title: Multiple epoxide hydrolases in Alternaria alternata f. sp. lycopersici and their relationship to medium composition and host-specific toxin production.
abstract: The production of Alternaria alternata f. sp. lycopersici host-specific toxins (AAL toxins) and epoxide hydrolase (EH) activity were studied during the growth of this plant-pathogenic fungus in stationary liquid cultures. Media containing pectin as the primary carbon source displayed peaks of EH activity at day 4 and at day 12. When pectin was replaced by glucose, there was a single peak of EH activity at day 6. Partial characterization of the EH activities suggests the presence of three biochemically distinguishable EH activities. Two of them have a molecular mass of 25 kDa and a pI of 4.9, while the other has a molecular mass of 20 kDa and a pI of 4.7. Each of the EH activities can be distinguished by substrate preference and sensitivity to inhibitors. The EH activities present at day 6 (glucose) or day 12 (pectin) are concomitant with AAL toxin production.
authors.affiliation: Department of Entomology, University of California, Davis, California 95616, USA.
authors.forename: C
authors.initials: C
authors.lastname: Morisseau
authors.forename: B L
authors.initials: BL
authors.lastname: Ward
authors.forename: D G
authors.initials: DG
authors.lastname: Gilchrist
authors.forename: B D
authors.initials: BD
authors.lastname: Hammock
mesh_terms: D000528:Alternaria / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D002994:Clofibrate / Q000494:pharmacology; D003470:Culture Media / Q000737:chemistry; D004851:Epoxide Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology; D009183:Mycotoxins / Q000096:biosynthesis*; D010368:Pectins / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D013379:Substrate Specificity
chemical_list: D003470:Culture Media; D009183:Mycotoxins; D010368:Pectins; D004851:Epoxide Hydrolases; D002994:Clofibrate; D005947:Glucose