Characterization of epoxide hydrolase activity in Alternaria alternata f. sp. lycopersici. Possible involvement in toxin production (Epoxide hydrolase in Alternaria alternata f. sp. lycopersici)

Franck Pinot, Eloisa D. Caldas, Christina Schmidt, David G. Gilchrist, A. D. Jones, Carl K. Winter, Bruce D. Hammock

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Using trans-diphenylpropane oxide (tDPPO) as a substrate, we measured epoxide hydrolase (EH) activity in subcellular fractions of Alternaria alternata f. sp. lycopersici (Aal), a fungus that produces host-specific toxins. The activity was mainly (>99.5%) located in the soluble fraction (100,000 x g supernatant) with the optimum pH at 7.4. An increase of toxin production between days 3 and 9 found in a Aal liquid culture over a 15 days period was concomitant with a period of high EH activity. EH activity remained constant during the same period in an Alternaria alternata culture, a fungus which does not produce toxin. In vivo treatment of Aal culture with the peroxisome proliferator clofibrate stimulated EH activity by 83% and enhanced toxin production 6.3 fold. Both 4-fluorochalcone oxide (4-FCO) and (2S,3S)-(-)-3-(4-nitrophenyl)-glycidol (SS-NPG) inhibited EH activity in vitro with a I50 of 23 ± 1 μM and 72 ± 19 μM, respectively. The possible physiological substrate 9,10-epoxystearic acid was hydrolyzed more efficiently by Aal sEH than the model substrates trans- and cis-stilbene oxide (TSO and CSO) and trans- and cis-diphenylpropane oxide (tDPPO and cDPPO).

Original languageEnglish (US)
Pages (from-to)51-58
Number of pages8
JournalMycopathologia
Volume140
Issue number1
DOIs
StatePublished - 1997

Keywords

  • AAL toxins
  • Epoxide hydrolase
  • Fungus
  • Inhibitor

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Plant Science

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