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Xanthorhodopsin: a proton pump with a light-harvesting carotenoid antenna.

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.

SUBMITTER: Balashov SP

PROVIDER: S-EPMC3065861 | biostudies-literature | 2005 Sep

REPOSITORIES: biostudies-literature

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Xanthorhodopsin: a proton pump with a light-harvesting carotenoid antenna.

Balashov Sergei P SP Imasheva Eleonora S ES Boichenko Vladimir A VA Antón Josefa J Wang Jennifer M JM Lanyi Janos K JK

Science (New York, N.Y.) 20050901 5743

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 a ...[more]

PMID: 16179480

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