Multiple epoxide hydrolases in Alternaria alternata f. sp. lycopersici and their relationship to medium composition and host-specific toxin production.
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.
Morisseau
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C
Department of Entomology, University of California, Davis, California 95616, USA.
Ward
B L
BL
Gilchrist
D G
DG
Hammock
B D
BD
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
D003470:Culture Media; D009183:Mycotoxins; D010368:Pectins; D004851:Epoxide Hydrolases; D002994:Clofibrate; D005947:Glucose