Structural mechanism of voltage-dependent gating in an isolated voltage-sensing domain.
The transduction of transmembrane electric fields into protein motion has an essential role in the generation and propagation of cellular signals. Voltage-sensing domains (VSDs) carry out these functions through reorientations of positive charges in the S4 helix. Here, we determined crystal structures of the Ciona intestinalis VSD (Ci-VSD) in putatively active and resting conformations. S4 undergoes an ~5-Å displacement along its main axis, accompanied by an ~60° rotation. This movement is stabilized by an exchange in countercharge partners in helices S1 and S3 that generates an estimated net charge transfer of ~1 eo. Gating charges move relative to a ''hydrophobic gasket' that electrically divides intra- and extracellular compartments. EPR spectroscopy confirms the limited nature of S4 movement in a membrane environment. These results provide an explicit mechanism for voltage sensing and set the basis for electromechanical coupling in voltage-dependent enzymes and ion channels.
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
Qufei
Q
Li
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
Sherry
S
Wanderling
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
Marcin
M
Paduch
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
David
D
Medovoy
Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Abhishek
A
Singharoy
Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Ryan
R
McGreevy
Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.
Carlos A
CA
Villalba-Galea
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
Raymond E
RE
Hulse
1] Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA. [2] Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA.
Benoît
B
Roux
1] Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. [2] Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Klaus
K
Schulten
1] Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA. [2] Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA.
Anthony
A
Kossiakoff
1] Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA. [2] Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA.
Eduardo
E
Perozo
D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002938:Ciona intestinalis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D004594:Electrophysiology; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D014982:Xenopus laevis / Q000378:metabolism