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Evidence for the archaebacterial‐type conformation about the bond between the β‐ionone ring and the polyene chain of the chromophore retinal in chlamyrhodopsin
Author(s) -
Sakamoto Masaru,
Wada Akimori,
Akai Akiko,
Ito Masayoshi,
Goshima Takehiko,
Takahashi Tetsuo
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01004-7
Subject(s) - rhodopsin , polyene , chlamydomonas reinhardtii , chlamydomonas , chromophore , retinal , retinaldehyde , stereochemistry , chemistry , ionone , biology , biochemistry , photochemistry , gene , mutant
Previous studies using retinal analogs (Wada, A., Sakai, M., Kinumi, T., Tsujimoto, K., Yamauchi, M. and Ito, M. (1994) J. Org. Chem. 59, 6992–6997; Wada, A., Sakai, M., Imamoto, Y., Shichida., Y., Yoshizawa, T. and Ito, M. (1993) Chem. Pharm. Bull. 41, 793–795) revealed that both retinochrome and visual pigments share a common chromophoric conformation in which the ring region of retinal is twisted ca. 50° with respect to the plane of the polyene chain, suggesting a highly conserved 6‐s‐ cis conformation throughout rhodopsin‐like pigments in animals. By contrast, 6‐s‐ trans conformation was commonly observed or suggested in archaebacterial rhodopsins examined thus far. Here we have reconstituted in vivo both the photoreceptor for photobehavioral responses of the unicellular alga Chlamydomonas reinhardtii and the second archaeal sensory photoreceptor phoborhodopsin from a series of retinal analogs. Results exclusively point to the conclusion that in both photoreceptors retinal has the coplanar 6‐s‐ trans conformation, though recent molecular cloning studies revealed no homology between Chlamydomonas photoreceptor (chlamyrhodopsin) and archaeal rhodopsins.