title: Amino acid supplementation reveals differential regulation of aflatoxin biosynthesis in Aspergillus flavus NRRL 3357 and Aspergillus parasiticus SRRC 143.
abstract: Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillus flavus and Aspergillus parasiticus. To better understand the molecular mechanisms that regulate aflatoxin production, the biosynthesis of the toxin in A. flavus and A. parasticus grown in yeast extract sucrose media supplemented with 50 mM tryptophan (Trp) were examined. Aspergillus flavus grown in the presence of 50 mM tryptophan was found to have significantly reduced aflatoxin B(1) and B(2) biosynthesis, while A. parasiticus cultures had significantly increased B(1) and G(1) biosynthesis. Microarray analysis of RNA extracted from fungi grown under these conditions revealed 77 genes that are expressed significantly different between A. flavus and A. parasiticus, including the aflatoxin biosynthetic genes aflD (nor-1), aflE (norA), and aflO (omtB). It is clear that the regulatory mechanisms of aflatoxin biosynthesis in response to Trp in A. flavus and A. parasiticus are different. These candidate genes may serve as regulatory factors of aflatoxin biosynthesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mississippi State University, PO Box 9650, Mississippi State, MS 39762, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Wilkinson
authors.forename: J
authors.initials: J
authors.lastname: Yu
authors.forename: J M
authors.initials: JM
authors.lastname: Bland
authors.forename: W C
authors.initials: WC
authors.lastname: Nierman
authors.forename: D
authors.initials: D
authors.lastname: Bhatnagar
authors.forename: T E
authors.initials: TE
authors.lastname: Cleveland
mesh_terms: D000348:Aflatoxins / Q000096:biosynthesis*; D000596:Amino Acids / Q000494:pharmacology*; D001230:Aspergillus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D001231:Aspergillus flavus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D013058:Mass Spectrometry; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013395:Sucrose / Q000494:pharmacology; D014364:Tryptophan / Q000494:pharmacology
chemical_list: D000348:Aflatoxins; D000596:Amino Acids; D013395:Sucrose; D014364:Tryptophan