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), Journal Name: Biochemistry; (USA) Vol. 28:26; ISSN 0006-2960; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALANINES
AMIDES
AMINES
AMINO ACID SEQUENCE
AMINO ACIDS
AROMATICS
AZAARENES
AZOLES
BACTERIA
BARYONS
CARBOXYLIC ACIDS
CHEMISTRY
ELEMENTARY PARTICLES
ESCHERICHIA COLI
FERMIONS
GLUTAMINE
GLYCINE
HADRONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY ACIDS
INDOLES
INFRARED SPECTRA
LEUCINE
MICROORGANISMS
MOLECULAR STRUCTURE
MUTATIONS
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHENYLALANINE
PHOTOCHEMISTRY
PHOTOSYNTHETIC BACTERIA
PIGMENTS
PROLINE
PROTEINS
PROTONS
PYRROLES
PYRROLIDINES
RHODOPSIN
SERINE
SPECTRA
TRYPTOPHAN