Biochemical and physiological properties of rhodopsin regenerated with 11-cis-6-ring- and 7-ring-retinals.
Phototransduction is initiated by the photoisomerization of rhodopsin (Rho) chromophore 11-cis-retinylidene to all-trans-retinylidene. Here, using Rho regenerated with retinal analogs with different ring sizes, which prevent isomerization around the C(11)=C(12) double bond, the activation mechanism of this G-protein-coupled receptor was investigated. We demonstrate that 11-cis-7-ring-Rho does not activate G-protein in vivo and in vitro, and that it does not isomerize along other double bonds, suggesting that it fits tightly into the binding site of opsin. In contrast, bleaching 11-cis-6-ring-Rho modestly activates phototransduction in vivo and at low pH in vitro. These results reveal that partial activation is caused by isomerization along other double bonds in more rigid 6-locked retinal isomers and protonation of key residues by lowering pH in 11-cis-6-ring-Rhos. Full activation is not achieved, because isomerization does not induce a complete set of conformational rearrangements of Rho. These results with 6- and 7-ring-constrained retinoids provide new insights into Rho activation and suggest a potential use of locked retinals, particularly 11-cis-7-ring-retinal, to inactivate opsin in some retinal degeneration diseases.
Kuksa
Vladimir
V
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.
Bartl
Franz
F
Institut für Medizinische Physik und Biophysik, Universitätsklinikum Charité, Humboldt Universität zu Berlin, D-10098 Berlin, Germany.
Maeda
Tadao
T
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.
Jang
Geeng-Fu
GF
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.
Ritter
Eglof
E
Institut für Medizinische Physik und Biophysik, Universitätsklinikum Charité, Humboldt Universität zu Berlin, D-10098 Berlin, Germany.
Heck
Martin
M
Institut für Medizinische Physik und Biophysik, Universitätsklinikum Charité, Humboldt Universität zu Berlin, D-10098 Berlin, Germany.
Preston Van Hooser
J
J
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.
Liang
Yan
Y
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.
Filipek
Sławomir
S
International Institute of Molecular and Cell Biology and Department of Chemistry, University of Warsaw, Warsaw PI-02109, Poland.
Gelb
Michael H
MH
Department of Chemistry, University of Washington, Seattle, Washington 98195, and.|Department of Biochemistry, University of Washington, Seattle, Washington 98195.
Hofmann
Klaus Peter
KP
Institut für Medizinische Physik und Biophysik, Universitätsklinikum Charité, Humboldt Universität zu Berlin, D-10098 Berlin, Germany.
Palczewski
Krzysztof
K
Department of Ophthalmology, University of Washington, Seattle, Washington 98195.|Department of Pharmacology, University of Washington, Seattle, Washington 98195.|Department of Chemistry, University of Washington, Seattle, Washington 98195, and.
D000818:Animals; D006863:Hydrogen-Ion Concentration; D051379:Mice; D010766:Phosphorylation; D011487:Protein Conformation; D012162:Retinal Degeneration; D012172:Retinaldehyde / Q000378:metabolism*; D012243:Rhodopsin / Q000096:biosynthesis* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
D012243:Rhodopsin; D012172:Retinaldehyde