Color-discriminating retinal configurations of sensory rhodopsin I by photo-irradiation solid-state NMR spectroscopy.
SRI (sensory rhodopsin I) can discriminate multiple colors for the attractant and repellent phototaxis. Studies aimed at revealing the color-dependent mechanism show that SRI is a challenging system not only in photobiology but also in photochemistry. During the photoreaction of SRI, an M-intermediate (attractant) transforms into a P-intermediate (repellent) by absorbing blue light. Consequently, SRI then cycles back to the G-state. The photoreactions were monitored with the (13)C NMR signals of [20-(13)C]retnal-SrSRI using in situ photo-irradiation solid-state NMR spectroscopy. The M-intermediate was trapped at -40 °C by illumination at 520 nm. It was transformed into the P-intermediate by subsequent illumination at 365 nm. These results reveal that the G-state could be directly transformed to the P-intermediate by illumination at 365 nm. Thus, the stationary trapped M- and P-intermediates are responsible for positive and negative phototaxis, respectively.
Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan).
Hiroki
H
Yomoda
Yoshiteru
Y
Makino
Yuya
Y
Tomonaga
Tetsurou
T
Hidaka
Izuru
I
Kawamura
Takashi
T
Okitsu
Akimori
A
Wada
Yuki
Y
Sudo
Akira
A
Naito
D002247:Carbon Isotopes / Q000737:chemistry; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D012160:Retina / Q000378:metabolism; D025603:Sensory Rhodopsins / Q000737:chemistry*; D013696:Temperature
D002247:Carbon Isotopes; D025603:Sensory Rhodopsins
biological activity; photo-irradiation; retinal chromophores; sensory rhodopsin I; solid-state NMR spectroscopy