Extent of voltage sensor movement during gating of shaker K+ channels.
Voltage-driven activation of Kv channels results from conformational changes of four voltage sensor domains (VSDs) that surround the K(+) selective pore domain. How the VSD helices rearrange during gating is an area of active research. Luminescence resonance energy transfer (LRET) is a powerful spectroscopic ruler uniquely suitable for addressing the conformational trajectory of these helices. Using a geometric analysis of numerous LRET measurements, we were able to estimate LRET probe positions relative to existing structural models. The experimental movement of helix S4 does not support a large 15-20 A transmembrane "paddle-type" movement or a near-zero A vertical "transporter-type" model. Rather, our measurements demonstrate a moderate S4 displacement of 10 +/- 5 A, with a vertical component of 5 +/- 2 A. The S3 segment moves 2 +/- 1 A in the opposite direction and is therefore not moving as an S3-S4 rigid body.
Posson
David J
DJ
Department of Physics and Biophysics, University of Illinois Urbana-Champaign, Urbana IL 61801, USA.
Selvin
Paul R
PR
D000595:Amino Acid Sequence; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D015640:Ion Channel Gating / Q000502:physiology*; D008051:Lipid Bilayers; D008564:Membrane Potentials / Q000502:physiology / Q000528:radiation effects; D008954:Models, Biological; D008958:Models, Molecular; D009865:Oocytes; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051637:Shaker Superfamily of Potassium Channels / Q000502:physiology*; D014982:Xenopus laevis
D008051:Lipid Bilayers; D051637:Shaker Superfamily of Potassium Channels; D011188:Potassium