Clustered Pathway Genes in Aflatoxin Biosynthesis

Yu, Jiujiang; Chang, Perng‐Kuang; Ehrlich, Kenneth C.; Cary, Jeffrey W.; Bhatnagar, Deepak; Cleveland, Thomas E.; Payne, Gary A.; Linz, John E.; Woloshuk, Charles P.; Bennett, Joan W.

doi:10.1128/aem.70.3.1253-1262.2004

Cited by 725 publications

(637 citation statements)

References 119 publications

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“…Fungal genes encoding enzymes involved in the production of secondary metabolites are usually contained in clusters on chromosomes. The existence of a gene cluster related to mycotoxin synthesis has been demonstrated for aflatoxins, fumonisins, trichothecenes and ergot alkaloids (Yu et al, 2004;Seo et al, 2001;Proctor et al, 2003;Kimura et al, 2007;Panaccione, 2005). By contrast, a gene cluster related to patulin biosynthesis has not been described.…”

Section: Introductionmentioning

confidence: 99%

Molecular cloning and functional characterization of two CYP619 cytochrome P450s involved in biosynthesis of patulin in Aspergillus clavatus

Artigot¹,

Loiseau²,

Laffitte³

et al. 2009

Microbiology

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Patulin is an acetate-derived tetraketide mycotoxin produced by several fungal species, especially Aspergillus, Penicillium and Byssochlamys species. The health risks due to patulin consumption by humans have led many countries to regulate it in human food. Previous studies have shown the involvement of cytochrome P450 monooxygenases in the hydroxylation of two precursors of patulin, m-cresol and m-hydroxybenzylalcohol. In the present study, two cytochrome P450 genes were identified in the genome sequence of Aspergillus clavatus, a patulin-producing species. Both mRNAs were strongly co-expressed during patulin production. CYP619C2, encoded by the first gene, consists of 529 aa, while the second cytochrome, CYP619C3, consists of 524 aa. The coding sequences were used to perform the heterologous expression of functional enzymes in Saccharomyces cerevisiae. The bioconversion assays showed that CYP619C3 catalysed the hydroxylation of m-cresol to yield m-hydroxybenzyl alcohol. CYP619C2 catalysed the hydroxylation of m-hydroxybenzyl alcohol and m-cresol to gentisyl alcohol and 2,5-dihydroxytoluene (toluquinol), respectively. Except for the last compound, all enzyme products are known precursors of patulin. Taken together, these data strongly suggest the involvement of CYP619C2 and CYP619C3 in the biosynthesis of patulin. CYP619C2 and CYP619C3 are located near to two other genes involved in patulin biosynthesis, namely the 6-methylsalicylic acid synthase (6msas) and isoepoxydon dehydrogenase (idh) genes. The current data associated with an analysis of the sequence of A. clavatus suggest the presence of a cluster of 15 genes involved in patulin biosynthesis.

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Section: Introductionmentioning

confidence: 99%

Molecular cloning and functional characterization of two CYP619 cytochrome P450s involved in biosynthesis of patulin in Aspergillus clavatus

Artigot¹,

Loiseau²,

Laffitte³

et al. 2009

Microbiology

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“…In A. flavus, the clustered pathway genes have been detailed, and in some cases new gene names have recently been given [3,4]. Some of the key genes in the aflatoxin biosynthesis include aflF (old name; norB), aflD (¼nor-1) and aflE (norA), which encode a dehydrogenase and two reductases which convert norsolorinic acid to averantin; aflM (¼ver-1) is a dehydrogenase which converts versicolorin A to demethylsterigmatocystin; aflaO (¼omtB) is a O-methyltransferase I or O-methyltransferase B, which is involved in the conversion of demethylsterigmatocystin to sterigmatocystin and dihydro-demethylsterigmostocystin to dihydrosterigmatocystin; aflP (¼omtA) is an O-methyltransferase A or II which converts sterigmatocystin to O-methylsterigmatocystin as well as demethylsterigmatocystin to dihydro-O-methylsterigmatocystin; other genes such as aflQ (¼ordA) and aflX (¼ordB) have been shown to be involved in the final part of the biosynthetic pathway, as oxidoreductase-P450 monooxygenase and monoxygenase oxidase.…”

Section: Introductionmentioning

confidence: 99%

“…Economically and biologically the most important fungal species able to produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus [1]. The aflatoxin biosynthesis gene cluster of A. parasiticus has been completely elucidated [2][3][4]. Indeed, a whole-genome microarray of A. flavus has been used to study the regulation of aflatoxin biosynthesis genes [5].…”

Section: Introductionmentioning

confidence: 99%

A systems approach to model the relationship between aflatoxin gene cluster expression, environmental factors, growth and toxin production by Aspergillus flavus

Abdel-Hadi

Schmidt‐Heydt

Parra‐Saldívar

et al. 2011

J. R. Soc. Interface.

142

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A microarray analysis was used to examine the effect of combinations of water activity (a w , 0.995-0.90) and temperature (20 -428C) on the activation of aflatoxin biosynthetic genes (30 genes) in Aspergillus flavus grown on a conducive YES (20 g yeast extract, 150 g sucrose, 1 g MgSO 4 . 7H 2 O) medium. The relative expression of 10 key genes (aflF, aflD, aflE, aflM, aflO, aflP, aflQ, aflX, aflR and aflS) in the biosynthetic pathway was examined in relation to different environmental factors and phenotypic aflatoxin B 1 (AFB 1 ) production. These data, plus data on relative growth rates and AFB 1 production under different a w Â temperature conditions were used to develop a mixed-growth-associated product formation model. The gene expression data were normalized and then used as a linear combination of the data for all 10 genes and combined with the physical model. This was used to relate gene expression to a w and temperature conditions to predict AFB 1 production. The relationship between the observed AFB 1 production provided a good linear regression fit to the predicted production based in the model. The model was then validated by examining datasets outside the model fitting conditions used (378C, 408C and different a w levels). The relationship between structural genes (aflD, aflM) in the biosynthetic pathway and the regulatory genes (aflS, aflJ) was examined in relation to a w and temperature by developing ternary diagrams of relative expression. These findings are important in developing a more integrated systems approach by combining gene expression, ecophysiological influences and growth data to predict mycotoxin production. This could help in developing a more targeted approach to develop prevention strategies to control such carcinogenic natural metabolites that are prevalent in many staple food products. The model could also be used to predict the impact of climate change on toxin production.

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“…Bacteria, fungi, lichens, and plants produce anthraquinones and xanthones, but the best characterized biosynthetic pathways are fungal, including those that produce the emodin-derived monodictyphenone in Aspergillus nidulans (7,8) and the highly carcinogenic aflatoxin in Aspergillus parasiticus (9,10). The biosynthesis of aflatoxin begins with the production of a raw polyketide by the core polyketide synthase (PKS) PksA followed by a large number of modifications that are catalyzed by discrete tailoring/decorating enzymes (9).…”

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confidence: 99%

Elucidation of cladofulvin biosynthesis reveals a cytochrome P450 monooxygenase required for anthraquinone dimerization

Griffiths

Mesarich

Saccomanno

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

161

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Anthraquinones are a large family of secondary metabolites (SMs) that are extensively studied for their diverse biological activities. These activities are determined by functional group decorations and the formation of dimers from anthraquinone monomers. Despite their numerous medicinal qualities, very few anthraquinone biosynthetic pathways have been elucidated so far, including the enzymatic dimerization steps. In this study, we report the elucidation of the biosynthesis of cladofulvin, an asymmetrical homodimer of nataloe-emodin produced by the fungus Cladosporium fulvum. A gene cluster of 10 genes controls cladofulvin biosynthesis, which begins with the production of atrochrysone carboxylic acid by the polyketide synthase ClaG and the β-lactamase ClaF. This compound is decarboxylated by ClaH to yield emodin, which is then converted to chrysophanol hydroquinone by the reductase ClaC and the dehydratase ClaB. We show that the predicted cytochrome P450 ClaM catalyzes the dimerization of nataloe-emodin to cladofulvin. Remarkably, such dimerization dramatically increases nataloe-emodin cytotoxicity against mammalian cell lines. These findings shed light on the enzymatic mechanisms involved in anthraquinone dimerization. Future characterization of the ClaM enzyme should facilitate engineering the biosynthesis of novel, potent, dimeric anthraquinones and structurally related compound families.secondary metabolism | gene cluster | cytoxicity | emodin | nataloe-emodin

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Clustered Pathway Genes in Aflatoxin Biosynthesis

Abstract: 5Aflatoxins, a group of polyketide-derived furanocoumarins (Fig. 1), are the most toxic and carcinogenic compounds among the known mycotoxins. Among the at least 16 structurally related aflatoxins characterized, however, there are only four major aflatoxins,

Cited by 725 publications

References 119 publications

Molecular cloning and functional characterization of two CYP619 cytochrome P450s involved in biosynthesis of patulin in Aspergillus clavatus

Molecular cloning and functional characterization of two CYP619 cytochrome P450s involved in biosynthesis of patulin in Aspergillus clavatus

A systems approach to model the relationship between aflatoxin gene cluster expression, environmental factors, growth and toxin production by Aspergillus flavus

Elucidation of cladofulvin biosynthesis reveals a cytochrome P450 monooxygenase required for anthraquinone dimerization

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