs on Aspergillus SM production. We also summarize the proteomics approaches and bioinformatics tools for PTM identification and prediction and provide future perspectives on the emerging roles of PTM on regulation of SM biosynthesis in Aspergillus and other fungi.
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Affiliation(s)
- Kunlong Yang
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China.,Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
| | - Jun Tian
- School of Life Science, Jiangsu Normal University, Xuzhou, 221116, Jiangsu Province, People's Republic of China
| | - Nancy P Keller
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53705, USA
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Yang K, Geng Q, Luo Y, Xie R, Sun T, Wang Z, Qin L, Zhao W, Liu M, Li Y, Tian J. Dysfunction of FadA-cAMP signalling decreases Aspergillus flavus resistance to antimicrobial natural preservative Perillaldehyde and AFB1 biosynthesis. Environ Microbiol 2022; 24:1590-1607. [PMID: 35194912 DOI: 10.1111/1462-2920.15940] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 02/09/2022] [Accepted: 02/12/2022] [Indexed: 01/02/2023]
Abstract
Aspergillus flavus is an opportunistic fungal pathogen that colonizes agriculture crops with aflatoxin contamination. We found that Perillaldehyde (PAE) effectively inhibited A. flavus viability and aflatoxin production by inducing excess reactive oxygen species (ROS). Transcriptome analysis indicated that the Gα protein FadA was significantly induced by PAE. Functional characterization of FadA showed it is important for asexual development and aflatoxin biosynthesis by regulation of cAMP-PKA signalling. The ΔfadA mutant was more sensitive to PAE, while ΔpdeL and ΔpdeH mutants can tolerate excess PAE compared to wild-type A. flavus. Further RNA-sequence analysis showed that fadA was important for expression of genes involved in oxidation-reduction and cellular metabolism. The flow cytometry and fluorescence microscopy demonstrated that ΔfadA accumulated more concentration of ROS in cells, and the transcriptome data indicated that genes involved in ROS scavenging were downregulated in ΔfadA mutant. We further found that FadA participated in regulating response to extracellular environmental stresses by increasing phosphorylation levels of MAPK Kinase Slt2 and Hog1. Overall, our results indicated that FadA signalling engages in mycotoxin production and A. flavus resistance to antimicrobial PAE, which provide valuable information for controlling this fungus and AF biosynthesis in pre- and postharvest of agricultural crops.
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Affiliation(s)
- Kunlong Yang
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Qingru Geng
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Yue Luo
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Rui Xie
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Tongzheng Sun
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Zhen Wang
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Ling Qin
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Wei Zhao
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Man Liu
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Yongxin Li
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
| | - Jun Tian
- School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, China
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Yu PL, Rollins JA. The cAMP-dependent protein kinase A pathway perturbs autophagy and plays important roles in development and virulence of Sclerotinia sclerotiorum. Fungal Biol 2022; 126:20-34. [DOI: 10.1016/j.funbio.2021.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 09/21/2021] [Accepted: 09/29/2021] [Indexed: 01/15/2023]
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Comparative Characterization of G Protein α Subunits in Aspergillus fumigatus. Pathogens 2020; 9:pathogens9040272. [PMID: 32283604 PMCID: PMC7238038 DOI: 10.3390/pathogens9040272] [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: 02/12/2020] [Revised: 04/03/2020] [Accepted: 04/03/2020] [Indexed: 12/24/2022] Open
Abstract
Trimeric G proteins play a central role in the G protein signaling in filamentous fungi and Gα subunits are the major component of trimeric G proteins. In this study, we characterize three Gα subunits in the human pathogen Aspergillus fumigatus. While the deletion of gpaB and ganA led to reduced colony growth, the growth of the ΔgpaA strain was increased in minimal media. The germination rate, conidiation, and mRNA expression of key asexual development regulators were significantly decreased by the loss of gpaB. In contrast, the deletion of gpaA resulted in increased conidiation and mRNA expression levels of key asexual regulators. The deletion of gpaB caused a reduction in conidial tolerance against H2O2, but not in paraquat (PQ). Moreover, the ΔgpaB mutant showed enhanced susceptibility against membrane targeting azole antifungal drugs and reduced production of gliotoxin (GT). The protein kinase A (PKA) activity of the ΔganA strain was severely decreased and protein kinase C (PKC) activity was detected all strains at similar levels, indicating that all G protein α subunits of A. fumigatus may be a component of the cAMP/PKA signaling pathway and appear to possess the PKC signaling pathway as an alternative backup pathway to compensate for PKA depletion. Collectively, the three Gα subunits regulate growth, germination, asexual development, resistance to oxidative stress, and GT production differently via the PKA or PKC signaling pathway. The function of GanA of A. fumigatus was elucidated for the first time.
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Patiño-Medina JA, Reyes-Mares NY, Valle-Maldonado MI, Jácome-Galarza IE, Pérez-Arques C, Nuñez-Anita RE, Campos-García J, Anaya-Martínez V, Ortiz-Alvarado R, Ramírez-Díaz MI, Chan Lee S, Garre V, Meza-Carmen V. Heterotrimeric G-alpha subunits Gpa11 and Gpa12 define a transduction pathway that control spore size and virulence in Mucor circinelloides. PLoS One 2019; 14:e0226682. [PMID: 31887194 PMCID: PMC6936849 DOI: 10.1371/journal.pone.0226682] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 12/03/2019] [Indexed: 02/07/2023] Open
Abstract
Mucor circinelloides is one of the causal agents of mucormycosis, an emerging and high mortality rate fungal infection produced by asexual spores (sporangiospores) of fungi that belong to the order Mucorales. M. circinelloides has served as a model genetic system to understand the virulence mechanism of this infection. Although the G-protein signaling cascade plays crucial roles in virulence in many pathogenic fungi, its roles in Mucorales are yet to be elucidated. Previous study found that sporangiospore size and calcineurin are related to the virulence in Mucor, in which larger spores are more virulent in an animal mucormycosis model and loss of a calcineurin A catalytic subunit CnaA results in larger spore production and virulent phenotype. The M. circinelloides genome is known to harbor twelve gpa (gpa1 to gpa12) encoding G-protein alpha subunits and the transcripts of the gpa11 and gpa12 comprise nearly 72% of all twelve gpa genes transcript in spores. In this study we demonstrated that loss of function of Gpa11 and Gpa12 led to larger spore size associated with reduced activation of the calcineurin pathway. Interestingly, we found lower levels of the cnaA mRNAs in sporangiospores from the Δgpa12 and double Δgpa11/Δgpa12 mutant strains compared to wild-type and the ΔcnaA mutant had significantly lower gpa11 and gpa12 mRNA levels compared to wild-type. However, in contrast to the high virulence showed by the large spores of ΔcnaA, the spores from Δgpa11/Δgpa12 were avirulent and produced lower tissue invasion and cellular damage, suggesting that the gpa11 and gpa12 define a signal pathway with two branches. One of the branches controls spore size through regulation of calcineurin pathway, whereas virulences is controlled by an independent pathway. This virulence-related regulatory pathway could control the expression of genes involved in cellular responses important for virulence, since sporangiospores of Δgpa11/Δgpa12 were less resistant to oxidative stress and phagocytosis by macrophages than the ΔcnaA and wild-type strains. The characterization of this pathway could contribute to decipher the signals and mechanism used by Mucorales to produce mucormycosis.
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Affiliation(s)
- J. Alberto Patiño-Medina
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
| | - Nancy Y. Reyes-Mares
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
| | - Marco I. Valle-Maldonado
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
| | - Irvin E. Jácome-Galarza
- Departamento de Biología Molecular, Laboratorio Estatal de Salud Pública del Estado de Michoacán, Morelia, Michoacán, México
| | - Carlos Pérez-Arques
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, España
| | - Rosa E. Nuñez-Anita
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás Hidalgo, Morelia, Michoacán, Mexico
| | - Jesús Campos-García
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
| | - Verónica Anaya-Martínez
- Facultad de Ciencias de la Salud, Universidad Anáhuac, Naucalpan de Juarez, Estado de México, México
| | - Rafael Ortiz-Alvarado
- Facultad de Químico Farmacobiología, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacan, México
| | - Martha I. Ramírez-Díaz
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
| | - Soo Chan Lee
- Department of Biology, South Texas Center of Emerging Infectious Diseases (STCEID), University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Victoriano Garre
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, España
| | - Víctor Meza-Carmen
- Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia, Michoacán, México
- * E-mail:
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Lan H, Wu L, Sun R, Keller NP, Yang K, Ye L, He S, Zhang F, Wang S. The HosA Histone Deacetylase Regulates Aflatoxin Biosynthesis Through Direct Regulation of Aflatoxin Cluster Genes. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1210-1228. [PMID: 30986121 DOI: 10.1094/mpmi-01-19-0033-r] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Histone deacetylases (HDACs) always function as corepressors and sometimes as coactivators in the regulation of fungal development and secondary metabolite production. However, the mechanism through which HDACs play positive roles in secondary metabolite production is still unknown. Here, classical HDAC enzymes were identified and analyzed in Aspergillus flavus, a fungus that produces one of the most carcinogenic secondary metabolites, aflatoxin B1 (AFB1). Characterization of the HDACs revealed that a class I family HDAC, HosA, played crucial roles in growth, reproduction, the oxidative stress response, AFB1 biosynthesis, and pathogenicity. To a lesser extent, a class II family HDAC, HdaA, was also involved in sclerotia formation and AFB1 biosynthesis. An in vitro analysis of HosA revealed that its HDAC activity was considerably diminished at nanomolar concentrations of trichostatin A. Notably, chromatin immunoprecipitation experiments indicated that HosA bound directly to AFB1 biosynthesis cluster genes to regulate their expression. Finally, we found that a transcriptional regulator, SinA, interacts with HosA to regulate fungal development and AFB1 biosynthesis. Overall, our results reveal a novel mechanism by which classical HDACs mediate the induction of secondary metabolite genes in fungi.
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Affiliation(s)
- Huahui Lan
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lianghuan Wu
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Ruilin Sun
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Nancy P Keller
- Departments of Bacteriology, Medical Microbiology, and Immunology, University of Wisconsin-Madison, Madison, WI, U.S.A
| | - Kunlong Yang
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Liuqing Ye
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shuibin He
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Feng Zhang
- Fujian Key Laboratory of Pathogenic Fungi Mycotoxins of Fujian Province, 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 Mycotoxins of Fujian Province, 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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Yang K, Liu Y, Wang S, Wu L, Xie R, Lan H, Fasoyin OE, Wang Y, Wang S. Cyclase-Associated Protein Cap with Multiple Domains Contributes to Mycotoxin Biosynthesis and Fungal Virulence in Aspergillus flavus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:4200-4213. [PMID: 30916945 DOI: 10.1021/acs.jafc.8b07115] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In Aspergillus, the cyclic adenosine monophosphate (cAMP) signaling modulates asexual development and mycotoxin biosynthesis. Here, we characterize the cyclase-associated protein Cap in the pathogenic fungus Aspergillus flauvs. The cap disruption mutant exhibited dramatic reduction in hyphal growth, conidiation, and spore germination, while an enhanced production of the sclerotia was observed in this mutant. Importantly, the cap gene was found to be important for mycotoxin biosynthesis and virulence. The domain deletion study demonstrated that each domain played an important role for the Cap protein in regulating cAMP/protein kinase A (PKA) signaling, while only P1 and CARP domains were essential for the full function of Cap. The phosphorylation of Cap at S35 was identified in A. flavus, which was found to play a negligible role for the function of Cap. Overall, our results indicated that Cap with multiple domains engages in mycotoxin production and fungal pathogenicity, which could be designed as potential control targets for preventing this fungal pathogen.
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Affiliation(s)
- Kunlong Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
- School of Life Science , Jiangsu Normal University , Xuzhou , Jiangsu 221116 , People's Republic of China
| | - Yinghang Liu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
- State Key Laboratory of Microbial Technology , Shandong University , Jinan , Shandong 250100 , People's Republic of China
| | - Sen Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
| | - Lianghuan Wu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
| | - Rui Xie
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
| | - Huahui Lan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
| | - Opemipo Esther Fasoyin
- Biotechnology Research Institute , Chinese Academy of Agricultural Sciences , 12 Zhongguancun South Street , Beijing 100081 , People's Republic of China
| | - Yu Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences , Fujian Agriculture and Forestry University , Fuzhou , Fujian 350002 , People's Republic of China
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10
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Lan H, Wu L, Fan K, Sun R, Yang G, Zhang F, Yang K, Lin X, Chen Y, Tian J, Wang S. Set3 Is Required for Asexual Development, Aflatoxin Biosynthesis, and Fungal Virulence in Aspergillus flavus. Front Microbiol 2019; 10:530. [PMID: 31001207 PMCID: PMC6455067 DOI: 10.3389/fmicb.2019.00530] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/01/2019] [Indexed: 12/30/2022] Open
Abstract
Aspergillus flavus is an opportunistic pathogenic fungus for both plant and animal that produces carcinogenic toxins termed aflatoxins (AFs). To identify possible genetic targets to reduce AF contamination, in this study, we have characterized a novel A. flavus Set3, and it shares sequence homology with the yeast protein Set3. The set3 deletion mutants present no difference in growth rate but alterations in asexual development and secondary metabolite production when compared to the A. flavus wild type. Specifically, deletion of set3 gene decreases conidiophore formation and conidial production through downregulating expression of brlA and abaA genes. In addition, normal levels of set3 are required for sclerotial development and expression of sclerotia-related genes nsdC and sclR. Further analyses demonstrated that Set3 negatively regulates AF production as well as the concomitant expression of genes in the AF gene cluster. Importantly, our results also display that A. flavus Set3 is involved in crop kernel colonization. Taking together, these results reveal that a novel Set3 plays crucial roles in morphological development, secondary metabolism, and fungal virulence in A. flavus.
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Affiliation(s)
- Huahui Lan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lianghuan Wu
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kun Fan
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Ruilin Sun
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guang Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and 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, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kunlong Yang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,College of Life Science, Jiangsu Normal University, Xuzhou, China
| | - Xiaolu Lin
- Longyan City Corporation of Fujian Tobacco Corporation, Longyan, China
| | - Yanhong Chen
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jun Tian
- College of Life Science, Jiangsu Normal University, Xuzhou, China
| | - Shihua Wang
- Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province, Key Laboratory of Biopesticide and Chemical Biology of Education Ministry, and School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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11
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Wirth S, Kunert M, Ahrens LM, Krause K, Broska S, Paetz C, Kniemeyer O, Jung EM, Boland W, Kothe E. The regulator of G-protein signalling Thn1 links pheromone response to volatile production in Schizophyllum commune. Environ Microbiol 2018; 20:3684-3699. [PMID: 30062773 DOI: 10.1111/1462-2920.14369] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 07/13/2018] [Accepted: 07/27/2018] [Indexed: 01/07/2023]
Abstract
The regulator of G-protein signalling, Thn1, is involved in sexual development through pheromone signalling in the mushroom forming basidiomycete Schizophyllum commune affecting hyphal morphology and mating interactions. Thn1 plays a key role in coordinating sesquiterpene production, pheromone response and sexual development. The gene thn1 is transcriptionally regulated in response to mating with a role in clamp cell development and hydrophobin gene transcription. Further, it negatively regulates cAMP signalling and secondary metabolism. Disruption of thn1 affects dikaryotization by reducing clamp fusion and development with predominant non-fused pseudoclamps. Enhanced protein kinase A (PKA) activities in Δthn1 strains indicate that Thn1 regulates pheromone signalling by de-activating G-protein α subunits, which control cAMP-dependent PKA. The repressed formation of aerial hyphae could be linked to a reduced metabolic activity and to a transcriptional down-regulation of hyd6 and sc3 hydrophobin genes. Thn1 was also shown to be necessary for the biosynthesis of sesquiterpenes and an altered spectrum of sesquiterpenes in Δthn1 is linked to transcriptional up-regulation of biosynthesis genes. Proteome analysis indicated changes in cytoskeletal structure affecting actin localization, linking the major regulator Thn1 to growth and development of S. commune. The results support a role for Thn1 in G-protein signalling connecting development and secondary metabolism.
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Affiliation(s)
- Sophia Wirth
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
| | - Maritta Kunert
- Max Planck Institute for Chemical Ecology, Bioorganic Chemistry, Hans-Knöll-Straße 8, 07745, Jena, Germany
| | - Lisa-Marija Ahrens
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
| | - Katrin Krause
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
| | - Selina Broska
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
| | - Christian Paetz
- Max Planck Institute for Chemical Ecology, Bioorganic Chemistry, Hans-Knöll-Straße 8, 07745, Jena, Germany
| | - Olaf Kniemeyer
- Leibnitz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Molecular and Applied Microbiology, Adolf-Reichwein-Straße 23, 07745, Jena, Germany
| | - Elke-Martina Jung
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
| | - Wilhelm Boland
- Max Planck Institute for Chemical Ecology, Bioorganic Chemistry, Hans-Knöll-Straße 8, 07745, Jena, Germany
| | - Erika Kothe
- Friedrich Schiller University Jena, Institute of Microbiology, Microbial Communication, Neugasse 25, 07743, Jena, Germany
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12
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Liu Y, Yang K, Qin Q, Lin G, Hu T, Xu Z, Wang S. G Protein α Subunit GpaB is Required for Asexual Development, Aflatoxin Biosynthesis and Pathogenicity by Regulating cAMP Signaling in Aspergillus flavus. Toxins (Basel) 2018. [PMID: 29534423 PMCID: PMC5869405 DOI: 10.3390/toxins10030117] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The heterotrimeric G proteins are critical for signal transduction and function in numerous biological processes including vegetative growth, asexual development and fungal virulence in fungi. Here, we identified four G protein alpha subunits (GanA, GpaB, FadA and GaoC) in the notorious Aflatoxin-producing fungus Aspergillus flavus. GanA, GpaB and FadA have homologues in other fungal species, while GaoC is a novel one. Here, we showed that the loss function of gpaB displayed a defect in conidiophore formation and considerably reduced expression levels of conidia-specific genes brlA and abaA. A decreased viability of cell wall integrity stress and oxidative stress were also found in the ∆gpaB mutant. More importantly, aflatoxin (AF) biosynthesis and infection on crop seeds were severely impaired in the gpaB-deficient mutant. Further analyses demonstrated that the intracellular cAMP levels significantly reduced in the gpaB-deficient mutant compared to wildtype strains. Additionally, an alteration of PKA activities in the ∆gpaB mutant was also found. Overall, our results indicated that GpaB played diverse roles in asexual sporulation, AF biosynthesis and virulence by regulating cAMP signaling in Aspergillus flavus.
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Affiliation(s)
- Yinghang 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.
| | - Kunlong 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.
| | - Qiuping Qin
- 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 Anjie Medical Data Technology Co. Ltd., Xiamen 361115, China.
| | - Guinan 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.
| | - Tianran 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.
| | - Zhangling Xu
- 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.
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13
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Yin T, Zhang Q, Wang J, Liu H, Wang C, Xu J, Jiang C. The cyclase-associated protein FgCap1 has both protein kinase A-dependent and -independent functions during deoxynivalenol production and plant infection in Fusarium graminearum. MOLECULAR PLANT PATHOLOGY 2018; 19:552-563. [PMID: 28142217 PMCID: PMC6638064 DOI: 10.1111/mpp.12540] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/21/2017] [Accepted: 01/23/2017] [Indexed: 05/25/2023]
Abstract
Fusarium graminearum is a causal agent of wheat scab and a producer of the trichothecene mycotoxin deoxynivalenol (DON). The expression of trichothecene biosynthesis (TRI) genes and DON production are mainly regulated by the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) pathway and two pathway-specific transcription factors (TRI6 and TRI10). Interestingly, deletion mutants of TRI6 show reduced expression of several components of cAMP signalling, including the FgCAP1 adenylate-binding protein gene that has not been functionally characterized in F. graminearum. In this study, we show that FgCap1 interacts with Fac1 adenylate cyclase and that deletion of FgCAP1 reduces the intracellular cAMP level and PKA activity. The Fgcap1 deletion mutant is defective in vegetative growth, conidiogenesis and plant infection. It also shows significantly reduced DON production and TRI gene expression, which can be suppressed by exogenous cAMP, indicating a PKA-dependent regulation of DON biosynthesis by FgCap1. The wild-type, but not tri6 mutant, shows increased levels of intracellular cAMP and FgCAP1 expression under DON-producing conditions. Furthermore, the promoter of FgCAP1 contains one putative Tri6-binding site that is important for its function during DON biosynthesis, but is dispensable for hyphal growth, conidiogenesis and pathogenesis. In addition, FgCap1 shows an actin-like localization to the cortical patches at the apical region of hyphal tips. Phosphorylation of FgCap1 at S353 was identified by phosphoproteomics analysis. The S353A mutation in FgCAP1 has no effect on its functions during vegetative growth, conidiation and DON production. However, expression of the FgCAP1S353A allele fails to complement the defects of the Fgcap1 mutant in plant infection, indicating the importance of the phosphorylation of FgCap1 at S353 during pathogenesis. Taken together, our results suggest that FgCAP1 is involved in the regulation of DON production via cAMP signalling and subjected to a feedback regulation by TRI6, but the phosphorylation of FgCap1 at S353 is probably unrelated to the cAMP-PKA pathway because the S353A mutation only affects plant infection.
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Affiliation(s)
- Tao Yin
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
| | - Qiang Zhang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Jianhua Wang
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
- Institute for Agri‐food Standards and Testing TechnologyShanghai Academy of Agricultural SciencesShanghai201403China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Chenfang Wang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Jin‐Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
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14
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Fountain JC, Koh J, Yang L, Pandey MK, Nayak SN, Bajaj P, Zhuang WJ, Chen ZY, Kemerait RC, Lee RD, Chen S, Varshney RK, Guo B. Proteome analysis of Aspergillus flavus isolate-specific responses to oxidative stress in relationship to aflatoxin production capability. Sci Rep 2018; 8:3430. [PMID: 29467403 PMCID: PMC5821837 DOI: 10.1038/s41598-018-21653-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/03/2018] [Indexed: 12/24/2022] Open
Abstract
Aspergillus flavus is an opportunistic pathogen of plants such as maize and peanut under conducive conditions such as drought stress resulting in significant aflatoxin production. Drought-associated oxidative stress also exacerbates aflatoxin production by A. flavus. The objectives of this study were to use proteomics to provide insights into the pathogen responses to H2O2-derived oxidative stress, and to identify potential biomarkers and targets for host resistance breeding. Three isolates, AF13, NRRL3357, and K54A with high, moderate, and no aflatoxin production, were cultured in medium supplemented with varying levels of H2O2, and examined using an iTRAQ (Isobaric Tags for Relative and Absolute Quantification) approach. Overall, 1,173 proteins were identified and 220 were differentially expressed (DEPs). Observed DEPs encompassed metabolic pathways including antioxidants, carbohydrates, pathogenicity, and secondary metabolism. Increased lytic enzyme, secondary metabolite, and developmental pathway expression in AF13 was correlated with oxidative stress tolerance, likely assisting in plant infection and microbial competition. Elevated expression of energy and cellular component production in NRRL3357 and K54A implies a focus on oxidative damage remediation. These trends explain isolate-to-isolate variation in oxidative stress tolerance and provide insights into mechanisms relevant to host plant interactions under drought stress allowing for more targeted efforts in host resistance research.
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Affiliation(s)
- Jake C Fountain
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.,Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Jin Koh
- Department of Biology, Genetics Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, USA
| | - Liming Yang
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA.,USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.,College of Biology and Environmental Science, Nanjing Forestry University, Nanjing, China
| | - Manish K Pandey
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Spurthi N Nayak
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Prasad Bajaj
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Wei-Jian Zhuang
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Zhi-Yuan Chen
- Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, LA, USA
| | - Robert C Kemerait
- Department of Plant Pathology, University of Georgia, Tifton, GA, USA
| | - R Dewey Lee
- Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA
| | - Sixue Chen
- Department of Biology, Genetics Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, USA
| | - Rajeev K Varshney
- Center of Excellence in Genomics & Systems Biology, International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Telangana, India
| | - Baozhu Guo
- USDA-ARS Crop Protection and Management Research Unit, Tifton, GA, USA.
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15
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Wee J, Hong SY, Roze LV, Day DM, Chanda A, Linz JE. The Fungal bZIP Transcription Factor AtfB Controls Virulence-Associated Processes in Aspergillus parasiticus. Toxins (Basel) 2017; 9:toxins9090287. [PMID: 28926946 PMCID: PMC5618220 DOI: 10.3390/toxins9090287] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 08/24/2017] [Accepted: 09/07/2017] [Indexed: 12/14/2022] Open
Abstract
Fungal basic leucine zipper (bZIP) transcription factors mediate responses to oxidative stress. The ability to regulate stress response pathways in Aspergillus spp. was postulated to be an important virulence-associated cellular process, because it helps establish infection in humans, plants, and animals. Previous studies have demonstrated that the fungal transcription factor AtfB encodes a protein that is associated with resistance to oxidative stress in asexual conidiospores, and AtfB binds to the promoters of several stress response genes. Here, we conducted a gene silencing of AtfB in Aspergillus parasiticus, a well-characterized fungal pathogen of plants, animals, and humans that produces the secondary metabolite and carcinogen aflatoxin, in order to determine the mechanisms by which AtfB contributes to virulence. We show that AtfB silencing results in a decrease in aflatoxin enzyme levels, the down-regulation of aflatoxin accumulation, and impaired conidiospore development in AtfB-silenced strains. This observation is supported by a decrease of AtfB protein levels, and the down-regulation of many genes in the aflatoxin cluster, as well as genes involved in secondary metabolism and conidiospore development. Global expression analysis (RNA Seq) demonstrated that AtfB functionally links oxidative stress response pathways to a broader and novel subset of target genes involved in cellular defense, as well as in actin and cytoskeleton arrangement/transport. Thus, AtfB regulates the genes involved in development, stress response, and secondary metabolism in A. parasiticus. We propose that the bZIP regulatory circuit controlled by AtfB provides a large number of excellent cellular targets to reduce fungal virulence. More importantly, understanding key players that are crucial to initiate the cellular response to oxidative stress will enable better control over its detrimental impacts on humans.
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Affiliation(s)
- Josephine Wee
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, USA.
| | - Sung-Yong Hong
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
| | - Ludmila V Roze
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.
| | - Devin M Day
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
| | - Anindya Chanda
- Department of Environmental Health Sciences, University of South Carolina, Columbia, SC 29208, USA.
| | - John E Linz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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16
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Yang K, Liu Y, Liang L, Li Z, Qin Q, Nie X, Wang S. The high-affinity phosphodiesterase PdeH regulates development and aflatoxin biosynthesis in Aspergillus flavus. Fungal Genet Biol 2017; 101:7-19. [PMID: 28212851 DOI: 10.1016/j.fgb.2017.02.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/08/2017] [Indexed: 01/25/2023]
Abstract
Cyclic AMP signaling controls a range of physiological processes in response to extracellular stimuli in organisms. Among the signaling cascades, cAMP, as a second messenger, is orchestrated by adenylate cyclase (biosynthesis) and cAMP phosphodiesterases (PDEs) (hydrolysis). In this study, we investigated the function of the high-affinity (PdeH) and low-affinity (PdeL) cAMP phosphodiesterase from the carcinogenic aflatoxin producing fungus Aspergillus flavus, and found that instead of PdeL, inactivation of PdeH exhibited a reduction in conidiation and sclerotia formation. However, the ΔpdeL/ΔpdeH mutant exhibited an enhanced phenotype defects, a similar phenotype defects to wild-type strain treated with exogenous cAMP. The activation of PKA activity was inhibited in the ΔpdeH or ΔpdeL/ΔpdeH mutant, both of whom exhibited increasing AF production. Further analysis by qRT-PCR revealed that pdeH had a high transcriptional level compared to pdeL in wild-type strain, and affected pdeL transcription. Green fluorescent protein tagging at the C-terminus of PDEs showed that PdeH-GFP is broadly compartmentalized in the cytosol, while PdeL-GFP localized mainly to the nucleus. Overall, our results indicated that PdeH plays a major role, but has overlapping function with PdeL, in vegetative growth, development and AF biosynthesis in A. flavus.
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Affiliation(s)
- Kunlong 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
| | - Yinghang 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
| | - Linlin Liang
- 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
| | - Zhenguo 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
| | - Qiuping Qin
- 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
| | - Xinyi Nie
- 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.
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17
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Lee JW, Roze LV, Linz JE. Evidence that a wortmannin-sensitive signal transduction pathway regulates aflatoxin biosynthesis. Mycologia 2017. [DOI: 10.1080/15572536.2007.11832550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Joo-Won Lee
- Department of Pharmacology, Institute of Biomedical Science, Hanyang University, Seoul, South Korea
| | - Ludmila V. Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan
| | - John E. Linz
- Department of Food Science and Human Nutrition, Department of Microbiology and Molecular Genetics, National Food Safety and Toxicology Center, 234B GM Trout Building, Michigan State University, East Lansing, Michigan 48823
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18
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Yang K, Qin Q, Liu Y, Zhang L, Liang L, Lan H, Chen C, You Y, Zhang F, Wang S. Adenylate Cyclase AcyA Regulates Development, Aflatoxin Biosynthesis and Fungal Virulence in Aspergillus flavus. Front Cell Infect Microbiol 2016; 6:190. [PMID: 28066725 PMCID: PMC5175447 DOI: 10.3389/fcimb.2016.00190] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/05/2016] [Indexed: 01/27/2023] Open
Abstract
Aspergillus flavus is one of the most important opportunistic pathogens of crops and animals. The carcinogenic mycotoxin, aflatoxins produced by this pathogen cause a health problem to human and animals. Since cyclic AMP signaling controls a range of physiological processes, like fungal development and infection when responding to extracellular stimuli in fungal pathogens, in this study, we investigated the function of adenylate cyclase, a core component of cAMP signaling, in aflatoxins biosynthesis and virulence on plant seeds in A. flavus. A gene replacement strategy was used to generate the deletion mutant of acyA that encodes the adenylate cyclase. Severe defects in fungal growth, sporulation and sclerotia formation were observed in the acyA deletion mutant. The defect in radical growth could be partially rescued by exogenous cAMP analog. The acyA mutant was also significantly reduced in aflatoxins production and virulence. Similar to the former studies in other fungi, The acyA mutant showed enhancing tolerance to oxidative stress, but more sensitive to heat stress. Overall, the pleiotropic defects of the acyA deletion mutant indicates that the cAMP-PKA pathway is involved in fungal development, aflatoxins biosynthesis and plant seed invasion in A. flavus.
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Affiliation(s)
- Kunlong 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, China
| | - Qiuping Qin
- 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, China
| | - Yinghang 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, China
| | - Limei 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, China
| | - Linlin Liang
- 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, China
| | - Huahui Lan
- 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, China
| | - Chihao Chen
- 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, China
| | - Yunchao You
- 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, China
| | - Feng 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, 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, China
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19
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Macheleidt J, Mattern DJ, Fischer J, Netzker T, Weber J, Schroeckh V, Valiante V, Brakhage AA. Regulation and Role of Fungal Secondary Metabolites. Annu Rev Genet 2016; 50:371-392. [DOI: 10.1146/annurev-genet-120215-035203] [Citation(s) in RCA: 219] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Juliane Macheleidt
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
| | - Derek J. Mattern
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
- Institute for Microbiology, Friedrich Schiller University Jena, 07737 Jena, Germany
| | - Juliane Fischer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
- Institute for Microbiology, Friedrich Schiller University Jena, 07737 Jena, Germany
| | - Tina Netzker
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
- Institute for Microbiology, Friedrich Schiller University Jena, 07737 Jena, Germany
| | - Jakob Weber
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
- Institute for Microbiology, Friedrich Schiller University Jena, 07737 Jena, Germany
| | - Volker Schroeckh
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
| | - Vito Valiante
- Research Group Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology (HKI), 07745 Jena, Germany;
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), 07745 Jena, Germany; , , , , , ,
- Institute for Microbiology, Friedrich Schiller University Jena, 07737 Jena, Germany
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20
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Wang Z, Jin K, Xia Y. Transcriptional analysis of the conidiation pattern shift of the entomopathogenic fungus Metarhizium acridum in response to different nutrients. BMC Genomics 2016; 17:586. [PMID: 27506833 PMCID: PMC4979188 DOI: 10.1186/s12864-016-2971-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/27/2016] [Indexed: 12/14/2022] Open
Abstract
Background Most fungi, including entomopathogenic fungi, have two different conidiation patterns, normal and microcycle conidiation, under different culture conditions, eg, in media containing different nutrients. However, the mechanisms underlying the conidiation pattern shift are poorly understood. Results In this study, Metarhizium acridum undergoing microcycle conidiation on sucrose yeast extract agar (SYA) medium shifted to normal conidiation when the medium was supplemented with sucrose, nitrate, or phosphate. By linking changes in nutrients with the conidiation pattern shift and transcriptional changes, we obtained conidiation pattern shift libraries by Solexa/Illumina deep-sequencing technology. A comparative analysis demonstrated that the expression of 137 genes was up-regulated during the shift to normal conidiation, while the expression of 436 genes was up-regulated at the microcycle conidiation stage. A comparison of subtractive libraries revealed that 83, 216, and 168 genes were related to sucrose-induced, nitrate-induced, and phosphate-induced conidiation pattern shifts, respectively. The expression of 217 genes whose expression was specific to microcycle conidiation was further analyzed by the gene expression profiling via multigene concatemers method using mRNA isolated from M. acridum grown on SYA and the four normal conidiation media. The expression of 142 genes was confirmed to be up-regulated on standard SYA medium. Of these 142 genes, 101 encode hypothetical proteins or proteins of unknown function, and only 41 genes encode proteins with putative functions. Of these 41 genes, 18 are related to cell growth, 10 are related to cell proliferation, three are related to the cell cycle, three are related to cell differentiation, two are related to cell wall synthesis, two are related to cell division, and seven have other functions. These results indicate that the conidiation pattern shift in M. acridum mainly results from changes in cell growth and proliferation. Conclusions The results indicate that M. acridum shifts conidiation pattern from microcycle conidiation to normal conidiation when there is increased sucrose, nitrate, or phosphate in the medium during microcycle conidiation. The regulation of conidiation patterning is a complex process involving the cell cycle and metabolism of M. acridum. This study provides essential information about the molecular mechanism of the induction of the conidiation pattern shift by single nutrients. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2971-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhenglong Wang
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400045, People's Republic of China.,Chongqing Engineering Research Center for Fungal Insecticide, Chongqing University, Chongqing, 400045, People's Republic of China.,Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing University, Chongqing, 400045, People's Republic of China
| | - Kai Jin
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400045, People's Republic of China.,Chongqing Engineering Research Center for Fungal Insecticide, Chongqing University, Chongqing, 400045, People's Republic of China.,Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing University, Chongqing, 400045, People's Republic of China
| | - Yuxian Xia
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing, 400045, People's Republic of China. .,Chongqing Engineering Research Center for Fungal Insecticide, Chongqing University, Chongqing, 400045, People's Republic of China. .,Key Laboratory of Gene Function and Regulation Technologies under Chongqing Municipal Education Commission, Chongqing University, Chongqing, 400045, People's Republic of China.
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Wee J, Day DM, Linz JE. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus. Toxins (Basel) 2016; 8:toxins8060171. [PMID: 27271668 PMCID: PMC4926138 DOI: 10.3390/toxins8060171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/25/2016] [Accepted: 05/27/2016] [Indexed: 11/16/2022] Open
Abstract
Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N′,N′-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin.
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Affiliation(s)
- Josephine Wee
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, USA.
| | - Devin M Day
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
| | - John E Linz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
- Center for Integrative Toxicology, Michigan State University, East Lansing, MI 48824, 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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23
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Mycoremediation with mycotoxin producers: a critical perspective. Appl Microbiol Biotechnol 2015; 100:17-29. [DOI: 10.1007/s00253-015-7032-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/08/2015] [Accepted: 09/10/2015] [Indexed: 12/18/2022]
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Abstract
G protein-coupled receptors (GPCRs) are transmembrane receptors that relay signals from the external environment inside the cell, allowing an organism to adapt to its surroundings. They are known to detect a vast array of ligands, including sugars, amino acids, pheromone peptides, nitrogen sources, oxylipins, and light. Despite their prevalence in fungal genomes, very little is known about the functions of filamentous fungal GPCRs. Here we present the first full-genome assessment of fungal GPCRs through characterization of null mutants of all 15 GPCRs encoded by the aflatoxin-producing fungus Aspergillus flavus. All strains were assessed for growth, development, ability to produce aflatoxin, and response to carbon sources, nitrogen sources, stress agents, and lipids. Most GPCR mutants were aberrant in one or more response processes, possibly indicative of cross talk in downstream signaling pathways. Interestingly, the biological defects of the mutants did not correspond with assignment to established GPCR classes; this is likely due to the paucity of data for characterized fungal GPCRs. Many of the GPCR transcripts were differentially regulated under various conditions as well. The data presented here provide an extensive overview of the full set of GPCRs encoded by A. flavus and provide a framework for analysis in other fungal species. Aspergillus flavus is an opportunistic pathogen of crops and animals, including humans, and it produces a carcinogenic toxin called aflatoxin. Because of this, A. flavus accounts for food shortages and economic losses in addition to sickness and death. Effective means of combating this pathogen are needed to mitigate its deleterious effects. G protein-coupled receptors (GPCRs) are often used as therapeutic targets due to their signal specificity, and it is estimated that half of all drugs target GPCRs. In fungi such as A. flavus, GPCRs are likely necessary for sensing the changes in the environment, including food sources, developmental signals, stress agents, and signals from other organisms. Therefore, elucidating their functions in A. flavus could identify ideal receptors against which to develop antagonists.
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Banerjee S, Gummadidala PM, Rima RA, Ahmed RU, Kenne GJ, Mitra C, Gomaa OM, Hill J, McFadden S, Banaszek N, Fayad R, Terejanu G, Chanda A. Quantitative acoustic contrast tomography reveals unique multiscale physical fluctuations during aflatoxin synthesis in Aspergillus parasiticus. Fungal Genet Biol 2014; 73:61-8. [PMID: 25312859 DOI: 10.1016/j.fgb.2014.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/01/2014] [Accepted: 10/06/2014] [Indexed: 01/14/2023]
Abstract
Fungal pathogens need regulated mechanical and morphological fine-tuning for pushing through substrates to meet their metabolic and functional needs. Currently very little is understood on how coordinated colony level morphomechanical modifications regulate their behavior. This is due to an absence of a method that can simultaneously map, quantify, and correlate global fluctuations in physical properties of the expanding fungal colonies. Here, we show that three-dimensional ultrasonic reflections upon decoding can render acoustic contrast tomographs that contain information on material property and morphology in the same time scale of one important phytopathogen, Aspergillus parasiticus, at multiple length scales. By quantitative analysis of the changes in acoustic signatures collected as the A. parasiticus colony expands with time, we further demonstrate that the pathogen displays unique acoustic signatures during synthesis and release of its hepatocarcinogenic secondary metabolite, aflatoxin, suggesting an involvement of a multiscale morphomechanical reorganization of the colony in this process. Our studies illustrate for the first time, the feasibility of generating in any invading cell population, four-dimensional maps of global physical properties, with minimal physical perturbation of the specimens. Our developed method that we term quantitative acoustic contrast tomography (Q-ACT), provides a novel diagnostic framework for the identification of in-cell molecular factors and discovery of small molecules that may modulate pathogen invasion in a host.
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Affiliation(s)
- Sourav Banerjee
- Integrated Material Assessment and Predictive Simulation Laboratory (i-MAPS), Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States.
| | - Phani M Gummadidala
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States
| | - Rowshan A Rima
- Integrated Material Assessment and Predictive Simulation Laboratory (i-MAPS), Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Riaz U Ahmed
- Integrated Material Assessment and Predictive Simulation Laboratory (i-MAPS), Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States
| | - Gabriel J Kenne
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States
| | - Chandrani Mitra
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States
| | - Ola M Gomaa
- Microbiology Department, National Center for Radiation Research and Technology, Cairo, Egypt
| | - Jasmine Hill
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States
| | - Sandra McFadden
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States
| | - Nora Banaszek
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States
| | - Raja Fayad
- Department of Exercise Science, Arnold School of Public Health University of South Carolina, Columbia, SC 29208, United States; Center for Colon Cancer Research, University of South Carolina, United States
| | - Gabriel Terejanu
- Department of Computer Science and Engineering, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States
| | - Anindya Chanda
- Laboratory of Fungal Pathogenesis and Secondary Metabolism, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States; Center for Uncertainty Driven Computational Biomechanics, University of South Carolina, Columbia, SC 29208, United States.
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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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Gomaa OM, El Nour SA. Aflatoxin inhibition in Aspergillus flavus for bioremediation purposes. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-013-0732-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Identification of metabolic pathways influenced by the G-protein coupled receptors GprB and GprD in Aspergillus nidulans. PLoS One 2013; 8:e62088. [PMID: 23658706 PMCID: PMC3641053 DOI: 10.1371/journal.pone.0062088] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/16/2013] [Indexed: 11/19/2022] Open
Abstract
Heterotrimeric G-protein-mediated signaling pathways play a pivotal role in transmembrane signaling in eukaryotes. Our main aim was to identify signaling pathways regulated by A. nidulans GprB and GprD G-protein coupled receptors (GPCRs). When these two null mutant strains were compared to the wild-type strain, the ΔgprB mutant showed an increased protein kinase A (PKA) activity while growing in glucose 1% and during starvation. In contrast, the ΔgprD has a much lower PKA activity upon starvation. Transcriptomics and 1H NMR-based metabolomics were performed on two single null mutants grown on glucose. We noted modulation in the expression of 11 secondary metabolism gene clusters when the ΔgprB and ΔgprD mutant strains were grown in 1% glucose. Several members of the sterigmatocystin-aflatoxin gene cluster presented down-regulation in both mutant strains. The genes of the NR-PKS monodictyphenone biosynthesis cluster had overall increased mRNA accumulation in ΔgprB, while in the ΔgprD mutant strain the genes had decreased mRNA accumulation. Principal component analysis of the metabolomic data demonstrated that there was a significant metabolite shift in the ΔgprD strain. The 1H NMR analysis revealed significant expression of essential amino acids with elevated levels in the ΔgprD strain, compared to the wild-type and ΔgprB strains. With the results, we demonstrated the differential expression of a variety of genes related mainly to secondary metabolism, sexual development, stress signaling, and amino acid metabolism. We propose that the absence of GPCRs triggered stress responses at the genetic level. The data suggested an intimate relationship among different G-protein coupled receptors, fine-tune regulation of secondary and amino acid metabolisms, and fungal development.
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Towards systems biology of mycotoxin regulation. Toxins (Basel) 2013; 5:675-82. [PMID: 23598563 PMCID: PMC3705286 DOI: 10.3390/toxins5040675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/22/2013] [Accepted: 04/10/2013] [Indexed: 11/16/2022] Open
Abstract
Systems biology is a scientific approach that integrates many scientific disciplines to develop a comprehensive understanding of biological phenomena, thus allowing the prediction and accurate simulation of complex biological behaviors. It may be presumptuous to write about toxin regulation at the level of systems biology, but the last decade of research is leading us closer than ever to this approach. Past research has delineated multiple levels of regulation in the pathways leading to the biosynthesis of secondary metabolites, including mycotoxins. At the top of this hierarchy, the global or master transcriptional regulators perceive various environmental cues such as climatic conditions, the availability of nutrients, and the developmental stages of the organism. Information accumulated from various inputs is integrated through a complex web of signalling networks to generate the eventual outcome. This review will focus on adapting techniques such as chemical and other genetic tools available in the model system Saccharomyces cerevisiae, to disentangle the various biological networks involved in the biosynthesis of mycotoxins in the Fusarium spp.
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The putative guanine nucleotide exchange factor RicA mediates upstream signaling for growth and development in Aspergillus. EUKARYOTIC CELL 2012; 11:1399-412. [PMID: 23002107 DOI: 10.1128/ec.00255-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Heterotrimeric G proteins (G proteins) govern growth, development, and secondary metabolism in various fungi. Here, we characterized ricA, which encodes a putative GDP/GTP exchange factor for G proteins in the model fungus Aspergillus nidulans and the opportunistic human pathogen Aspergillus fumigatus. In both species, ricA mRNA accumulates during vegetative growth and early developmental phases, but it is not present in spores. The deletion of ricA results in severely impaired colony growth and the total (for A. nidulans) or near (for A. fumigatus) absence of asexual sporulation (conidiation). The overexpression (OE) of the A. fumigatus ricA gene (AfricA) restores growth and conidiation in the ΔAnricA mutant to some extent, indicating partial conservation of RicA function in Aspergillus. A series of double mutant analyses revealed that the removal of RgsA (an RGS protein of the GanB Gα subunit), but not sfgA, flbA, rgsB, or rgsC, restored vegetative growth and conidiation in ΔAnricA. Furthermore, we found that RicA can physically interact with GanB in yeast and in vitro. Moreover, the presence of two copies or OE of pkaA suppresses the profound defects caused by ΔAnricA, indicating that RicA-mediated growth and developmental signaling is primarily through GanB and PkaA in A. nidulans. Despite the lack of conidiation, brlA and vosA mRNAs accumulated to normal levels in the ΔricA mutant. In addition, mutants overexpressing fluG or brlA (OEfluG or OEbrlA) failed to restore development in the ΔAnricA mutant. These findings suggest that the commencement of asexual development requires unknown RicA-mediated signaling input in A. nidulans.
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Affeldt KJ, Brodhagen M, Keller NP. Aspergillus oxylipin signaling and quorum sensing pathways depend on g protein-coupled receptors. Toxins (Basel) 2012; 4:695-717. [PMID: 23105976 PMCID: PMC3475224 DOI: 10.3390/toxins4090695] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 08/31/2012] [Accepted: 08/31/2012] [Indexed: 01/22/2023] Open
Abstract
Oxylipins regulate Aspergillus development and mycotoxin production and are also involved in Aspergillus quorum sensing mechanisms. Despite extensive knowledge of how these oxylipins are synthesized and what processes they regulate, nothing is known about how these signals are detected and transmitted by the fungus. G protein-coupled receptors (GPCR) have been speculated to be involved as they are known oxylipin receptors in mammals, and many putative GPCRs have been identified in the Aspergilli. Here, we present evidence that oxylipins stimulate a burst in cAMP in A. nidulans, and that loss of an A. nidulans GPCR, gprD, prevents this cAMP accumulation. A. flavus undergoes an oxylipin-mediated developmental shift when grown at different densities, and this regulates spore, sclerotial and aflatoxin production. A. flavus encodes two putative GprD homologs, GprC and GprD, and we demonstrate here that they are required to transition to a high-density development state, as well as to respond to spent medium of a high-density culture. The finding of GPCRs that regulate production of survival structures (sclerotia), inoculum (spores) and aflatoxin holds promise for future development of anti-fungal therapeutics.
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Affiliation(s)
- Katharyn J. Affeldt
- Department of Bacteriology and Department of Medical Microbiology and Immunology, 1550 Linden Drive, Madison, WI 53706, USA;
| | - Marion Brodhagen
- Department of Biology, Western Washington University, 516 High Street, Bellingham, WA 98225, USA;
| | - Nancy P. Keller
- Department of Bacteriology and Department of Medical Microbiology and Immunology, 1550 Linden Drive, Madison, WI 53706, USA;
- Author to whom correspondence should be addressed; ; Tel.: +1-608-262-9795; Fax: +1-608-262-8418
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Roze LV, Beaudry RM, Linz JE. Analysis of volatile compounds emitted by filamentous fungi using solid-phase microextraction-gas chromatography/mass spectrometry. Methods Mol Biol 2012; 944:133-42. [PMID: 23065613 DOI: 10.1007/978-1-62703-122-6_9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Here, we describe a solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) analytical approach that identifies and analyzes volatile compounds in the headspace above a live fungal culture. This approach is a sensitive, solvent-free, robust technique; most importantly from a practical standpoint, this approach is noninvasive and requires minimal sample handling. Aliquots of liquid fungal cultures are placed into vials equipped with inert septa and equilibrated at a constant temperature, and headspace gases are sampled using an SPME fiber inserted through the septum into the headspace above the fungal culture for a standardized period of time. The outer polymer coating of a fused silica fiber absorbs volatiles from the headspace; the volatiles are then desorbed in the hot GC inlet and chromatographed in the usual manner. The separated compounds are subsequently identified by mass spectrometry. All steps in volatile profiling of a single sample from volatile sorption on a fiber to obtaining a list of volatiles can take as little as 15 min or can be extended to several hours if longer sorption is required for compounds present at very low levels and/or have low rates of diffusion.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA.
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Tri6 is a global transcription regulator in the phytopathogen Fusarium graminearum. PLoS Pathog 2011; 7:e1002266. [PMID: 21980289 PMCID: PMC3182926 DOI: 10.1371/journal.ppat.1002266] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 07/28/2011] [Indexed: 11/20/2022] Open
Abstract
In F. graminearum, the transcriptional regulator Tri6 is encoded within the trichothecene gene cluster and regulates genes involved in the biosynthesis of the secondary metabolite deoxynivalenol (DON). The Tri6 protein with its Cys2His2 zinc-finger may also conform to the class of global transcription regulators. This class of global transcriptional regulators mediate various environmental cues and generally responds to the demands of cellular metabolism. To address this issue directly, we sought to find gene targets of Tri6 in F. graminearum grown in optimal nutrient conditions. Chromatin immunoprecipitation followed by Illumina sequencing (ChIP-Seq) revealed that in addition to identifying six genes within the trichothecene gene cluster, Tri1, Tri3, Tri6, Tri7, Tri12 and Tri14, the ChIP-Seq also identified 192 additional targets potentially regulated by Tri6. Functional classification revealed that, among the annotated genes, ∼40% are associated with cellular metabolism and transport and the rest of the target genes fall into the category of signal transduction and gene expression regulation. ChIP-Seq data also revealed Tri6 has the highest affinity toward its own promoter, suggesting that this gene could be subject to self-regulation. Electro mobility shift assays (EMSA) performed on the promoter of Tri6 with purified Tri6 protein identified a minimum binding motif of GTGA repeats as a consensus sequence. Finally, expression profiling of F. graminearum grown under nitrogen-limiting conditions revealed that 49 out of 198 target genes are differentially regulated by Tri6. The identification of potential new targets together with deciphering novel binding sites for Tri6, casts new light into the role of this transcriptional regulator in the overall growth and development of F. graminearum. Our knowledge of mechanisms involved in the activation and biosynthesis of DON comes largely from in vitro culture studies. Cumulated knowledge suggests that the physiological status of the fungus and the availability of nutrients are the main determining factors for DON production. Integration of various environmental cues to coordinate expression of secondary metabolic genes is thought to be mediated by a combination of global and pathway-specific transcription factors. While the global transcriptional factors respond to broad range of environmental cues such as the availability of carbon and nitrogen, the pathway-specific transcriptional factors regulate genes within a gene cluster. In F. graminearum, the transcriptional regulator Tri6 is encoded within the trichothecene gene cluster and regulates genes involved in the synthesis and transport of DON. In this report, we utilized ChIP-Seq to demonstrate that Tri6 can potentially bind to promoters and regulate genes not involved in the synthesis of DON and furthermore, many of these non-trichothecene genes are involved in various aspects of cellular metabolism, including transport and energy. Expression profiling revealed that many of the target genes are differentially regulated by Tri6, thus validating our hypothesis that Tri6 is a global regulator involved in cellular metabolism.
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Lai Y, Wang L, Qing L, Chen F. Effects of cyclic AMP on development and secondary metabolites of Monascus ruber M-7. Lett Appl Microbiol 2011; 52:420-6. [PMID: 21299575 DOI: 10.1111/j.1472-765x.2011.03022.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM To study effects of cyclic adenosine monophosphate (cAMP) on development and secondary metabolites of Monascus ruber M-7. METHODS AND RESULTS Plate culture, liquid-state fermentation (LSF) and solid-state fermentation (SSF) were used to evaluate effects of cAMP on colonial growth, spore formation and polyketide production of Strain M-7. The results revealed that the variation trends of colonial sizes, numbers of sexual spores and red pigment contents of M-7 were in a dose-dependent manner. And generally they increased and decreased with cAMP concentrations in the ranges of low cAMP concentrations and high cAMP concentrations, respectively. But the variation trends of numbers of asexual spores and citrinin production in both LSF and SSF were opposite to those of colonial sizes, sexual sporulation and red pigment. CONCLUSIONS The regulation of cAMP on development and secondary metabolites in Strain M-7 was in a dose-dependent pattern. And red pigment might convert to citrinin under changing cAMP concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY The effects of cAMP on Strain M-7 in SSF give a new clue to enhance beneficial polyketides and reduce citrinin produced by M. ruber.
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Affiliation(s)
- Y Lai
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province, China
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Roze LV, Chanda A, Laivenieks M, Beaudry RM, Artymovich KA, Koptina AV, Awad DW, Valeeva D, Jones AD, Linz JE. Volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus: veA regulates branched chain amino acid and ethanol metabolism. BMC BIOCHEMISTRY 2010; 11:33. [PMID: 20735852 PMCID: PMC2939540 DOI: 10.1186/1471-2091-11-33] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 08/24/2010] [Indexed: 01/17/2023]
Abstract
Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes. Results Volatile compounds were examined using solid phase microextraction - gas chromatography/mass spectrometry. In the wild type strain Aspergillus parasiticus SU-1, the largest group of volatiles included compounds derived from catabolism of branched chain amino acids (leucine, isoleucine, and valine); we also identified alcohols, esters, aldehydes, and lipid-derived volatiles. The number and quantity of the volatiles produced depended on media composition, time of incubation, and light-dark status. A block in aflatoxin biosynthesis or disruption of the global regulator veA affected the volatile profile. In addition to its multiple functions in secondary metabolism and development, VeA negatively regulated catabolism of branched chain amino acids and synthesis of ethanol at the transcriptional level thus playing a role in controlling carbon flow within the cell. Finally, we demonstrated that volatiles generated by a veA disruption mutant are part of the complex regulatory machinery that mediates the effects of VeA on asexual conidiation and sclerotia formation. Conclusions 1) Volatile profiling provides a rapid, effective, and powerful approach to identify changes in intracellular metabolic networks in filamentous fungi. 2) VeA coordinates the biosynthesis of secondary metabolites with catabolism of branched chain amino acids, alcohol biosynthesis, and β-oxidation of fatty acids. 3) Intracellular chemical development in A. parasiticus is linked to morphological development. 4) Understanding carbon flow through secondary metabolic pathways and catabolism of branched chain amino acids is essential for controlling and customizing production of natural products.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA.
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Palmer JM, Keller NP. Secondary metabolism in fungi: does chromosomal location matter? Curr Opin Microbiol 2010; 13:431-6. [PMID: 20627806 DOI: 10.1016/j.mib.2010.04.008] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 04/22/2010] [Accepted: 04/27/2010] [Indexed: 10/19/2022]
Abstract
Filamentous fungi produce a vast array of small molecules called secondary metabolites, which include toxins as well as antibiotics. Coregulated gene clusters are the hallmark of fungal secondary metabolism, and there is a growing body of evidence that suggests regulation is at least, in part, epigenetic. Chromatin-level control is involved in several silencing phenomena observed in fungi including mating type switching, telomere position effect (TPE), silencing of ribosomal DNA, regulation of genes involved in nutrient acquisition, and as presented here, secondary metabolite cluster expression. These phenomena are tied together by the underlying theme of chromosomal location, often near centromeres and telomeres, where facultative heterochromatin plays a role in transcription. Secondary metabolite gene clusters are often located subtelomerically and recently it has been shown that proteins involved in chromatin remodeling, such as LaeA, ClrD, CclA, and HepA mediate cluster regulation.
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Affiliation(s)
- Jonathan M Palmer
- Plant Pathology Department, University of Wisconsin, Madison, WI 53706, USA
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Roze LV, Chanda A, Linz JE. Compartmentalization and molecular traffic in secondary metabolism: a new understanding of established cellular processes. Fungal Genet Biol 2010; 48:35-48. [PMID: 20519149 DOI: 10.1016/j.fgb.2010.05.006] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 05/11/2010] [Accepted: 05/12/2010] [Indexed: 01/15/2023]
Abstract
Great progress has been made in understanding the regulation of expression of genes involved in secondary metabolism. Less is known about the mechanisms that govern the spatial distribution of the enzymes, cofactors, and substrates that mediate catalysis of secondary metabolites within the cell. Filamentous fungi in the genus Aspergillus synthesize an array of secondary metabolites and provide useful systems to analyze the mechanisms that mediate the temporal and spatial regulation of secondary metabolism in eukaryotes. For example, aflatoxin biosynthesis in Aspergillus parasiticus has been studied intensively because this mycotoxin is highly toxic, mutagenic, and carcinogenic in humans and animals. Using aflatoxin synthesis to illustrate key concepts, this review focuses on the mechanisms by which sub-cellular compartmentalization and intra-cellular molecular traffic contribute to the initiation and completion of secondary metabolism within the cell. We discuss the recent discovery of aflatoxisomes, specialized trafficking vesicles that participate in the compartmentalization of aflatoxin synthesis and export of the toxin to the cell exterior; this work provides a new and clearer understanding of how cells integrate secondary metabolism into basic cellular metabolism via the intra-cellular trafficking machinery.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI-48824, USA
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Tisch D, Schmoll M. Light regulation of metabolic pathways in fungi. Appl Microbiol Biotechnol 2009; 85:1259-77. [PMID: 19915832 PMCID: PMC2807966 DOI: 10.1007/s00253-009-2320-1] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 10/14/2009] [Accepted: 10/14/2009] [Indexed: 12/17/2022]
Abstract
Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes.
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Affiliation(s)
- Doris Tisch
- Research Area Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, Vienna University of Technology, 1060 Vienna, Austria.
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Hong SY, Linz JE. Functional expression and sub-cellular localization of the early aflatoxin pathway enzyme Nor-1 in Aspergillus parasiticus. MYCOLOGICAL RESEARCH 2009; 113:591-601. [PMID: 19217941 PMCID: PMC2765033 DOI: 10.1016/j.mycres.2009.01.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 01/14/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
Abstract
Aflatoxin biosynthesis in Aspergillus parasiticus requires at least 17 enzyme activities (from acetate). Although the activities of most aflatoxin biosynthetic enzymes have been established, the mechanisms that govern transport and sub-cellular localization of these enzymes are not clear. We developed plasmid constructs that express Nor-1 fused to a green fluorescent protein reporter (EGFP) to monitor transport and localization of this early pathway enzyme in real time in Aspergillus parasiticus. Plasmids expressing EGFP fused to Nor-1 were introduced into A. parasiticus B62 (carries non-functional Nor-1). Transformants were screened for increased aflatoxin accumulation (restored Nor-1 activity) on coconut agar medium and for EGFP expression using fluorescence microscopy. Increased aflatoxin accumulation was confirmed by TLC and ELISA. Nor-1 fused to EGFP at either the N- or C- terminus functionally complemented non-functional Nor-1 in B62 and increased aflatoxin synthesis to wild-type (N-terminus) or lower levels (C-terminus). We detected full-length Nor-1 fusion proteins in transformants with increased aflatoxin accumulation (Western blot) and determined that the expression plasmid integrated at the nor-1 locus in these cells (Southern blot). Confocal laser scanning microscopy (CLSM) demonstrated that Nor-1 fusion proteins localized in the cytoplasm and vacuoles of fungal hyphae grown on aflatoxin-inducing solid media for 48h; control EGFP (no Nor-1) did not localize to vacuoles until 72h. The highest rate of aflatoxin synthesis coincided with the highest rate of transport of Nor-1 fusion proteins to the vacuole strongly suggesting that Nor-1 is synthesized in the cytoplasm and transported to the vacuole to carry out an early step in aflatoxin synthesis.
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Affiliation(s)
- Sung-Yong Hong
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824
| | - John E. Linz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824
- National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan 48824
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
- Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824
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Georgianna DR, Payne GA. Genetic regulation of aflatoxin biosynthesis: from gene to genome. Fungal Genet Biol 2008; 46:113-25. [PMID: 19010433 DOI: 10.1016/j.fgb.2008.10.011] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 10/10/2008] [Accepted: 10/10/2008] [Indexed: 01/12/2023]
Abstract
Aflatoxins are notorious toxic secondary metabolites known for their impacts on human and animal health, and their effects on the marketability of key grain and nut crops. Understanding aflatoxin biosynthesis is the focus of a large and diverse research community. Concerted efforts by this community have led not only to a well-characterized biosynthetic pathway, but also to the discovery of novel regulatory mechanisms. Common to secondary metabolism is the clustering of biosynthetic genes and their regulation by pathway specific as well as global regulators. Recent data show that arrangement of secondary metabolite genes in clusters may allow for an important global regulation of secondary metabolism based on physical location along the chromosome. Available genomic and proteomic tools are now allowing us to examine aflatoxin biosynthesis more broadly and to put its regulation in context with fungal development and fungal ecology. This review covers our current understanding of the biosynthesis and regulation of aflatoxin and highlights new and emerging information garnered from structural and functional genomics. The focus of this review will be on studies in Aspergillus flavus and Aspergillus parasiticus, the two agronomically important species that produce aflatoxin. Also covered will be the important contributions gained by studies on production of the aflatoxin precursor sterigmatocystin in Aspergillus nidulans.
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Affiliation(s)
- D Ryan Georgianna
- Department of Plant Pathology, North Carolina State University, 851 Main Campus, Dr. Partners III Suite 267, Raleigh, NC 27606, Campus Box 7244, USA
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Schumacher J, Kokkelink L, Huesmann C, Jimenez-Teja D, Collado IG, Barakat R, Tudzynski P, Tudzynski B. The cAMP-dependent signaling pathway and its role in conidial germination, growth, and virulence of the gray mold Botrytis cinerea. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1443-1459. [PMID: 18842094 DOI: 10.1094/mpmi-21-11-1443] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In Botrytis cinerea, some components of the cAMP-dependent pathway, such as alpha subunits of heterotrimeric G proteins and the adenylate cyclase BAC, have been characterized and their impact on growth, conidiation, germination, and virulence has been demonstrated. Here, we describe the functions of more components of the cAMP cascade: the catalytic subunits BcPKA1 and BcPKA2 and the regulatory subunit BcPKAR of the cAMP-dependent protein kinase (PKA). Although Deltabcpka2 mutants showed no obvious phenotypes, growth and virulence were severely affected by deletion of both bcpka1 and bcpkaR. Similar to Deltabac, lesion development of Deltabcpka1 and DeltabcpkaR was slower than in controls and soft rot of leaves never occurred. In contrast to Deltabac, Deltabcpka1 and DeltabcpkaR mutants sporulated in planta, and growth rate, conidiation, and conidial germination were not impaired, indicating PKA-independent functions of cAMP. Unexpectedly, Deltabcpka1 and DeltabcpkaR showed identical phenotypes, suggesting the total loss of PKA activity in both mutants. The deletion of bcras2 encoding the fungal-specific Ras GTPase resulted in significantly delayed germination and decreased growth rates. Both effects could be partially restored by exogenous cAMP, suggesting that BcRAS2 activates the adenylate cyclase in addition to the Galpha subunits BCG1 and BCG3, thus influencing cAMP-dependent signal transduction.
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Affiliation(s)
- Julia Schumacher
- Institut für Botanik der Westfälischen Wilhelms-Universität Münster, Schlossgarten 3, D-48149 Münster, Germany
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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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Holmes RA, Boston RS, Payne GA. Diverse inhibitors of aflatoxin biosynthesis. Appl Microbiol Biotechnol 2008; 78:559-72. [DOI: 10.1007/s00253-008-1362-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 01/09/2008] [Accepted: 01/10/2008] [Indexed: 10/22/2022]
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Yoshinari T, Akiyama T, Nakamura K, Kondo T, Takahashi Y, Muraoka Y, Nonomura Y, Nagasawa H, Sakuda S. Dioctatin A is a strong inhibitor of aflatoxin production by Aspergillus parasiticus. MICROBIOLOGY-SGM 2007; 153:2774-2780. [PMID: 17660441 DOI: 10.1099/mic.0.2006/005629-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Dioctatin A (DotA), a metabolite of Streptomyces, is known to be an inhibitor of human dipeptidyl aminopeptidase II. Here, it was found that DotA strongly inhibited aflatoxin production by Aspergillus parasiticus, with an IC50 value of 4.0 microM. The mycelial growth of the fungus was not affected by the addition of DotA at a concentration of 50 microM, but inhibition of conidiation was observed at the same concentration. DotA inhibited production of norsolorinic acid, an early biosynthetic intermediate of aflatoxin, and it strongly reduced the mRNA levels of genes encoding aflatoxin biosynthetic enzymes, and significantly decreased the mRNA level of aflR, which encodes a key regulatory protein for aflatoxin biosynthesis. In addition to these genes, the mRNA level of brlA, which encodes a conidiation-specific transcription factor, was also reduced by the addition of DotA. It was also found that DotA dramatically enhanced kojic acid production by the fungus. Furthermore, DotA inhibited production of sterigmatocystin, which is a toxic aflatoxin biosynthetic intermediate, and it also inhibited conidiation in Aspergillus nidulans. These results indicate that DotA has pleiotropic effects on regulatory mechanisms of fungal secondary metabolite production and differentiation, leading to inhibition of aflatoxin production.
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Affiliation(s)
- Tomoya Yoshinari
- Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tetsuo Akiyama
- Microbial Chemistry Research Center, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Keita Nakamura
- Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tatsuhiko Kondo
- Department of Applied Bioscience, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoshikazu Takahashi
- Microbial Chemistry Research Center, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Yasuhiko Muraoka
- Microbial Chemistry Research Center, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Yoshiaki Nonomura
- Microbial Chemistry Research Center, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Hiromichi Nagasawa
- Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shohei Sakuda
- Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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Roze LV, Arthur AE, Hong SY, Chanda A, Linz JE. The initiation and pattern of spread of histone H4 acetylation parallel the order of transcriptional activation of genes in the aflatoxin cluster. Mol Microbiol 2007; 66:713-26. [PMID: 17919289 DOI: 10.1111/j.1365-2958.2007.05952.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 27 genes involved in aflatoxin biosynthesis are clustered within a 70 kb region in the Aspergillus parasiticus genome. Using chromatin immunoprecipitation, we demonstrated a positive correlation between the initiation and spread of histone H4 acetylation in aflatoxin promoters and the onset of accumulation of aflatoxin proteins and aflatoxin. Histone H4 acetylation in the pksA (encodes an 'early' biosynthetic pathway enzyme) promoter peaked at 30 h, prior to the increased acetylation in the omtA and ordA (encode 'late' enzymes) promoters detected at 40 h. The specific order in which pksA, ver-1 (encodes a 'middle' enzyme) and omtA transcripts accumulated in cells paralleled the pattern of spread of histone H4 acetylation. Binding of AflR, a positive regulator of aflatoxin biosynthesis, to the ordA promoter showed a positive correlation with the spread of histone H4 acetylation. The data suggest that the order of genes within the aflatoxin cluster determines the timing and order of transcriptional activation, and that the site of initiation and spread of histone H4 acetylation mediate this process. Our data indicate that the aflatoxin and adjacent sugar utilization clusters are part of a larger 'regulatory unit'.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA
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Abstract
Fungi belonging to Aspergillus section Flavi are of great economic importance in the United States due to their ability to produce toxic and carcinogenic aflatoxins in agricultural commodities. Development of control strategies against A. flavus and A. parasiticus, the major aflatoxin-producing species, is dependent upon a basic understanding of their diversity in agricultural ecosystems. This review summarizes our current knowledge of species and population diversity in the United States in relation to morphology, mycotoxin production and genetic characters. The high genetic diversity in populations of aflatoxigenic fungi is a reflection of their versatile habits in nature, which include saprotrophic colonization of plant debris in soil and parasitism of seeds and grain. Genetic variation within populations may originate from a cryptic sexual state. The advent of intensive monoculture agriculture not only increases population size but also may introduce positive selective pressure for aflatoxin production due to its link with pathogenicity in crops. Important goals in population research are to determine how section Flavi diversity in agricultural ecosystems is changing and to measure the direction of this evolution.
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Affiliation(s)
- Bruce W Horn
- US Department of Agriculture, Agricultural Research Service, National Peanut Research Laboratory, PO Box 509, Dawson, GA 39842, USA.
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Roze LV, Beaudry RM, Arthur AE, Calvo AM, Linz JE. Aspergillus volatiles regulate aflatoxin synthesis and asexual sporulation in Aspergillus parasiticus. Appl Environ Microbiol 2007; 73:7268-76. [PMID: 17890344 PMCID: PMC2168228 DOI: 10.1128/aem.00801-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspergillus parasiticus is one primary source of aflatoxin contamination in economically important crops. To prevent the potential health and economic impacts of aflatoxin contamination, our goal is to develop practical strategies to reduce aflatoxin synthesis on susceptible crops. One focus is to identify biological and environmental factors that regulate aflatoxin synthesis and to manipulate these factors to control aflatoxin biosynthesis in the field or during crop storage. In the current study, we analyzed the effects of aspergillus volatiles on growth, development, aflatoxin biosynthesis, and promoter activity in the filamentous fungus A. parasiticus. When colonies of Aspergillus nidulans and A. parasiticus were incubated in the same growth chamber, we observed a significant reduction in aflatoxin synthesis and asexual sporulation by A. parasiticus. Analysis of the headspace gases demonstrated that A. nidulans produced much larger quantities of 2-buten-1-ol (CA) and 2-ethyl-1-hexanol (EH) than A. parasiticus. In its pure form, EH inhibited growth and increased aflatoxin accumulation in A. parasiticus at all doses tested; EH also stimulated aflatoxin transcript accumulation. In contrast, CA exerted dose-dependent up-regulatory or down-regulatory effects on aflatoxin accumulation, conidiation, and aflatoxin transcript accumulation. Experiments with reporter strains carrying nor-1 promoter deletions and mutations suggested that the differential effects of CA were mediated through separate regulatory regions in the nor-1 promoter. The potential efficacy of CA as a tool for analysis of transcriptional regulation of aflatoxin biosynthesis is discussed. We also identify a novel, rapid, and reliable method to assess norsolorinic acid accumulation in solid culture using a Chroma Meter CR-300 apparatus.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA
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Shwab EK, Keller NP. Regulation of secondary metabolite production in filamentous ascomycetes. ACTA ACUST UNITED AC 2007; 112:225-30. [PMID: 18280128 DOI: 10.1016/j.mycres.2007.08.021] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 08/29/2007] [Indexed: 11/18/2022]
Abstract
Fungi are renowned for their ability to produce bioactive small molecules otherwise known as secondary metabolites. These molecules have attracted much attention due to both detrimental (e.g. toxins) and beneficial (e.g. pharmaceuticals) effects on human endeavors. Once the topic only of chemical and biochemical studies, secondary metabolism research has reached a sophisticated level in the realm of genetic regulation. This review covers the latest insights into the processes regulating secondary metabolite production in filamentous fungi.
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Affiliation(s)
- E Keats Shwab
- Plant Pathology Department, University of Wisconsin-Madison, Russell Laboratories, 1630 Linden Drive, Madison, WI 53706, USA
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