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Science. 2005 Sep 23;309(5743):2061-4.

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

Author information

1
University of California, Irvine, CA 92697, USA. balashov@uci.edu

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.

PMID:
16179480
PMCID:
PMC3065861
DOI:
10.1126/science.1118046
[Indexed for MEDLINE]
Free PMC Article

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