A shaker K+ channel with a miniature engineered voltage sensor.
Voltage-gated ion channels sense transmembrane voltage changes via a paddle-shaped motif that includes the C-terminal part of the third transmembrane segment (S3b) and the N-terminal part of the fourth segment ((NT)S4) that harbors voltage-sensing arginines. Here, we find that residue triplets in S3b and (NT)S4 can be deleted individually, or even in some combinations, without compromising the channels' basic voltage-gating capability. Thus, a high degree of complementarity between these S3b and (NT)S4 regions is not required for basic voltage gating per se. Remarkably, the voltage-gated Shaker K(+) channel remains voltage gated after a 43 residue paddle sequence is replaced by a glycine triplet. Therefore, the paddle motif comprises a minimal core that suffices to confer voltage gating in the physiological voltage range, and a larger, modulatory part. Our study also shows that the hydrophobic residues between the voltage-sensing arginines help set the sensor's characteristic chemical equilibrium between activated and deactivated states.
Xu
Yanping
Y
Department of Physiology, Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
Ramu
Yajamana
Y
Lu
Zhe
Z
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000737:chemistry / Q000378:metabolism; D055724:Electrophysiological Phenomena; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D015202:Protein Engineering; D051381:Rats; D051637:Shaker Superfamily of Potassium Channels / Q000737:chemistry* / Q000378:metabolism*
D054815:Cyclic Nucleotide-Gated Cation Channels; D051637:Shaker Superfamily of Potassium Channels