Enzymatic characterization of scytalone dehydratase Val75Met variant found in melanin biosynthesis dehydratase inhibitor (MBI-D) resistant strains of the rice blast fungus

Naoki Yamada, Takayuki Motoyama, Masayoshi Nakasako, Shinzo Kagabu, Toshiaki Kudo, Isamu Yamaguchi

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Carpropamid ((1RS,3SR)-2,2-dichloro-N-[(R)-1-(4-chlorophenyl)ethyl]-1- ethyl-3-methylcyclopropanecarboxamide) is a potent chemical against the rice blast fungus, Pyricularia oryzae. In 2001, isolates of the fungus with reduced sensitivity to this fungicide appeared in Saga Prefecture of Japan and were regarded as a potential threat to rice protection by carpropamid. The cause of the resistance has been identified genetically as a point mutation resulting in the Val75Met change in scytalone dehydratase, the primary target of the fungicide. We constructed an overexpression system of the variant enzyme and characterized the kinetics in the catalysis and the inhibition by carpropamid isomers. The variant enzyme retained a significant level of enzymatic activity. Inhibition of the variant enzyme by carpropamid was more than 200-fold reduced in comparison with that of the wild-type. Based on the results, here we propose possible mechanisms of the carpropamid-resistance of the variant enzyme in retaining the normal enzymatic activity.

Original languageEnglish
Pages (from-to)615-621
Number of pages7
JournalBioscience, Biotechnology and Biochemistry
Volume68
Issue number3
DOIs
Publication statusPublished - 2004 Mar

Keywords

  • Carpropamid
  • Enzymatic kinetics
  • Melanin biosynthesis dehydratase inhibitor
  • Rice blast fungus
  • Scytalone dehydratase

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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