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Free keywords:
voltage-dependence; bacteriorhodopsin; chlamydomonas; ; rhodopsin; photoreceptor; phototaxis; resolution; protein
Abstract:
Phototaxis and photophobic responses of green algae are mediated by rhodopsins with microbial-type chromophores. We report a complementary DNA sequence in the green alga Chlamydomonas reinhardtii that encodes a microbial opsin- related protein, which we term Channelopsin-1. The hydrophobic core region of the protein shows homology to the light- activated proton pump bacteriorhodopsin. Expression of Channelopsin-1, or only the hydrophobic core, in Xenopus laevis oocytes in the presence of all-trans retinal produces a light- gated conductance that shows characteristics of a channel selectively permeable for protons. We suggest that Channelrhodopsins are involved in phototaxis of green algae.
