Mechanism of ligand-gated potassium efflux in bacterial pathogens

Tarmo P. Roosild, Samantha Castronovo, Jess Healy, Samantha Miller, Christos Pliotas, Tim Rasmussen, Wendy Bartlett, Stuart J. Conway, Ian R. Booth

Research output: Contribution to journalArticlepeer-review


Gram negative pathogens are protected against toxic electrophilic compounds by glutathione-gated potassium efflux systems (Kef) that modulate cytoplasmic pH. We have elucidated the mechanism of gating through structural and functional analysis of Escherichia coli KefC. The revealed mechanism can explain how subtle chemical differences in glutathione derivatives can produce opposite effects on channel function. Kef channels are regulated by potassium transport and NAD-binding (KTN) domains that sense both reduced glutathione, which inhibits Kef activity, and glutathione adducts that form during electrophile detoxification and activate Kef. We find that reduced glutathione stabilizes an interdomain association between two KTN folds, whereas large adducts sterically disrupt this interaction. F441 is identified as the pivotal residue discriminating between reduced glutathione and its conjugates. We demonstrate a major structural change on the binding of an activating ligand to a KTN-domain protein. Analysis of the regulatory interactions suggests strategies to disrupt pathogen potassium and pH homeostasis.

Original languageEnglish
Pages (from-to)19784-19789
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number46
Early online date1 Nov 2010
Publication statusPublished - 16 Nov 2010


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