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 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.
Organizational Affiliation:
1] Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA. [2] Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA.,Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.,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.,Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.
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