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Serine phosphorylation regulates the P-type potassium pump KdpFABC

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  • Marie E Sweet, New York University School of Medicine
  • ,
  • Xihui Zhang, New York University School of Medicine
  • ,
  • Hediye Erdjument-Bromage, New York University School of Medicine
  • ,
  • Vikas Dubey, Syddansk Universitet
  • ,
  • Himanshu Khandelia, Syddansk Universitet
  • ,
  • Thomas A Neubert, New York University School of Medicine
  • ,
  • Bjørn P Pedersen
  • David L Stokes, New York University School of Medicine

KdpFABC is an ATP-dependent K+ pump that ensures bacterial survival in K+-deficient environments. Whereas transcriptional activation of kdpFABC expression is well studied, a mechanism for down-regulation when K+ levels are restored has not been described. Here, we show that KdpFABC is inhibited when cells return to a K+-rich environment. The mechanism of inhibition involves phosphorylation of Ser162 on KdpB, which can be reversed in vitro by treatment with serine phosphatase. Mutating Ser162 to Alanine produces constitutive activity, whereas the phosphomimetic Ser162Asp mutation inactivates the pump. Analyses of the transport cycle show that serine phosphorylation abolishes the K+-dependence of ATP hydrolysis and blocks the catalytic cycle after formation of the aspartyl phosphate intermediate (E1~P). This regulatory mechanism is unique amongst P-type pumps and this study furthers our understanding of how bacteria control potassium homeostasis to maintain cell volume and osmotic potential.

Antal sider19
StatusUdgivet - sep. 2020

Bibliografisk note

© 2020, Sweet et al.

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