Construction of a Ca(2+)-gated artificial channel by fusing alamethicin with a calmodulin-derived extramembrane
Daisuke Noshiro1, Kazuhiro Sonomura, Hao-Hsin Yu
1Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Abstract:
Using native chemical ligation, we constructed a Ca(2+)-gated fusion channel protein consisting of alamethicin and the C-terminal domain of calmodulin. At pH 5.4 and in the absence of Ca(2+), this fusion protein yielded a burst-like channel current with no discrete channel conductance levels. However, Ca(2+) significantly lengthened the specific channel open state and increased the mean channel current, while Mg(2+) produced no significant changes in the channel current. On the basis of 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescent measurement, Ca(2+)-stimulated gating may be related to an increased surface hydrophobicity of the extramembrane segment of the fusion protein.
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