Inhibited KdpFABC transitions into an E1 off-cycle state.

Jakob M Silberberg, Charlott Stock, Lisa Hielkema, Robin A Corey, Jan Rheinberger, Dorith Wunnicke, Victor RA Dubach, Phillip J Stansfeld, Inga Hänelt, Cristina Paulino*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)
6 Downloads (Pure)


KdpFABC is a high-affinity prokaryotic K+ uptake system that forms a functional chimera between a channel-like subunit (KdpA) and a P-type ATPase (KdpB). At high K+ levels, KdpFABC needs to be inhibited to prevent excessive K+ accumulation to the point of toxicity. This is achieved by a phosphorylation of the serine residue in the TGES162 motif in the A domain of the pump subunit KdpB (KdpBS162-P). Here, we explore the structural basis of inhibition by KdpBS162 phosphorylation by determining the conformational landscape of KdpFABC under inhibiting and non-inhibiting conditions. Under turnover conditions, we identified a new inhibited KdpFABC state that we termed E1P tight, which is not part of the canonical Post-Albers transport cycle of P-type ATPases. It likely represents the biochemically described stalled E1P state adopted by KdpFABC upon KdpBS162 phosphorylation. The E1P tight state exhibits a compact fold of the three cytoplasmic domains and is likely adopted when the transition from high-energy E1P states to E2P states is unsuccessful. This study represents a structural characterization of a biologically relevant off-cycle state in the P-type ATPase family and supports the emerging discussion of P-type ATPase regulation by such states.


Original languageEnglish
Article numbere80988
Number of pages28
Early online date18 Oct 2022
Publication statusPublished - 11 Nov 2022


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