Mechanism of ligand-gated potassium efflux in bacterial pathogens

作者：Roosild Tarmo P^*; Castronovo Samantha; Healy Jess; Miller Samantha; Pliotas Christos; Rasmussen Tim; Bartlett Wendy; Conway Stuart J; Booth Ian R

来源：Proceedings of the National Academy of Sciences, 2010, 107(46): 19784-19789.

DOI：10.1073/pnas.1012716107

• channel regulation
• KTN structure

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.

• 出版日期2010-11-16
• 单位河北医科大学