Enhanced sensitivity of Streptomyces seoulensis to menadione by superfluous lipoamide dehydrogenase.
Lipoamide dehydrogenase from Streptomyces seoulensis could facilitate menadione-mediated cytochrome c reduction, which was mostly inhibited by superoxide dismutase, indicating the obvious involvement of superoxide radical anion. In this reaction, the production of superoxide radical anion occurred via a menadione semiquinone radical anion. When exposed to menadione, lipoamide dehydrogenase-overexpressing cells showed a much lower survival rate with a concomitant decrease of intracellular protein thiol than the wild-type strain. These results suggest that lipoamide dehydrogenase is a facilitating agent in the redox cycling of quinone compounds in vivo as well as in vitro and could inevitably increase the potential toxicity of the compounds.
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Laboratory of Biophysics, Department of Microbiology, College of Natural Sciences, and Research Center for Molecular Microbiology, Seoul National University, Seoul, South Korea.
Kang
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D008058:Dihydrolipoamide Dehydrogenase / Q000302:isolation & purification / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D010084:Oxidation-Reduction; D011809:Quinones / Q000378:metabolism; D013302:Streptomyces / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis; D014812:Vitamin K / Q000494:pharmacology* / Q000633:toxicity
D011809:Quinones; D014812:Vitamin K; D013482:Superoxide Dismutase; D008058:Dihydrolipoamide Dehydrogenase