TY - JOUR
T1 - Photochemistry and photoinduced proton-transfer by pharaonis phoborhodopsin
AU - Kamo, N.
AU - Shimono, K.
AU - Iwamoto, M.
AU - Sudo, Y.
PY - 2001/11
Y1 - 2001/11
N2 - Phoborhodopsin (pR or sensory rhodopsin II, sRII) is a photoreceptor of the negative phototaxis of Halobacterium salinarum, and pharaonis phoborhodopsin (ppR or pharaonis sensory rhodopsin II, psRII) is a corresponding protein of Natronobacterium pharaonis. The photocycle of ppR is essentially as follows: ppR(498) → ppRK(∼540) → ppRKL(512) → ppRL(488) → ppRM(390) → ppRo(560) → ppR (numbers in parenthesis denote the maximum absorbance). The photocycle is very similar to that of bacteriorhodopsin, but the rate of initial pigment recovery is about two-orders of magnitude slower. By low-temperature spectroscopy, two K-intermediates were found but the L intermediate was not detected. The lack of L indicates extraordinary stability of K at low temperature, ppRM is photoactive similar to M of bR. The ground state ppR contains only all-trans retinal whereas ppRM and ppRo contain 13-cis and all-trans, respectively. ppR has the ability of light-induced proton transport from the inside to the outside. Proton uptake occurs at the formation of ppRo and the release at its decay. ppR associates with its transducer and this complex transmits a signal to the cytoplasm. The proton transport ability is lost when the complex forms, but the proton uptake and release still occur, suggesting that the proton movement is non-electrogenic (release and uptake occur from the same side). The stoichiometry of the complex between ppR and the transducer is 1 : 1. ppR or pR has absorption maximum at ∼500 nm, which is blue-shifted from those of other archaeal rhodopsins. The molecular mechanism of this color regulation is not yet solved.
AB - Phoborhodopsin (pR or sensory rhodopsin II, sRII) is a photoreceptor of the negative phototaxis of Halobacterium salinarum, and pharaonis phoborhodopsin (ppR or pharaonis sensory rhodopsin II, psRII) is a corresponding protein of Natronobacterium pharaonis. The photocycle of ppR is essentially as follows: ppR(498) → ppRK(∼540) → ppRKL(512) → ppRL(488) → ppRM(390) → ppRo(560) → ppR (numbers in parenthesis denote the maximum absorbance). The photocycle is very similar to that of bacteriorhodopsin, but the rate of initial pigment recovery is about two-orders of magnitude slower. By low-temperature spectroscopy, two K-intermediates were found but the L intermediate was not detected. The lack of L indicates extraordinary stability of K at low temperature, ppRM is photoactive similar to M of bR. The ground state ppR contains only all-trans retinal whereas ppRM and ppRo contain 13-cis and all-trans, respectively. ppR has the ability of light-induced proton transport from the inside to the outside. Proton uptake occurs at the formation of ppRo and the release at its decay. ppR associates with its transducer and this complex transmits a signal to the cytoplasm. The proton transport ability is lost when the complex forms, but the proton uptake and release still occur, suggesting that the proton movement is non-electrogenic (release and uptake occur from the same side). The stoichiometry of the complex between ppR and the transducer is 1 : 1. ppR or pR has absorption maximum at ∼500 nm, which is blue-shifted from those of other archaeal rhodopsins. The molecular mechanism of this color regulation is not yet solved.
KW - Phoborhodopsin
KW - Photocycle
KW - Photoinduced proton transfer
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U2 - 10.1023/A:1013187403599
DO - 10.1023/A:1013187403599
M3 - Review article
C2 - 11743872
AN - SCOPUS:0035498353
VL - 66
SP - 1277
EP - 1282
JO - Biochemistry. Biokhimiia
JF - Biochemistry. Biokhimiia
SN - 0006-2979
IS - 11
ER -