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J Bacteriol. 1995 August; 177(16): 4792–4800.
PMCID: PMC177246

Sterigmatocystin biosynthesis in Aspergillus nidulans requires a novel type I polyketide synthase.


A filamentous fungus, Aspergillus nidulans, produces the carcinogenic mycotoxin sterigmatocystin (ST), which is a polyketide-derived secondary metabolite. A gene (pksST) encoding the ST polyketide synthase (PKSst) in A. nidulans was cloned, sequenced, and characterized. Large induced deletion mutants, which did not make ST or any ST intermediates, were used to identify genes associated with ST biosynthesis. Among the transcripts detected within the deletion region, which showed developmental expression with ST production, was a 7.2-kb transcript. Functional inactivation of the gene encoding the 7.2-kb transcript blocked production of ST and all ST intermediate substrates but did not affect transcription of the pathway genes, indicating that this gene was involved in a very early step of ST biosynthesis. These results also indicate that PKSst was not associated with activation of other ST genes. Sequencing of the region spanning this gene revealed that it encoded a polypeptide with a deduced length of 2,181 amino acids that had high levels of similarity to many of the known polyketide synthases and FASs. This gene, pksST, encodes a multifunctional novel type I polyketide synthase which has as active sites a beta-ketoacyl acyl carrier protein synthase, an acyltransferase, duplicated acyl carrier proteins, and a thioesterase, all of these catalytic sites may be multiply used. In addition, a 1.9-kb transcript, which also showed developmental expression, was mapped adjacent to pksST, and the sequence of this gene revealed that it encoded a cytochrome P-450 monooxygenase-like peptide.

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Selected References

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  • Adamson RH. Induction of hepatocellular carcinoma in nonhuman primates by chemical carcinogens. Cancer Detect Prev. 1989;14(2):215–219. [PubMed]
  • Aguilar F, Hussain SP, Cerutti P. Aflatoxin B1 induces the transversion of G-->T in codon 249 of the p53 tumor suppressor gene in human hepatocytes. Proc Natl Acad Sci U S A. 1993 Sep 15;90(18):8586–8590. [PubMed]
  • Amy CM, Witkowski A, Naggert J, Williams B, Randhawa Z, Smith S. Molecular cloning and sequencing of cDNAs encoding the entire rat fatty acid synthase. Proc Natl Acad Sci U S A. 1989 May;86(9):3114–3118. [PubMed]
  • MacCabe AP, van Liempt H, Palissa H, Unkles SE, Riach MB, Pfeifer E, von Döhren H, Kinghorn JR. Delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase from Aspergillus nidulans. Molecular characterization of the acvA gene encoding the first enzyme of the penicillin biosynthetic pathway. J Biol Chem. 1991 Jul 5;266(19):12646–12654. [PubMed]
  • Aramayo R, Adams TH, Timberlake WE. A large cluster of highly expressed genes is dispensable for growth and development in Aspergillus nidulans. Genetics. 1989 May;122(1):65–71. [PubMed]
  • Baertschi SW, Raney KD, Shimada T, Harris TM, Guengerich FP. Comparison of rates of enzymatic oxidation of aflatoxin B1, aflatoxin G1, and sterigmatocystin and activities of the epoxides in forming guanyl-N7 adducts and inducing different genetic responses. Chem Res Toxicol. 1989 Mar-Apr;2(2):114–112. [PubMed]
  • 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. [PubMed]
  • Bennett JW, Christensen SB. New perspectives on aflatoxin biosynthesis. Adv Appl Microbiol. 1983;29:53–92. [PubMed]
  • Bhatnagar D, Ullah AH, Cleveland TE. Purification and characterization of a methyltransferase from Aspergillus parasiticus SRRC 163 involved in aflatoxin biosynthetic pathway. Prep Biochem. 1988;18(3):321–349. [PubMed]
  • Brody H, Griffith J, Cuticchia AJ, Arnold J, Timberlake WE. Chromosome-specific recombinant DNA libraries from the fungus Aspergillus nidulans. Nucleic Acids Res. 1991 Jun 11;19(11):3105–3109. [PMC free article] [PubMed]
  • Brown DW, Salvo JJ. Isolation and Characterization of Sexual Spore Pigments from Aspergillus nidulans. Appl Environ Microbiol. 1994 Mar;60(3):979–983. [PMC free article] [PubMed]
  • Chang PK, Cary JW, Bhatnagar D, Cleveland TE, Bennett JW, Linz JE, Woloshuk CP, Payne GA. Cloning of the Aspergillus parasiticus apa-2 gene associated with the regulation of aflatoxin biosynthesis. Appl Environ Microbiol. 1993 Oct;59(10):3273–3279. [PMC free article] [PubMed]
  • Church GM, Gilbert W. Genomic sequencing. Proc Natl Acad Sci U S A. 1984 Apr;81(7):1991–1995. [PubMed]
  • Cortes J, Haydock SF, Roberts GA, Bevitt DJ, Leadlay PF. An unusually large multifunctional polypeptide in the erythromycin-producing polyketide synthase of Saccharopolyspora erythraea. Nature. 1990 Nov 8;348(6297):176–178. [PubMed]
  • Davis NK, Chater KF. Spore colour in Streptomyces coelicolor A3(2) involves the developmentally regulated synthesis of a compound biosynthetically related to polyketide antibiotics. Mol Microbiol. 1990 Oct;4(10):1679–1691. [PubMed]
  • Devereux J, Haeberli P, Smithies O. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 1984 Jan 11;12(1 Pt 1):387–395. [PMC free article] [PubMed]
  • Donadio S, Staver MJ, McAlpine JB, Swanson SJ, Katz L. Modular organization of genes required for complex polyketide biosynthesis. Science. 1991 May 3;252(5006):675–679. [PubMed]
  • Donkersloot JA, Mateles RI, Yang SS. Isolation of averufin from a mutant of Aspergillus parasiticus impaired in aflatoxin biosynthesis. Biochem Biophys Res Commun. 1972 Jun 9;47(5):1051–1055. [PubMed]
  • Dutton MF. Enzymes and aflatoxin biosynthesis. Microbiol Rev. 1988 Jun;52(2):274–295. [PMC free article] [PubMed]
  • Fujii K, Kurata H, Odashima S, Hatsuda Y. Tumor induction by a single subcutaneous injection of sterigmatocystin in newborn mice. Cancer Res. 1976 May;36(5):1615–1618. [PubMed]
  • Gibson TJ, Coulson AR, Sulston JE, Little PF. Lorist2, a cosmid with transcriptional terminators insulating vector genes from interference by promoters within the insert: effect on DNA yield and cloned insert frequency. Gene. 1987;53(2-3):275–281. [PubMed]
  • Gutiérrez S, Díez B, Montenegro E, Martín JF. Characterization of the Cephalosporium acremonium pcbAB gene encoding alpha-aminoadipyl-cysteinyl-valine synthetase, a large multidomain peptide synthetase: linkage to the pcbC gene as a cluster of early cephalosporin biosynthetic genes and evidence of multiple functional domains. J Bacteriol. 1991 Apr;173(7):2354–2365. [PMC free article] [PubMed]
  • Harker CL, Ellis TH, Coen ES. Identification and genetic regulation of the chalcone synthase multigene family in pea. Plant Cell. 1990 Mar;2(3):185–194. [PubMed]
  • Hitokoto H, Morozumi S, Wauke T, Sakai S, Yoshikawa S. Chemically defined medium for high yields of sterigmatocystin. Mycopathologia. 1982 May 22;78(2):99–105. [PubMed]
  • Hohn TM, McCormick SP, Desjardins AE. Evidence for a gene cluster involving trichothecene-pathway biosynthetic genes in Fusarium sporotrichioides. Curr Genet. 1993 Oct;24(4):291–295. [PubMed]
  • Holzer KP, Liu W, Hammes GG. Molecular cloning and sequencing of chicken liver fatty acid synthase cDNA. Proc Natl Acad Sci U S A. 1989 Jun;86(12):4387–4391. [PubMed]
  • Hopwood DA, Sherman DH. Molecular genetics of polyketides and its comparison to fatty acid biosynthesis. Annu Rev Genet. 1990;24:37–66. [PubMed]
  • Jelinek CF, Pohland AE, Wood GE. Worldwide occurrence of mycotoxins in foods and feeds--an update. J Assoc Off Anal Chem. 1989 Mar-Apr;72(2):223–230. [PubMed]
  • Katz L, Donadio S. Polyketide synthesis: prospects for hybrid antibiotics. Annu Rev Microbiol. 1993;47:875–912. [PubMed]
  • Keller NP, Dischinger HC, Jr, Bhatnagar D, Cleveland TE, Ullah AH. Purification of a 40-kilodalton methyltransferase active in the aflatoxin biosynthetic pathway. Appl Environ Microbiol. 1993 Feb;59(2):479–484. [PMC free article] [PubMed]
  • Keller NP, Kantz NJ, Adams TH. Aspergillus nidulans verA is required for production of the mycotoxin sterigmatocystin. Appl Environ Microbiol. 1994 May;60(5):1444–1450. [PMC free article] [PubMed]
  • Kimura N, Tsuge T. Gene cluster involved in melanin biosynthesis of the filamentous fungus Alternaria alternata. J Bacteriol. 1993 Jul;175(14):4427–4435. [PMC free article] [PubMed]
  • Maloney AP, VanEtten HD. A gene from the fungal plant pathogen Nectria haematococca that encodes the phytoalexin-detoxifying enzyme pisatin demethylase defines a new cytochrome P450 family. Mol Gen Genet. 1994 Jun 3;243(5):506–514. [PubMed]
  • Marsden AF, Caffrey P, Aparicio JF, Loughran MS, Staunton J, Leadlay PF. Stereospecific acyl transfers on the erythromycin-producing polyketide synthase. Science. 1994 Jan 21;263(5145):378–380. [PubMed]
  • Mathur M, Kolattukudy PE. Molecular cloning and sequencing of the gene for mycocerosic acid synthase, a novel fatty acid elongating multifunctional enzyme, from Mycobacterium tuberculosis var. bovis Bacillus Calmette-Guerin. J Biol Chem. 1992 Sep 25;267(27):19388–19395. [PubMed]
  • Matsushima K, Ando Y, Hamasaki T, Yabe K. Purification and characterization of two versiconal hemiacetal acetate reductases involved in aflatoxin biosynthesis. Appl Environ Microbiol. 1994 Jul;60(7):2561–2567. [PMC free article] [PubMed]
  • Mayorga ME, Timberlake WE. The developmentally regulated Aspergillus nidulans wA gene encodes a polypeptide homologous to polyketide and fatty acid synthases. Mol Gen Genet. 1992 Nov;235(2-3):205–212. [PubMed]
  • McDaniel R, Ebert-Khosla S, Hopwood DA, Khosla C. Engineered biosynthesis of novel polyketides. Science. 1993 Dec 3;262(5139):1546–1550. [PubMed]
  • Miller BL, Miller KY, Timberlake WE. Direct and indirect gene replacements in Aspergillus nidulans. Mol Cell Biol. 1985 Jul;5(7):1714–1721. [PMC free article] [PubMed]
  • Muench KF, Misra RP, Humayun MZ. Sequence specificity in aflatoxin B1--DNA interactions. Proc Natl Acad Sci U S A. 1983 Jan;80(1):6–10. [PubMed]
  • Northolt MD, van Egmond HP, Soentoro P, Deijll E. Fungal growth and the presence of sterigmatocystin in hard cheese. J Assoc Off Anal Chem. 1980 Jan;63(1):115–119. [PubMed]
  • O'Hara EB, Timberlake WE. Molecular characterization of the Aspergillus nidulans yA locus. Genetics. 1989 Feb;121(2):249–254. [PubMed]
  • Ong TM, De Serres FJ. Mutagenicity of chemical carcinogens in Neurospora crassa. Cancer Res. 1972 Sep;32(9):1890–1893. [PubMed]
  • Ong TM, Serres FJ. Mutation induction by difunctional alkylating agents in Neurospora crassa. Genetics. 1975 Jul;(3):475–482. [PubMed]
  • Payne GA, Nystrom GJ, Bhatnagar D, Cleveland TE, Woloshuk CP. Cloning of the afl-2 gene involved in aflatoxin biosynthesis from Aspergillus flavus. Appl Environ Microbiol. 1993 Jan;59(1):156–162. [PMC free article] [PubMed]
  • Sanger F, Nicklen S, Coulson AR. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. [PubMed]
  • Scotti C, Piatti M, Cuzzoni A, Perani P, Tognoni A, Grandi G, Galizzi A, Albertini AM. A Bacillus subtilis large ORF coding for a polypeptide highly similar to polyketide synthases. Gene. 1993 Aug 16;130(1):65–71. [PubMed]
  • Shen B, Hutchinson CR. Enzymatic synthesis of a bacterial polyketide from acetyl and malonyl coenzyme A. Science. 1993 Dec 3;262(5139):1535–1540. [PubMed]
  • Shimada T, Guengerich FP. Evidence for cytochrome P-450NF, the nifedipine oxidase, being the principal enzyme involved in the bioactivation of aflatoxins in human liver. Proc Natl Acad Sci U S A. 1989 Jan;86(2):462–465. [PubMed]
  • Skory CD, Chang PK, Cary J, Linz JE. 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. [PMC free article] [PubMed]
  • Skory CD, Chang PK, Linz JE. Regulated expression of the nor-1 and ver-1 genes associated with aflatoxin biosynthesis. Appl Environ Microbiol. 1993 May;59(5):1642–1646. [PMC free article] [PubMed]
  • Smith DJ, Burnham MK, Bull JH, Hodgson JE, Ward JM, Browne P, Brown J, Barton B, Earl AJ, Turner G. Beta-lactam antibiotic biosynthetic genes have been conserved in clusters in prokaryotes and eukaryotes. EMBO J. 1990 Mar;9(3):741–747. [PubMed]
  • Stack M, Rodricks JV. Method for analysis and chemical confirmation of sterigmatocystin. J Assoc Off Anal Chem. 1971 Jan;54(1):86–90. [PubMed]
  • Summers RG, Wendt-Pienkowski E, Motamedi H, Hutchinson CR. Nucleotide sequence of the tcmII-tcmIV region of the tetracenomycin C biosynthetic gene cluster of Streptomyces glaucescens and evidence that the tcmN gene encodes a multifunctional cyclase-dehydratase-O-methyl transferase. J Bacteriol. 1992 Mar;174(6):1810–1820. [PMC free article] [PubMed]
  • Tai MH, Chirala SS, Wakil SJ. Roles of Ser101, Asp236, and His237 in catalysis of thioesterase II and of the C-terminal region of the enzyme in its interaction with fatty acid synthase. Proc Natl Acad Sci U S A. 1993 Mar 1;90(5):1852–1856. [PubMed]
  • Tang CM, Cohen J, Holden DW. An Aspergillus fumigatus alkaline protease mutant constructed by gene disruption is deficient in extracellular elastase activity. Mol Microbiol. 1992 Jun;6(12):1663–1671. [PubMed]
  • Timberlake WE. Molecular genetics of Aspergillus development. Annu Rev Genet. 1990;24:5–36. [PubMed]
  • Yabe K, Hamasaki T. Stereochemistry during aflatoxin biosynthesis: cyclase reaction in the conversion of versiconal to versicolorin B and racemization of versiconal hemiacetal acetate. Appl Environ Microbiol. 1993 Aug;59(8):2493–2500. [PMC free article] [PubMed]
  • Yager LN, Kurtz MB, Champe SP. Temperature-shift analysis of conidial development in Aspergillus nidulans. Dev Biol. 1982 Sep;93(1):92–103. [PubMed]
  • Yu J, Cary JW, Bhatnagar D, Cleveland TE, Keller NP, Chu FS. 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. [PMC free article] [PubMed]

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