A specialized molecular motion opens the Hv1 voltage-gated proton channel.
The Hv1 proton channel is unique among voltage-gated channels for containing the pore and gate within its voltage-sensing domain. Pore opening has been proposed to include assembly of the selectivity filter between an arginine (R3) of segment S4 and an aspartate (D1) of segment S1. We determined whether gating involves motion of S1, using Ciona intestinalis Hv1. We found that channel opening is concomitant with solution access to the pore-lining face of S1, from the cytoplasm to deep inside the pore. Voltage- and patch-clamp fluorometry showed that this involves a motion of S1 relative to its surroundings. S1 motion and the S4 motion that precedes it are each influenced by residues on the other helix, thus suggesting a dynamic interaction between S1 and S4. Our findings suggest that the S1 of Hv1 has specialized to function as part of the channel's gate.
Department of Molecular and Cell Biology, University of California, Berkeley, CA (USA).
Laetitia
L
Mony
Department of Molecular and Cell Biology, University of California, Berkeley, CA (USA).|Research Center Caesar, Bonn (Germany).
Thomas K
TK
Berger
Department of Molecular and Cell Biology, University of California, Berkeley, CA (USA).|Helen Wills Neuroscience Institute, University of California, Berkeley, CA (USA).|Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA (USA).
Ehud Y
EY
Isacoff
D000595:Amino Acid Sequence; D000818:Animals; D002938:Ciona intestinalis; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011522:Protons; D016415:Sequence Alignment
D007473:Ion Channels; D011522:Protons