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Nat Struct Mol Biol. 2015 May;22(5):390-5. doi: 10.1038/nsmb.3002. Epub 2015 Apr 6.

Crystal structure of a light-driven sodium pump.

Author information

1
1] Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France. [2] Institut de Biologie Structurale, Centre National de la Recherche Scientifique, Grenoble, France. [3] Institut de Biologie Structurale, Commissariat à l'Énergie Atomique (CEA), Grenoble, France. [4] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [5] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany.
2
1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany. [3] Institute of Crystallography, University of Aachen (RWTH), Aachen, Germany.
3
1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany.
4
Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany.
5
European Synchrotron Radiation Facility, Grenoble, France.
6
ICS, ICS-4, Cellular Biophysics, Research Center Jülich, Jülich, Germany.
7
Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
8
1] Institute of Complex Systems (ICS), ICS-6, Structural Biochemistry, Research Center Jülich, Jülich, Germany. [2] Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
9
1] Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia. [2] ICS, ICS-5, Molecular Biophysics, Research Center Jülich, Jülich, Germany.

Abstract

Recently, the first known light-driven sodium pumps, from the microbial rhodopsin family, were discovered. We have solved the structure of one of them, Krokinobacter eikastus rhodopsin 2 (KR2), in the monomeric blue state and in two pentameric red states, at resolutions of 1.45 Å and 2.2 and 2.8 Å, respectively. The structures reveal the ion-translocation pathway and show that the sodium ion is bound outside the protein at the oligomerization interface, that the ion-release cavity is capped by a unique N-terminal α-helix and that the ion-uptake cavity is unexpectedly large and open to the surface. Obstruction of the cavity with the mutation G263F imparts KR2 with the ability to pump potassium. These results pave the way for the understanding and rational design of cation pumps with new specific properties valuable for optogenetics.

PMID:
25849142
DOI:
10.1038/nsmb.3002
[Indexed for MEDLINE]

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