Molecular movement of the voltage sensor in a K channel.
The X-ray crystallographic structure of KvAP, a voltage-gated bacterial K channel, was recently published. However, the position and the molecular movement of the voltage sensor, S4, are still controversial. For example, in the crystallographic structure, S4 is located far away (>30 A) from the pore domain, whereas electrostatic experiments have suggested that S4 is located close (<8 A) to the pore domain in open channels. To test the proposed location and motion of S4 relative to the pore domain, we induced disulphide bonds between pairs of introduced cysteines: one in S4 and one in the pore domain. Several residues in S4 formed a state-dependent disulphide bond with a residue in the pore domain. Our data suggest that S4 is located close to the pore domain in a neighboring subunit. Our data also place constraints on possible models for S4 movement and are not compatible with a recently proposed KvAP model.
Broomand
Amir
A
Department of Neuroscience, The Nobel Institute for Neurophysiology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Männikkö
Roope
R
Larsson
H Peter
HP
Elinder
Fredrik
F
D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes; D010618:Phenanthrolines / Q000494:pharmacology; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D017433:Protein Structure, Secondary / Q000235:genetics; D051637:Shaker Superfamily of Potassium Channels; D014982:Xenopus laevis
D010618:Phenanthrolines; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051637:Shaker Superfamily of Potassium Channels