title: Examination of fungal stress response genes using Saccharomyces cerevisiae as a model system: targeting genes affecting aflatoxin biosynthesis by Aspergillus flavus Link.
abstract: Saccharomyces cerevisiae served as a model fungal system to examine functional genomics of oxidative stress responses and reactions to test antioxidant compounds. Twenty-two strains of S. cerevisiae, including a broad spectrum of singular gene deletion mutants, were exposed to hydrogen peroxide (H2O2) to examine phenotypic response to oxidative stress. Responses of particular mutants treated with gallic, tannic or caffeic acids, or methyl gallate, during H2O2 exposure, indicated that these compounds alleviated oxidative stress. These compounds are also potent inhibitors of aflatoxin biosynthesis in Aspergillus flavus. To gain further insights into a potential link between oxidative stress and aflatoxin biosynthesis, 43 orthologs of S. cerevisiae genes involved in gene regulation, signal transduction (e.g., SHO1, HOG1, etc.) and antioxidation (e.g., CTT1, CTA1, etc.) were identified in an A. flavus expressed sequence tag library. A successful exemplary functional complementation of an antioxidative stress gene from A. flavus, mitochondrial superoxide dismutase (sodA), in a sod2Delta yeast mutant further supported the potential of S. cerevisiae deletion mutants to serve as a model system to study A. flavus. Use of this system to further examine functional genomics of oxidative stress in aflatoxigenesis and reduction of aflatoxin biosynthesis by antioxidants is discussed.
authors.affiliation: Plant Mycotoxin Research Unit, Western Regional Research Center, USDA-ARS, 800 Buchanan St., Albany, CA 94710, USA.
authors.forename: Jong H
authors.initials: JH
authors.lastname: Kim
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Campbell
authors.forename: Jiujiang
authors.initials: J
authors.lastname: Yu
authors.forename: Noreen
authors.initials: N
authors.lastname: Mahoney
authors.forename: Kathleen L
authors.initials: KL
authors.lastname: Chan
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Molyneux
authors.forename: Deepak
authors.initials: D
authors.lastname: Bhatnagar
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Cleveland
mesh_terms: D000348:Aflatoxins / Q000096:biosynthesis; D000975:Antioxidants / Q000494:pharmacology; D001231:Aspergillus flavus / Q000235:genetics / Q000378:metabolism*; D002109:Caffeic Acids / Q000494:pharmacology; D020224:Expressed Sequence Tags; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D018390:Gene Targeting; D005798:Genes, Bacterial; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics; D013634:Tannins / Q000494:pharmacology
chemical_list: D000348:Aflatoxins; D000975:Antioxidants; D002109:Caffeic Acids; D013634:Tannins; C052082:methyl gallate; D005707:Gallic Acid; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; C040048:caffeic acid