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Regulation of aflatoxin synthesis by FadA/cAMP/protein kinase A signaling in Aspergillus parasiticus

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Abstract

Analysis of fadA and pkaA mutants in the filamentous fungus Aspergillus nidulans demonstrated that FadA (Gα) stimulates cyclic AMP (cAMP)-dependent protein kinase A (PKA)activity resulting, at least in part, in inhibition of conidiation and sterigmatocystin (ST) biosynthesis [33]. In contrast, cAMP added to the growth medium stimulates aflatoxin (AF) synthesis in Aspergillus parasiticus [34]. Our goal was to explain these conflicting reports and to provide mechanistic detail on the role of FadA, cAMP, and PKA in regulation of AF synthesis and conidiation in A. parasiticus. cAMP or dibutyryl-cAMP (DcAMP) were added to a solid growth medium and intracellular cyclic nucleotide levels, PKA activity, and nor-1 promoter activity were measured in A. parasiticus D8D3 (nor-1::GUS reporter) and TJYP1-22(fadAGA2R, activated allele). Similar to Tice and Buchanan [34], cAMP or DcAMP stimulated AF synthesis (and conidiation) associated with an AflR-dependent increase in nor-1 promoter activity. However, treatment resulted in a 100-fold increase in intracellular cAMP/DcAMP accompanied by a 40 to 80 fold decrease in total PKA activity. The fadAG42R allele in TJYP1-22 decreased AF synthesis and conidiation, increased basal PKA activity 10fold, and decreased total PKA activity 2 fold. In TJYP1-22, intracellular cAMP increased 2 fold without cAMP or DcAMP treatment; treatment did not stimulate conidiation or AF synthesis. Based on these data, we conclude that: (1) FadA/ PKA regulate toxin synthesis and conidiation via similar mechanisms in Aspergillus spp.; and (2) intracellular cAMP levels, at least in part, mediate a PKA-dependent regulatory influence on conidiation and AF synthesis.

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References

  1. Adams TH., Wiesler JK, Yu JH. Asexual sporulation in Asper-gillus nidulans. Microbiol Mol Biol Rev 1998; 62: 35–54.

    Google Scholar 

  2. Bennett JW, Papa KE. Genetics in aflatoxigenic Aspergillus species. Adv Plant Pathol 1987; 6: 263–280.

    Google Scholar 

  3. Buchanan RL, Lewis DF. Regulation of aflatoxin biosynthesis: Effect of glucose on activities of various glycolytic enzymes. Appl Environ Microbiol 1984; 48: 306–310.

    Google Scholar 

  4. Cary JW, Ehrlich KC, Wright M, Chang PK, Bhatnagar D. Generation of aflR disruption mutants of Aspergillus parasiticus. Appl Microbiol Biotechnol 2000; 53: 680–684.

    Google Scholar 

  5. Chang PK, Cary JW, Yu J, Bhatnagar D, Cleveland TE. The Aspergillus parasiticus polyketide synthase gene pksA,a homolog of Aspergillus nidulans wA, is required for aflatoxin B1 biosynthesis. Mol Gen Genet 1995; 248: 270–277.

    Google Scholar 

  6. Chang PK, Skory CD, Linz JE. Cloning of a gene associated with aflatoxin B1 biosynthesis in Aspergillus parasiticus.Curr Genet 1992: 21: 231–233.

    Google Scholar 

  7. Chiou CS, Miller M, Wilson DL, Trail F, Linz JE. Chromo-somal location plays a role in regulation of aflatoxin gene expression in Aspergillus parasiticus. Appl Environ Microbiol 2002; 68(1): 306–315.

    Google Scholar 

  8. Choi W, Dean RA. The adenylate cyclase gene MAC1 of Mag-naporthe grisea controls appressorium formation and other aspects of growth and development. Plant Cell 1997; 9: 1973–1983.

    Google Scholar 

  9. Ehrlich KC, Montalbano BG, Bhatnagar D, Cleveland TE. Al-teration of different domains in AflR affects aflatoxin pathway metabolism in Aspergillus parasiticus transformants. Fungal Genet Biol 1998; 23: 279–287.

    Google Scholar 

  10. Ehrlich KC, Montalbano BG, Cary JW. Binding of the C6-zinc cluster protein, AFLR, to the promoters of aflatoxin pathway biosynthesis genes in Aspergillus parasiticus. Gene 1999; 230: 249–257

    Google Scholar 

  11. Fillinger S, Chaveroche MK, Shimizu K, Keller N, d'Enfert C. cAMP and ras signaling independently control spore germina-tion in the filamentous fungus Aspergillus nidulans. Molecular Microbiology 2002; 44: 1001–1016.

    Google Scholar 

  12. Gimeno CJ, Ljungdahl PO, Styles CA, Fink GR. Unipolar cell divisions in the yeast S. cerevisiae lead to filamentous growth: Regulation by starvation and Ras. Cell 1992; 68: 1077–1090.

    Google Scholar 

  13. Gold S, Duncan G, Barrett K, Kronstad J. cAMP regulates morphogenesis in the fungal pathogen Ustilago maydis. Genes and Develop 1994; 8: 2805–2816.

    Google Scholar 

  14. Guzman-de-Pena D, Ruiz-Herrera J. Relationship between aflatoxin biosynthesis and conidiation in Aspergillus parasiticus. Fungal Genet Biol 1997; 21: 198–205.

    Google Scholar 

  15. Hamer JE, Talbot NJ. Infection-related development in the rice blast fungus Magnaporthe grisea. Curr Opin Microbiol 1998; 1: 693–697.

    Google Scholar 

  16. Hicks J, Yu JH, Keller NP, Adams TH. Aspergillus sporulation and mycotoxin production both require inactivation of the FadA Gα protein-dependent signaling pathway. EMBO J 1997; 16: 4916–4923.

    Google Scholar 

  17. Ikeda K, Okazaki R, Inoue D, Ogata E, Matsumoto T. Tran-scription of the gene for parathyroid hormone-related peptide from the humans activated through a cAMP-dependent path-way by prostaglandin E1 in HTLV-I-infected T cell. J Biol Chem 1993; 268(2): 1174–11719.

    Google Scholar 

  18. Ivey FD, Yang Q, Borkovich KA. Positive regulation of ad-enylyl cyclase activity by Gα i homolog in Neurospora crassa. Fungal Genet Biol 1999; 26: 48–61.

    Google Scholar 

  19. Kale SP, Bhatnagar D, Bennett JW. Isolation and characterization of morphological variants of Aspergillus parasiticus deficient in secondary metabolite production. Mycol Res 1994; 98: 645–652.

    Google Scholar 

  20. Kawasaki H, Springett GM, Mochizuki N, Toki S, Hakaya M, Matsuda M, Housman DE, Graybiel AM. A family of cAMP-binding proteins that directly activate Rap1. Science 1998; 2820(5397): 2274–2279.

    Google Scholar 

  21. Liang SH. The function and expression of the ver-1 gene and localization of the Ver-1 protein involved in aflatoxin biosyn-thesis in Aspergillus parasiticus [Dissertation]. East Lansing, Michigan: Michigan State University, 1996.

    Google Scholar 

  22. Liang SH, Wu TS, Lee R, Chu FS, Linz JE. Analysis of mechanisms regulating expression of the ver-1 gene, involved in aflatoxin biosynthesis. Appl Environ Microbiol 1997; 63: 1058–1065.

    Google Scholar 

  23. Mahanti N, Bhatnagar D, Cary JW, Joubran J, Linz JE. Struc-ture and function of fas-1A, a gene encoding a putative fatty acid synthetase directly involved in aflatoxin biosynthesis in Aspergillus parasiticus. Appl Environ Microbiol 1996; 62: 191–195.

    Google Scholar 

  24. Orlowski M. Mucor dimorphism. Microbiol Rev 1991; 55: 234–258.

    Google Scholar 

  25. Payne GA, Brown MP. Genetics and physiology of aflatoxin biosynthesis. Annu Rev Phytopathol 1998; 36: 329–362.

    Google Scholar 

  26. Payne GA, Hugler WM. Effect of specific amino acids on growth and aflatoxin production by Aspergillus parasiticus and Aspergillus flavus in defined media. Appl Environ Microbiol 1983; 46: 805–812.

    Google Scholar 

  27. Pestka JJ. Enhanced surveillance of food-borne mycotoxins by immunochemical assay. J Assoc Off Anal Chem 1988; 71: 1075–1081.

    Google Scholar 

  28. Reib J. Development of Aspergillus parasiticus and formation of aflatoxin B1 under the influence of conidiogenesis affecting compounds. Arch Microbiol 1982; 133: 236–238.

    Google Scholar 

  29. Rollins JA, Dickman MB. Increase in endogenous and exo-genous cyclic AMP levels inhibits sclerotial development in Sclerotinia sclerotiorum. Appl Environ Microbiol 1998; 64: 2539–2544.

    Google Scholar 

  30. Roze LV, Linz JE. Lovastatin triggers an apoptosis-like cell death process in the fungus Mucor racemosus. Fungal Genet Biol 1998; 25: 119–133.

    Google Scholar 

  31. Roze LV, Mahanti N, Mehigh R, McConnell DG, Linz JE. Evidence that MRas1 andMRas3 are associated with dis-tinct functions during growth and morphogenesis in the fungus Mucor racemosus. Fungal Genet Biol 1999; 28: 171–189.

    Google Scholar 

  32. Sabie FT, Gadd GM. Effect of nucleosides and nucleotides and the relationship between cellular adenosine 3:5-cyclic mono-phosphate (cyclic AMP) and germ tube formation in Candida albicans. Mycopathology 1992; 19: 147–156.

    Google Scholar 

  33. Shimizu K, Keller N. Genetic involvement of a cAMP-dependent protein kinase in a G protein signaling pathway reg-ulating morphological and chemical transitions in Aspergillus nidulans. Genetics 2001; 157: 591–600.

    Google Scholar 

  34. Tice G, Buchanan RL. Regulation of aflatoxin biosynthesis: Effect of exogenously supplied cyclic nucleotides. J Food Sci 1981; 47: 153–157.

    Google Scholar 

  35. Trail F, Chang PK, Cary J, Linz JE. Structural and functional analysis of the nor-1 gene involved it the biosynthesis of aflatoxin by Aspergillus parasiticus. Appl Environ Microbiol 1994; 60: 4078–4085.

    Google Scholar 

  36. Trail F, Mahanti N, Linz, JE. Molecular biology of aflatoxin biosynthesis. Microbiol 1995; 141: 755–765.

    Google Scholar 

  37. Wilson DL, Wu TS, Trail F, Linz JE. The expression of â-glucuronidase reporter constructs of aflatoxin biosynthesis genes is position dependent. Aflatoxin Elimination Workshop 1996; 331–332.

  38. Woloshuk CP, Prieto R. Genetic organization and function of the aflatoxin B1 biosynthetic genes. FEMS Microbiol Lett 1998; 160: 169–176.

    Google Scholar 

  39. Yang Q, Borkovich KA. Mutational activation of a Gαi causes uncontrolled proliferation of aerial hyphae and increased sensitivity to heat and oxidative stress in Neurospora crassa. Genetics 1999; 151: 107–117.

    Google Scholar 

  40. Zhou R. The function, expression and localization of the nor-1 protein involved in aflatoxin B1 biosynthesis; the function of fluP, a gene associated with sporulation in Aspergillus parasiticus [Dissertation] East Lansing, MI: Michigan State University, 1997.

    Google Scholar 

  41. Zhou R, Linz JE. Enzymatic functions of the nor-1 protein in aflatoxin biosynthesis in Aspergillus parasiticus. Appl Environ Microbiol 1999; 65: 5639–5641.

    Google Scholar 

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Authors and Affiliations

  1. Department of Food Science and Human Nutrition, Michigan State University (MSU), USA

    Ludmila V. Roze & John E. Linz

  2. Department of Horticulture, MSU, USA

    Randolph M. Beaudry

  3. Department of Plant Pathology, University of Wisconsin-Madison, USA

    Nancy P. Keller

  4. Department of Microbiology and Molecular Genetics, MSU, USA

    John E. Linz

  5. National Food Safety and Toxicology Center, MSU, USA

    John E. Linz

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  1. Ludmila V. Roze
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  2. Randolph M. Beaudry
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  3. Nancy P. Keller
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  4. John E. Linz
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Roze, L.V., Beaudry, R.M., Keller, N.P. et al. Regulation of aflatoxin synthesis by FadA/cAMP/protein kinase A signaling in Aspergillus parasiticus . Mycopathologia 158, 219–232 (2004). https://doi.org/10.1023/B:MYCO.0000041841.71648.6e

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