New Insights into the Conversion of Versicolorin A in the Biosynthesis of Aflatoxin B1.
J Am Chem Soc
; 137(34): 10867-9, 2015 Sep 02.
Article
en En
| MEDLINE
| ID: mdl-26266881
ABSTRACT
A crucial and enigmatic step in the complex biosynthesis of aflatoxin B1 is the oxidative rearrangement of versicolorin A to demethylsterigmatocystin. This step is thought to proceed by an oxidation-reduction-oxidation sequence, in which the NADPH-dependent oxidoreductase AflM catalyzes the enclosed reduction step. AflM from Aspergillus parasiticus, after heterologous production in E. coli and purification, however, catalyzed the reduction of the hydroquinoid form of the starting compound versicolorin A (25% conversion) to a so far unknown product of aflatoxin biosynthesis. The asymmetric reduction of emodin hydroquinone to (R)-3,8,9,10-tetrahydroxy-6-methyl-3,4-dihydroanthracen-1(2H)-one (up to 82% for AflM) has also been observed in previous studies using MdpC from Aspergillus nidulans (monodictyphenone biosynthetic gene cluster). The first (nonenzymatic) reduction of emodin to emodin hydroquinone, for example with sodium dithionite, is obligatory for the enzymatic reduction by AflM or MdpC. These results imply an unprecedented role of AflM in the complex enzymatic network of aflatoxin biosynthesis.
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1
Banco de datos:
MEDLINE
Asunto principal:
Antraquinonas
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Aflatoxina B1
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NADH NADPH Oxidorreductasas
Idioma:
En
Año:
2015
Tipo del documento:
Article