KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity

Lisbeth Kongsbak Lyngberg, Jess Healy, Wendy Bartlett, Samantha Miller, Stuart J Conway, Ian Rylance Booth, Tim Rasmussen

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Escherichia coli and many other Gram-negative pathogenic bacteria protect themselves from the toxic effects of electrophilic compounds by using a potassium efflux system (Kef). Potassium efflux is coupled to the influx of protons, which lowers the internal pH and results in immediate protection. The activity of the Kef system is subject to complex regulation by glutathione and its S conjugates. Full activation of KefC requires a soluble ancillary protein, KefF. This protein has structural similarities to oxidoreductases, including human quinone reductases 1 and 2. Here, we show that KefF has enzymatic activity as an oxidoreductase, in addition to its role as the KefC activator. It accepts NADH and NADPH as electron donors and quinones and ferricyanide (in addition to other compounds) as acceptors. However, typical electrophilic activators of the Kef system, e.g., N-ethyl maleimide, are not substrates. If the enzymatic activity is disrupted by site-directed mutagenesis while retaining structural integrity, KefF is still able to activate the Kef system, showing that the role as an activator is independent of the enzyme activity. Potassium efflux assays show that electrophilic quinones are able to activate the Kef system by forming S conjugates with glutathione. Therefore, it appears that the enzymatic activity of KefF diminishes the redox toxicity of quinones, in parallel with the protection afforded by activation of the Kef system.

Original languageEnglish
Pages (from-to)4925-4932
Number of pages8
JournalJournal of Bacteriology
Volume193
Issue number18
Early online date8 Jul 2011
DOIs
Publication statusPublished - Sep 2011

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Quinones
Potassium
Oxidoreductases
Glutathione
Poisons
Site-Directed Mutagenesis
Gram-Negative Bacteria
NADP
NAD
Oxidation-Reduction
Protons
Proteins
Electrons
Escherichia coli
Enzymes
benzoquinone

Cite this

Lyngberg, L. K., Healy, J., Bartlett, W., Miller, S., Conway, S. J., Booth, I. R., & Rasmussen, T. (2011). KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity. Journal of Bacteriology, 193(18), 4925-4932. https://doi.org/10.1128/JB.05272-11

KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity. / Lyngberg, Lisbeth Kongsbak; Healy, Jess; Bartlett, Wendy; Miller, Samantha; Conway, Stuart J; Booth, Ian Rylance; Rasmussen, Tim.

In: Journal of Bacteriology, Vol. 193, No. 18, 09.2011, p. 4925-4932.

Research output: Contribution to journalArticle

Lyngberg, LK, Healy, J, Bartlett, W, Miller, S, Conway, SJ, Booth, IR & Rasmussen, T 2011, 'KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity', Journal of Bacteriology, vol. 193, no. 18, pp. 4925-4932. https://doi.org/10.1128/JB.05272-11
Lyngberg, Lisbeth Kongsbak ; Healy, Jess ; Bartlett, Wendy ; Miller, Samantha ; Conway, Stuart J ; Booth, Ian Rylance ; Rasmussen, Tim. / KefF, the regulatory subunit of the potassium efflux system KefC, shows quinone oxidoreductase activity. In: Journal of Bacteriology. 2011 ; Vol. 193, No. 18. pp. 4925-4932.
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