Potassium as an Intrinsic Uncoupler of the Plasma Membrane H+-ATPase

The plant plasma membrane proton pump (H+-ATPase) is stimulated by potassium, but it has remained unclear whether potassium is actually transported by the pump or whether it serves other roles. We now show that K+ is bound to the proton pump at a site involving Asp617 in the cytoplasmic phosphorylat...

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Bibliographic Details
Published in:The Journal of biological chemistry 2006-12, Vol.281 (50), p.38285-38292
Main Authors: Buch-Pedersen, Morten J., Rudashevskaya, Elena L., Berner, Torben S., Venema, Kees, Palmgren, Michael G.
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Cations, Monovalent
Cell Membrane - enzymology
Hydrolysis
Mutagenesis, Site-Directed
Phosphorylation
Potassium - metabolism
Protein Conformation
Proton-Translocating ATPases - genetics
Proton-Translocating ATPases - metabolism
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Summary:The plant plasma membrane proton pump (H+-ATPase) is stimulated by potassium, but it has remained unclear whether potassium is actually transported by the pump or whether it serves other roles. We now show that K+ is bound to the proton pump at a site involving Asp617 in the cytoplasmic phosphorylation domain, from where it is unlikely to be transported. Binding of K+ to this site can induce dephosphorylation of the phosphorylated E1P reaction cycle intermediate by a mechanism involving Glu184 in the conserved TGES motif of the pump actuator domain. Our data identify K+ as an intrinsic uncoupler of the proton pump and suggest a mechanism for control of the H+/ATP coupling ratio. K+-induced dephosphorylation of E1P may serve regulatory purposes and play a role in negative regulation of the transmembrane electrochemical gradient under cellular conditions where E1P is accumulating.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M604781200