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Fourier-transform infrared difference spectroscopy has been used to study the role of the three membrane-embedded proline residues, Pro-50, Pro-91, and Pro-186, in the structure and function of bacteriorhodopsin. All three prolines were replaced by alanine and glycine; in addition, Pro-186 was changed to valine. Difference spectra were recorded for the bR----K and bR----M photoreactions of each of these mutants and compared to those of wild-type bacteriorhodopsin. Only substitutions of Pro-186 caused significant perturbations in the frequency of the C = C and C - C stretching modes of the retinylidene chromophore. In addition, these substitutions reduced bands in the amide I and II region associated with secondary structural changes and altered signals assigned to the adjacent Tyr-185. Pro-186----Val caused the largest alterations, producing a second species similar to bR548 and nearly blocking chromophore isomerization at 78 K but not at 250 K. These results are consistent with a model of the retinal binding site in which Pro-186 and Tyr-185 are located in direct proximity to the chromophore and may be involved in linking chromophore isomerization to protein structural changes. Evidence is also found that Pro-50 may be structurally active during the bR----K transition and that substitution of this residue by glycine preserves the normal protein structural changes during the photocycle.
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
August 1989,
Biochemistry,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
January 1991,
Biochimica et biophysica acta,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
July 1985,
Bioscience reports,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
August 2002,
Science (New York, N.Y.),
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
January 1988,
Proteins,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
October 2006,
The journal of physical chemistry. B,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
January 1985,
The Journal of membrane biology,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
October 1991,
The Journal of biological chemistry,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
October 1978,
Biophysical journal,
K J Rothschild, and
Y W He, and
T Mogi, and
T Marti, and
L J Stern, and
H G Khorana
September 1991,
The EMBO journal,
