Chromophore of Bacteriorhodopsin is Closer to the Cytoplasmic Surface of Purple Membrane

Otomo, Jun; Tomioka, Akihiro; Kinosita, Kazuhiko; Miyata, Hidetake; Takenaka, Yuko; Kouyama, Tsutomu; Ikegami, Akira

doi:10.1016/s0006-3495(88)82930-8

Cited by 13 publications

(7 citation statements)

References 27 publications

(40 reference statements)

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“…Separate data are therefore needed to by the NH + group during all-trans-13 cis isomerization (Keszthelyi, 1984). Models of bR structure locate the Schiff-base at 1/3 of membrane thickness from the internal surface of the membrane (Stoeckenius et al, 1979;Otomi et al, 1988). This is reproduced by the data d4 = 3.1 nm and d5 = 1.5 nm.…”

Section: Discussion Of the Distancesmentioning

confidence: 87%

Protein electric response signals from dielectrically polarized systems

Keszthelyi

Ormos

1989

J. Membrain Biol.

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Section: Discussion Of the Distancesmentioning

confidence: 87%

Protein electric response signals from dielectrically polarized systems

Keszthelyi

Ormos

1989

J. Membrain Biol.

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“…From the initial fluorescence decay rate, they calculated a distance of 10 A ± 3 between the center of the chromophore and the cytoplasmic surface. Most models of the BR folding pattern place Lys-216 near the middle of the membrane and since the retinal has a 200 tilt, the data of Otomo et al (1988) suggests that the chromophore is tilted toward the cytoplasm (Fig. 6 A).…”

Section: Discussionmentioning

confidence: 99%

Orientation of the protonated retinal Schiff base group in bacteriorhodopsin from absorption linear dichroism

Lin

Mathies

1989

Biophysical Journal

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Linear dichroism experiments are performed on light-adapted bacteriorhodopsin (BR568) films containing native retinal (A1) and its 3,4-dehydroretinal (A2) analogue to measure the angle between the chromophore transition dipole moment and the membrane normal. QCFF/pi calculations show that the angle between the transition moment and the long axis of the polyene is changed by 3.4 degrees when the C3-C4 bond is unsaturated. The difference vector between the two transition moments points in the same direction as the Schiff base (N----H) bond for the all-trans BR568 chromophore. Because the plane of the chromophore is perpendicular to the membrane plane, a comparison of the transition moment orientations in the A1- and A2-pigments enables us to determine the orientation of the N----H bond with respect to the absolute chromophore (N----C5 vector) orientation. The angles of the transition moments are 70.3 degrees +/- 0.4 degrees and 67.8 degrees +/- 0.4 degrees for the A1- and A2-pigments, respectively. The fact that the change in the transition moment angle (2.5 degrees) is close to the predicted 3.4 degrees supports the idea that the chromophore plane is nearly perpendicular to the membrane plane. The decreased transition moment angle in the A2-analogue requires that the N----H bond and the N----C5 vector point toward the same membrane surface. Available results indicate that the N----C5 vector points toward the exterior in BR568. With this assignment, we conclude that the N----H bond points toward the exterior surface and its most likely counterion Asp-212. This information makes possible the construction of a computer graphics model for the active site in BR568.

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“…Fluorescence energy transfer experiments, on the other hand, indicated that the chromophore is at a depth of about 10 Á from the cytoplasmic side of the membrane (Kouyama et al, 1988a;Otomo et al, 1988;Tsetlin et al, 1983). On the basis of surface-enhanced resonance Raman experiments, it was concluded that the chromophore is only 6 Á away from the extracellular surface (Nabiev et al, 1985).…”

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confidence: 99%

Transmembrane location of retinal in bacteriorhodopsin by neutron diffraction

Hauss¹,

Grzesiek²,

Otto³

et al. 1990

Biochemistry

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The transmembrane location of the chromophore of bacteriorhodopsin was obtained by neutron diffraction on oriented stacks of purple membranes. Two selectively deuterated retinals were synthesized and incorporated in bacteriorhodopsin by using the retinal- mutant JW5: retinal-d11 (D11) contained 11 deuterons in the cyclohexene ring, and retinal-d5 (D5) had 5 deuterons as close as possible to the Schiff base end of the chromophore. The membrane stacks had a lamellar spacing of 53.1 A at 86% relative humidity. Five orders were observed in the lamellar diffraction pattern of the D11, D5, and nondeuterated reference samples. The reflections were phased by D2O-H2O exchange. The absolute values of the structure factors were nonlinear functions of the D2O content, suggesting that the coherently scattering domains consisted of asymmetric membrane stacks. The centers of deuteration were determined from the observed intensity differences between labeled and unlabeled samples by using model calculations and Fourier difference methods. With the origin of the coordinate system defined midway between consecutive intermembrane water layers, the coordinates of the center of deuteration of the D11 and D5 label are 10.5 +/- 1.2 and 3.8 +/- 1.5 A, respectively. Alternatively, the label distance may be measured from the nearest membrane surface as defined by the maximum in the neutron scattering length density at the water/membrane interface. With respect to this point, the D11 and D5 labels are located at a depth of 9.9 +/- 1.2 and 16.6 +/- 1.5 A, respectively. The chromophore is tilted with the Schiff base near the middle of the membrane and the ring closer to the membrane surface. The vector connecting the two label positions in the chromophore makes an angle of 40 +/- 12 degrees with the plane of the membrane. Of the two possible orientations of the plane of the chromophore, which is perpendicular to the membrane plane, only the one in which the N----H bond of the Schiff base points toward the same membrane surface as the vector from the Schiff base to the cyclohexene ring is compatible with the known tilt angle of the polyene chain.

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Chromophore of Bacteriorhodopsin is Closer to the Cytoplasmic Surface of Purple Membrane

Cited by 13 publications

References 27 publications

Protein electric response signals from dielectrically polarized systems

Protein electric response signals from dielectrically polarized systems

Orientation of the protonated retinal Schiff base group in bacteriorhodopsin from absorption linear dichroism

Transmembrane location of retinal in bacteriorhodopsin by neutron diffraction

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