Structural identification of cation binding pockets in the plasma membrane proton pump

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  • Kira Ekberg, Institut for Plantebiologi og Bioteknologi, Denmark
  • Bjørn P Pedersen
  • Danny Mollerup Sørensen, Transportbiologi, Denmark
  • Ann Kallehauge Nielsen, Institut for Plantebiologi og Bioteknologi, Denmark
  • Bjarke Veierskov, Transportbiologi, Denmark
  • Poul Nissen
  • Michael G Palmgren
  • ,
  • Morten Jeppe Buch-Pedersen, Transportbiologi, Denmark
The activity of P-type plasma membrane H(+)-ATPases is modulated by H(+) and cations, with K(+) and Ca(2+) being of physiological relevance. Using X-ray crystallography, we have located the binding site for Rb(+) as a K(+) congener, and for Tb(3+) and Ho(3+) as Ca(2+) congeners. Rb(+) is found coordinated by a conserved aspartate residue in the phosphorylation domain. A single Tb(3+) ion is identified positioned in the nucleotide-binding domain in close vicinity to the bound nucleotide. Ho(3+) ions are coordinated at two distinct sites within the H(+)-ATPase: One site is at the interface of the nucleotide-binding and phosphorylation domains, and the other is in the transmembrane domain toward the extracellular side. The identified binding sites are suggested to represent binding pockets for regulatory cations and a H(+) binding site for protons leaving the pump molecule. This implicates Ho(3+) as a novel chemical tool for identification of proton binding sites.
Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue50
Pages (from-to)21400-5
Number of pages6
ISSN0027-8424
DOIs
Publication statusPublished - 2010

    Research areas

  • Binding Sites, Cations, Cell Membrane, Crystallography, X-Ray, Genetic Complementation Test, Metals, Molecular Sequence Data, Point Mutation, Protein Structure, Tertiary, Proton Pumps, Protons, Saccharomyces cerevisiae

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