α,β-Dihydroxyisovalerate dehydratase. A superoxide-sensitive enzyme

C. F. Kuo, Tadahiko Mashino, I. Fridovich

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

Increasing the intracellular flux of O2- by incubating aerobic Escherichia coli with paraquat or plumbagin markedly lowered the α,β-dihydroxyisovalerate dehydratase activity detectable in extracts from these cells. This effect was not seen in the absence of dioxygen and was exacerbated by inhibiting protein biosynthesis with chloramphenicol. These effects of paraquat and of plumbagin were both time- and concentration-dependent. Transfer of E. coli from aerobic to anaerobic conditions caused a rebound of the dehydratase activity, in the continued presence of paraquat and of chloramphenicol, indicating the presence of a mechanism for reactivating this enzyme. The instability of the dehydratase activity in cell extracts was exacerbated by selective removal of superoxide dismutase, but not of catalase, by immunoprecipitation. Addition of exogenous superoxide dismutase reversed the effect of immunoprecipitation; whereas catalase or inactive superoxide dismutase were ineffective. We conclude that the dehydratase is inactivated by O2-. This could account for the bacteriostatic effects of dioxygen and of paraquat.

Original languageEnglish
Pages (from-to)4724-4727
Number of pages4
JournalJournal of Biological Chemistry
Volume262
Issue number10
Publication statusPublished - 1987
Externally publishedYes

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Hydro-Lyases
Paraquat
Superoxides
Superoxide Dismutase
Chloramphenicol
Enzymes
Cell Extracts
Immunoprecipitation
Catalase
Escherichia coli
Oxygen
Biosynthesis
Protein Biosynthesis
Fluxes
Proteins
plumbagin

ASJC Scopus subject areas

  • Biochemistry

Cite this

α,β-Dihydroxyisovalerate dehydratase. A superoxide-sensitive enzyme. / Kuo, C. F.; Mashino, Tadahiko; Fridovich, I.

In: Journal of Biological Chemistry, Vol. 262, No. 10, 1987, p. 4724-4727.

Research output: Contribution to journalArticle

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N2 - Increasing the intracellular flux of O2- by incubating aerobic Escherichia coli with paraquat or plumbagin markedly lowered the α,β-dihydroxyisovalerate dehydratase activity detectable in extracts from these cells. This effect was not seen in the absence of dioxygen and was exacerbated by inhibiting protein biosynthesis with chloramphenicol. These effects of paraquat and of plumbagin were both time- and concentration-dependent. Transfer of E. coli from aerobic to anaerobic conditions caused a rebound of the dehydratase activity, in the continued presence of paraquat and of chloramphenicol, indicating the presence of a mechanism for reactivating this enzyme. The instability of the dehydratase activity in cell extracts was exacerbated by selective removal of superoxide dismutase, but not of catalase, by immunoprecipitation. Addition of exogenous superoxide dismutase reversed the effect of immunoprecipitation; whereas catalase or inactive superoxide dismutase were ineffective. We conclude that the dehydratase is inactivated by O2-. This could account for the bacteriostatic effects of dioxygen and of paraquat.

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