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

TY - JOUR

T1 - Structural identification of cation binding pockets in the plasma membrane proton pump

AU - Ekberg, Kira

AU - Pedersen, Bjørn P

AU - Sørensen, Danny Mollerup

AU - Nielsen, Ann Kallehauge

AU - Veierskov, Bjarke

AU - Nissen, Poul

AU - Palmgren, Michael G

AU - Buch-Pedersen, Morten Jeppe

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

KW - Binding Sites

KW - Cations

KW - Cell Membrane

KW - Crystallography, X-Ray

KW - Genetic Complementation Test

KW - Metals

KW - Molecular Sequence Data

KW - Point Mutation

KW - Protein Structure, Tertiary

KW - Proton Pumps

KW - Protons

KW - Saccharomyces cerevisiae

U2 - 10.1073/pnas.1010416107

DO - 10.1073/pnas.1010416107

M3 - Journal article

C2 - 21098259

SN - 0027-8424

VL - 107

SP - 21400

EP - 21405

JO - Proceedings of the National Academy of Sciences (PNAS)

JF - Proceedings of the National Academy of Sciences (PNAS)

IS - 50

ER -