Skip to main content
PMC home page
Applied and Environmental Microbiology logoLink to Applied and Environmental Microbiology
. 1995 Aug;61(8):3019–3023. doi: 10.1128/aem.61.8.3019-3023.1995

Molecular characterization of the afl-1 locus in Aspergillus flavus.

C P Woloshuk 1, G L Yousibova 1, J A Rollins 1, D Bhatnagar 1, G A Payne 1
PMCID: PMC167577  PMID: 7487033

Abstract

An unusual mutation at the afl-1 locus, affecting aflatoxin biosynthesis in Aspergillus flavus 649, was investigated. The inability of strain 649 to produce aflatoxin was found to be the result of a large (greater than 60 kb) deletion that included a cluster of aflatoxin biosynthesis genes. Diploids formed by parasexual crosses between strain 649 and the aflatoxigenic strain 86 did not produce aflatoxin, indicating the dominant nature of the afl-1 mutation in strain 649. In metabolite feeding experiments, the diploids did not convert three intermediates in the aflatoxin pathway to aflatoxin. Northern (RNA blot) analysis of the diploids grown in medium conducive for aflatoxin production indicated that the aflatoxin pathway genes nor1, ver1, and omt1 were not expressed; however, there was low-level expression of the regulatory gene aflR. Pulsed-field electrophoresis gels indicated a larger (6 Mb) chromosome in strain 649 than the apparently homologous (4.9 Mb) chromosome in strain 86. The larger chromosome in strain 649 suggests that a rearrangement occurred in addition to the deletion. From these data, we proposed that a trans-sensing mechanism in diploids is responsible for the dominant phenotype associated with the afl-1 locus in strain 649. Such a mechanism is known in Drosophila melanogaster but has not been described for fungi.

Full Text

The Full Text of this article is available as a PDF (340.1 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Beck J., Ripka S., Siegner A., Schiltz E., Schweizer E. The multifunctional 6-methylsalicylic acid synthase gene of Penicillium patulum. Its gene structure relative to that of other polyketide synthases. Eur J Biochem. 1990 Sep 11;192(2):487–498. doi: 10.1111/j.1432-1033.1990.tb19252.x. [DOI] [PubMed] [Google Scholar]
  2. Bhatnagar D., McCormick S. P., Lee L. S., Hill R. A. Identification of O-methylsterigmatocystin as an aflatoxin B1 and G1 precursor in Aspergillus parasiticus. Appl Environ Microbiol. 1987 May;53(5):1028–1033. doi: 10.1128/aem.53.5.1028-1033.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Buchanan R. L., Jones S. B., Gerasimowicz W. V., Zaika L. L., Stahl H. G., Ocker L. A. Regulation of aflatoxin biosynthesis: assessment of the role of cellular energy status as a regulator of the induction of aflatoxin production. Appl Environ Microbiol. 1987 Jun;53(6):1224–1231. doi: 10.1128/aem.53.6.1224-1231.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Chang P. K., Cary J. W., Bhatnagar D., Cleveland T. E., Bennett J. W., Linz J. E., Woloshuk C. P., Payne G. A. Cloning of the Aspergillus parasiticus apa-2 gene associated with the regulation of aflatoxin biosynthesis. Appl Environ Microbiol. 1993 Oct;59(10):3273–3279. doi: 10.1128/aem.59.10.3273-3279.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Chang P. K., Skory C. D., Linz J. E. Cloning of a gene associated with aflatoxin B1 biosynthesis in Aspergillus parasiticus. Curr Genet. 1992 Mar;21(3):231–233. doi: 10.1007/BF00336846. [DOI] [PubMed] [Google Scholar]
  6. Chu G., Vollrath D., Davis R. W. Separation of large DNA molecules by contour-clamped homogeneous electric fields. Science. 1986 Dec 19;234(4783):1582–1585. doi: 10.1126/science.3538420. [DOI] [PubMed] [Google Scholar]
  7. Chuturgoon A. A., Dutton M. F. The affinity purification and characterization of a dehydrogenase from Aspergillus parasiticus involved in aflatoxin B1 biosynthesis. Prep Biochem. 1991;21(2-3):125–140. doi: 10.1080/10826069108018008. [DOI] [PubMed] [Google Scholar]
  8. Davis N. D., Iyer S. K., Diener U. L. Improved method of screening for aflatoxin with a coconut agar medium. Appl Environ Microbiol. 1987 Jul;53(7):1593–1595. doi: 10.1128/aem.53.7.1593-1595.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Dreesen T. D., Henikoff S., Loughney K. A pairing-sensitive element that mediates trans-inactivation is associated with the Drosophila brown gene. Genes Dev. 1991 Mar;5(3):331–340. doi: 10.1101/gad.5.3.331. [DOI] [PubMed] [Google Scholar]
  10. Frankham R. Molecular hypotheses for position-effect variegation: anti-sense transcription and promoter occlusion. J Theor Biol. 1988 Nov 8;135(1):85–107. doi: 10.1016/s0022-5193(88)80176-0. [DOI] [PubMed] [Google Scholar]
  11. Goldberg M. L., Colvin R. A., Mellin A. F. The Drosophila zeste locus is nonessential. Genetics. 1989 Sep;123(1):145–155. doi: 10.1093/genetics/123.1.145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Henikoff S. A reconsideration of the mechanism of position effect. Genetics. 1994 Sep;138(1):1–5. doi: 10.1093/genetics/138.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Henikoff S., Dreesen T. D. Trans-inactivation of the Drosophila brown gene: evidence for transcriptional repression and somatic pairing dependence. Proc Natl Acad Sci U S A. 1989 Sep;86(17):6704–6708. doi: 10.1073/pnas.86.17.6704. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hsieh D. P., Wan C. C., Billington J. A. A versiconal hemiacetal acetate converting enzyme in aflatoxin biosynthesis. Mycopathologia. 1989 Sep;107(2-3):121–126. doi: 10.1007/BF00707548. [DOI] [PubMed] [Google Scholar]
  15. Judd B. H. Transvection: allelic cross talk. Cell. 1988 Jun 17;53(6):841–843. doi: 10.1016/s0092-8674(88)90209-7. [DOI] [PubMed] [Google Scholar]
  16. Keller N. P., Dischinger H. C., Jr, Bhatnagar D., Cleveland T. E., Ullah A. H. Purification of a 40-kilodalton methyltransferase active in the aflatoxin biosynthetic pathway. Appl Environ Microbiol. 1993 Feb;59(2):479–484. doi: 10.1128/aem.59.2.479-484.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Laird C. D. Proposed genetic basis of Huntington's disease. Trends Genet. 1990 Aug;6(8):242–247. doi: 10.1016/0168-9525(90)90206-l. [DOI] [PubMed] [Google Scholar]
  18. Lin B. K., Anderson J. A. Purification and properties of versiconal cyclase from Aspergillus parasiticus. Arch Biochem Biophys. 1992 Feb 14;293(1):67–70. doi: 10.1016/0003-9861(92)90366-5. [DOI] [PubMed] [Google Scholar]
  19. Papa K. E. Genetics of Aspergillus flavus: complementation and mapping of aflatoxin mutants. Genet Res. 1979 Aug;34(1):1–9. doi: 10.1017/s0016672300019236. [DOI] [PubMed] [Google Scholar]
  20. Papa K. E. Genetics of Aspergillus flavus: linkage of aflatoxin mutants. Can J Microbiol. 1984 Jan;30(1):68–73. doi: 10.1139/m84-012. [DOI] [PubMed] [Google Scholar]
  21. Papa K. E. The parasexual cycle in Aspergillus flavus. Mycologia. 1973 Sep-Oct;65(5):1201–1205. [PubMed] [Google Scholar]
  22. Papa K. E. The parasexual cycle in Aspergillus parasiticus. Mycologia. 1978 Jul-Aug;70(4):766–773. [PubMed] [Google Scholar]
  23. Payne G. A., Nystrom G. J., Bhatnagar D., Cleveland T. E., Woloshuk C. P. Cloning of the afl-2 gene involved in aflatoxin biosynthesis from Aspergillus flavus. Appl Environ Microbiol. 1993 Jan;59(1):156–162. doi: 10.1128/aem.59.1.156-162.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Reddy T. V., Viswanathan L., Venkitasubramanian T. A. High aflatoxin production on a chemically defined medium. Appl Microbiol. 1971 Sep;22(3):393–396. doi: 10.1128/am.22.3.393-396.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Skory C. D., Chang P. K., Cary J., Linz J. E. Isolation and characterization of a gene from Aspergillus parasiticus associated with the conversion of versicolorin A to sterigmatocystin in aflatoxin biosynthesis. Appl Environ Microbiol. 1992 Nov;58(11):3527–3537. doi: 10.1128/aem.58.11.3527-3537.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Tartof K. D., Henikoff S. Trans-sensing effects from Drosophila to humans. Cell. 1991 Apr 19;65(2):201–203. doi: 10.1016/0092-8674(91)90153-p. [DOI] [PubMed] [Google Scholar]
  27. Thompson J. S., Johnson L. M., Grunstein M. Specific repression of the yeast silent mating locus HMR by an adjacent telomere. Mol Cell Biol. 1994 Jan;14(1):446–455. doi: 10.1128/mcb.14.1.446. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Trail F., Chang P. K., Cary J., Linz J. E. Structural and functional analysis of the nor-1 gene involved in the biosynthesis of aflatoxins by Aspergillus parasiticus. Appl Environ Microbiol. 1994 Nov;60(11):4078–4085. doi: 10.1128/aem.60.11.4078-4085.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Weiner B. M., Kleckner N. Chromosome pairing via multiple interstitial interactions before and during meiosis in yeast. Cell. 1994 Jul 1;77(7):977–991. doi: 10.1016/0092-8674(94)90438-3. [DOI] [PubMed] [Google Scholar]
  30. Woloshuk C. P., Foutz K. R., Brewer J. F., Bhatnagar D., Cleveland T. E., Payne G. A. Molecular characterization of aflR, a regulatory locus for aflatoxin biosynthesis. Appl Environ Microbiol. 1994 Jul;60(7):2408–2414. doi: 10.1128/aem.60.7.2408-2414.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Woloshuk C. P., Payne G. A. The alcohol dehydrogenase gene adh1 is induced in Aspergillus flavus grown on medium conducive to aflatoxin biosynthesis. Appl Environ Microbiol. 1994 Feb;60(2):670–676. doi: 10.1128/aem.60.2.670-676.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Woloshuk C. P., Seip E. R., Payne G. A., Adkins C. R. Genetic transformation system for the aflatoxin-producing fungus Aspergillus flavus. Appl Environ Microbiol. 1989 Jan;55(1):86–90. doi: 10.1128/aem.55.1.86-90.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Wu C. T., Goldberg M. L. The Drosophila zeste gene and transvection. Trends Genet. 1989 Jun;5(6):189–194. doi: 10.1016/0168-9525(89)90074-7. [DOI] [PubMed] [Google Scholar]
  34. Wu C. T., Jones R. S., Lasko P. F., Gelbart W. M. Homeosis and the interaction of zeste and white in Drosophila. Mol Gen Genet. 1989 Sep;218(3):559–564. doi: 10.1007/BF00332424. [DOI] [PubMed] [Google Scholar]
  35. Yu J., Cary J. W., Bhatnagar D., Cleveland T. E., Keller N. P., Chu F. S. Cloning and characterization of a cDNA from Aspergillus parasiticus encoding an O-methyltransferase involved in aflatoxin biosynthesis. Appl Environ Microbiol. 1993 Nov;59(11):3564–3571. doi: 10.1128/aem.59.11.3564-3571.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Yu J., Chang P. K., Cary J. W., Wright M., Bhatnagar D., Cleveland T. E., Payne G. A., Linz J. E. Comparative mapping of aflatoxin pathway gene clusters in Aspergillus parasiticus and Aspergillus flavus. Appl Environ Microbiol. 1995 Jun;61(6):2365–2371. doi: 10.1128/aem.61.6.2365-2371.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Applied and Environmental Microbiology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES