Abstract
Energy transfer from light-harvesting carotenoids to chlorophyll is common in photosynthesis, but such antenna pigments have not been observed in retinal-based ion pumps and photoreceptors. Here we describe xanthorhodopsin, a proton-pumping retinal protein/carotenoid complex in the eubacterium Salinibacter ruber. The wavelength dependence of the rate of pumping and difference absorption spectra measured under a variety of conditions indicate that this protein contains two chromophores, retinal and the carotenoid salinixanthin, in a molar ratio of about 1:1. The two chromophores interact strongly, and light energy absorbed by the carotenoid is transferred to the retinal with a quantum efficiency of approximately 40%. The antenna carotenoid extends the wavelength range of the collection of light for uphill transmembrane proton transport.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, Non-P.H.S.
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Amino Acid Sequence
-
Bacteroidetes / chemistry*
-
Bacteroidetes / metabolism
-
Carotenoids / chemistry
-
Carotenoids / metabolism
-
Energy Transfer
-
Glycosides / chemistry
-
Glycosides / metabolism
-
Hydrogen-Ion Concentration
-
Hydroxylamine / pharmacology
-
Light
-
Light-Harvesting Protein Complexes / chemistry*
-
Light-Harvesting Protein Complexes / isolation & purification
-
Light-Harvesting Protein Complexes / metabolism
-
Mass Spectrometry
-
Molecular Sequence Data
-
Oxygen Consumption
-
Proton Pumps / chemistry*
-
Proton Pumps / isolation & purification
-
Proton Pumps / metabolism
-
Retinaldehyde / chemistry
-
Retinaldehyde / metabolism
-
Rhodopsins, Microbial / chemistry*
-
Rhodopsins, Microbial / isolation & purification
-
Rhodopsins, Microbial / metabolism
-
Spectrophotometry, Ultraviolet
-
Spectrum Analysis
Substances
-
Glycosides
-
Light-Harvesting Protein Complexes
-
Proton Pumps
-
Rhodopsins, Microbial
-
salinixanthin
-
Hydroxylamine
-
Carotenoids
-
Retinaldehyde