Substitution of amino acids in helix F of bacteriorhodopsin: Effects on the photochemical cycle
- Boston Univ., MA (USA)
The effects of amino acid substitutions in helix F of bacteriorhodopsin on the photocycle of this light-driven proton pump were studied. The photocycles of Ser-183----Ala and Glu-194----Gln mutants were qualitatively similar to that of wild-type bacteriorhodopsin produced in Escherichia coli and bacteriorhodopsin from Halobacterium halobium. The substitution of a Phe for either Trp-182 or Trp-189 significantly reduced the fraction of photocycling bacteriorhodopsin. The amino acid substitutions Tyr-185----Phe and Ser-193----Ala substantially increased the lifetime of the photocycle without substantially increasing the lifetime of the M photocycle intermediate. Similar results were also obtained with the Pro-186----Gly substitution. In contrast, replacing Pro-186 with the larger residue Leu inhibited the formation of the M photocycle intermediate. These results are consistent with a structural model of the retinal-binding pocket suggested by low-temperature UV/visible and Fourier transform infrared difference spectroscopies that has Trp-182, Tyr-185, Pro-186, and Trp-189 forming part of the binding pocket.
- OSTI ID:
- 6945909
- Journal Information:
- Biochemistry; (USA), Vol. 28:26; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RHODOPSIN
MOLECULAR STRUCTURE
ALANINES
AMINO ACID SEQUENCE
AMINO ACIDS
ESCHERICHIA COLI
GLUTAMINE
GLYCINE
INFRARED SPECTRA
LEUCINE
MUTATIONS
PHENYLALANINE
PHOTOCHEMISTRY
PHOTOSYNTHETIC BACTERIA
PROLINE
PROTONS
SERINE
TRYPTOPHAN
AMIDES
AMINES
AROMATICS
AZAARENES
AZOLES
BACTERIA
BARYONS
CARBOXYLIC ACIDS
CHEMISTRY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY ACIDS
INDOLES
MICROORGANISMS
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
PYRROLES
PYRROLIDINES
SPECTRA
550200* - Biochemistry