Activation and Complex Regulation of the Kef Potassium Efflux System During Protection of Bacteria Against Toxic Electrophiles

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

doi:10.1016/j.bpj.2010.12.763

Cited by 2 publications

(6 citation statements)

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“…2e). This is consistent with the reported apparent K M of ~4 mM in vesicles directly isolated from an E. coli Na + (K + )/H + antiporter transporter deletion strain 4 and its proposed physiology of operating in the low-to-high mM K + concentrations 7 .…”

Section: Ssm-based Electrophysiology Of Kefcsupporting

confidence: 90%

“…The regulatory domain of TrkH for example, referred to as TrkA, forms tetramers in the presence of ATP 55 . The RCK domains of KefC have been extensively analyzed in isolation and have been shown to co-purify with AMP 7,25,26 . The crystal structure of the soluble RCK domains with AMP bound are dimeric 26 , matching the KefC homodimer (Fig.…”

Section: The C-terminal Regulatory Rck Domains Of Kefcmentioning

confidence: 99%

“…In animals, the Kef K + /H + homologs belonging to the Transmembrane and coiled-coil domains 3 (TMCO3) family have been linked to eye disease 18 and cancers 19 , but their physiological role is yet to be determined 20 .KefB and KefC are the two main Kef transporters in E. coli and share 42% sequence identity (Supplementary Fig. 1) 7 . The KefB and KefC transporters from E. coli are also known as a glutathione (GSH)gated K + efflux systems as their activity are regulated by GSH 5,21 (Fig.…”

mentioning

confidence: 99%

“…KefB and KefC are the two main Kef transporters in E. coli and share 42% sequence identity (Supplementary Fig. 1) 7 . The KefB and KefC transporters from E. coli are also known as a glutathione (GSH)gated K + efflux systems as their activity are regulated by GSH 5,21 (Fig.…”

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confidence: 99%

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Structure and mechanism of the K+/H+ exchanger KefC

Gulati,

Kokane,

Perez-Boerema

et al. 2024

Nat Commun

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Intracellular potassium (K+) homeostasis is fundamental to cell viability. In addition to channels, K+ levels are maintained by various ion transporters. One major family is the proton-driven K+ efflux transporters, which in gram-negative bacteria is important for detoxification and in plants is critical for efficient photosynthesis and growth. Despite their importance, the structure and molecular basis for K+-selectivity is poorly understood. Here, we report ~3.1 Å resolution cryo-EM structures of the Escherichia coli glutathione (GSH)-gated K+ efflux transporter KefC in complex with AMP, AMP/GSH and an ion-binding variant. KefC forms a homodimer similar to the inward-facing conformation of Na+/H+ antiporter NapA. By structural assignment of a coordinated K+ ion, MD simulations, and SSM-based electrophysiology, we demonstrate how ion-binding in KefC is adapted for binding a dehydrated K+ ion. KefC harbors C-terminal regulator of K+ conductance (RCK) domains, as present in some bacterial K+-ion channels. The domain-swapped helices in the RCK domains bind AMP and GSH and they inhibit transport by directly interacting with the ion-transporter module. Taken together, we propose that KefC is activated by detachment of the RCK domains and that ion selectivity exploits the biophysical properties likewise adapted by K+-ion-channels.

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Section: Ssm-based Electrophysiology Of Kefcsupporting

confidence: 90%

Section: The C-terminal Regulatory Rck Domains Of Kefcmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Structure and mechanism of the K+/H+ exchanger KefC

Gulati,

Kokane,

Perez-Boerema

et al. 2024

Nat Commun

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“…Potassium (K + ) is the most abundant monovalent cation within living cells (1,2) and it is essential to set the membrane potential and intracellular pH (2)(3)(4)(5). As K + also emerges as an important regulator of bacterial physiology in view of its role in diverse processes (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) including biofilm formation, chemotaxis, cell to cell communication or virulence, it is therefore expected that K + transport is tightly regulated. In bacteria, the KdpDE two-component system (TCS) responds to potassium depletion by regulating the expression of the cognate high-affinity K + transporter KdpFABC (18).…”

Section: Importance Introductionmentioning

confidence: 99%

Regulation of potassium homeostasis inCaulobacter crescentus

Quintero-Yanes

Collignon

et al. 2023

Preprint

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Potassium (K+) is an essential physiological element determining membrane potential, intracellular pH, osmotic/turgor pressure, and protein synthesis in cells. Nevertheless, K+homeostasis remains poorly studied in bacteria. Here we describe the regulation of potassium uptake systems in the oligotrophic α-proteobacteriumCaulobacter crescentusknown as a model for asymmetric cell division. We show that C. crescentus can grow in concentrations from the micromolar to the millimolar range by essentially using two K+transporters to maintain potassium homeostasis, the low affinity Kup and the high affinity Kdp uptake systems. When K+is not limiting, we found that thekupgene is essential whilekdpinactivation does not impact the growth. In contrast,kdpbecomes critical but not essential andkupdispensable for growth in K+-limited environments. However, in the absence ofkdp, mutations inkupwere selected to improve growth in K+-depleted conditions, likely by improving the affinity of Kup for K+. In addition, mutations in the KdpDE two-component system, which regulateskdpABCexpression, suggest that the inner membrane sensor regulatory component KdpD works as a kinase in early stages of growth and as a phosphatase to regulate transition into stationary phase. Our data also show that KdpE is not only phosphorylated by KdpD but also by another non-cognate histidine kinase. On top of this, we determined the KdpE-dependent and independent K+transcriptome as well as the direct targets of KdpE. Together, our work illustrates how an oligotrophic bacterium responds to fluctuation in K+availability.

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Activation and Complex Regulation of the Kef Potassium Efflux System During Protection of Bacteria Against Toxic Electrophiles

Cited by 2 publications

References 0 publications

Structure and mechanism of the K+/H+ exchanger KefC

Structure and mechanism of the K+/H+ exchanger KefC

Regulation of potassium homeostasis inCaulobacter crescentus

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