Deprotonation of tyrosines in bacteriorhodopsin as studied by Fourier transform infrared spectroscopy with deuterium and nitrate labeling

Lin, Shuo; Ormos, Pál; Eisenstein, L.; Govindjee, Rajni; Konno, Katsuhiro; Nakanishi, Koji

doi:10.1021/bi00399a045

Cited by 20 publications

(8 citation statements)

References 27 publications

(51 reference statements)

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“…Asp-212 ion pair. Low temperature FTIR experiments have argued that Tyr-185 is ionized in BR568 (Lin et al, 1987;Roepe et al, 1987;Braiman et al, 1988b). However, this prediction is in disagreement with recent solidstate '3C-nuclear magnetic resonance results (Griffin et al, 1989).…”

Section: Structural Model For Bacteriorhodopsinmentioning

confidence: 87%

“…Subsequent prote,in relaxation and the deprotonation of the Schiff base lead to the formation of M412 and the release of protons to the external medium. Fourier transform infrared (FTIR) studies have assigned changes in the protonation states of nearby tyrosine (Lin et al, 1987;Roepe et al, 1987;Braiman et al, 1988b) and aspartate residues (Engelhard et al, 1985;Eisenstein et al, 1987;Braiman et al, 1988a) in the photocycle. These observations provide evidence for interactions between the Schiff base and protein residues, which play a critical role in the mechanism of the proton pump.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Structural Model For Bacteriorhodopsinmentioning

confidence: 87%

Section: Introductionmentioning

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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“…The proton transport occurs through protonable groups; aspartic and tyrosine residues have been shown to be members of the proton transport chain by Fourier transform infrared (FTIR) difference spectroscopy (4)(5)(6)(7)(8)(9).…”

Section: Br-k-l-m-n-o-brmentioning

confidence: 99%

Infrared spectroscopic demonstration of a conformational change in bacteriorhodopsin involved in proton pumping.

Ormos

1991

Proc. Natl. Acad. Sci. U.S.A.

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Infrared spectral changes in bacteriorhodopsin (bR) were followed during the slow decay of the M intermediate in the temperature region 240-260 K. The decay of the M form is characterized by the disappearance of the ethylenic bands and the bands indicating the reprotonation of the Schiff base. The route of Schiff-base reprotonation completely changes between 240 K and 260 K. At 240 K reprotonation occurs from Asp-85, the group to which the proton was released during M formation, and there is no pumping. At 260 K Schiff-base reprotonation takes place through Asp-96 from the cytoplasmic side, in the normal sequence assumed for proton pumping. The dramatic change in the route of Schiffbase reprotonation is coupled to a protein conformational change characterized by the change of the ratio of the two amide I bands at 1658 cm-' and 1669 cm-'. This conformational change is interpreted as the conformational switch crucial for proton pumping: a protein relaxation following M formation results in a local rearrangement of the group, in the vicinity of the Schiff base. The rearrangement changes the accessibility of the Schiff base and provides that its deprotonation and reprotonation occur on different sides. The conformational change has characteristics typical for relaxations in proteins. In addition, it is shown that at 260 K an equilibrium exists between the M and N forms.

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“…The role of tyrosine in the bacteriorhodopsin photocycle has been the subject of several recent FTIR studies (Rothschild et al, 1986a;Dollinger et al, 1986a;Roepe et al, 1987a,b;Lin et al, 1987). In these studies, labelled tyrosine is incorporated into bacteriorhodopsin by growing Halobacteria halobium on a stringent synthetic medium containing the labelled tyrosine.…”

Section: Detection Of Tyrosine Protonation Changes During the Br Photmentioning

confidence: 99%

Infrared Studies of Bacteriorhodopsin

Rothschild

1988

Photochem & Photobiology

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Deprotonation of tyrosines in bacteriorhodopsin as studied by Fourier transform infrared spectroscopy with deuterium and nitrate labeling

Cited by 20 publications

References 27 publications

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

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

Infrared spectroscopic demonstration of a conformational change in bacteriorhodopsin involved in proton pumping.

Infrared Studies of Bacteriorhodopsin

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