Originally published as Genetics Published Articles Ahead of Print on July 27, 2008.

Genetics, Vol. 179, 2037-2043, August 2008, Copyright © 2008
doi:10.1534/genetics.108.090449

Molecular Basis of Spectral Tuning in the Red- and Green-Sensitive (M/LWS) Pigments in Vertebrates

Shozo Yokoyama*,1, Hui Yang* and William T. Starmer{dagger}

* Department of Biology, Emory University, Atlanta, Georgia 30322 and {dagger} Department of Biology, Syracuse University, Syracuse, New York 13244

1 Corresponding author: Department of Biology, Rollins Research Center, Emory University, 1510 Clifton Rd., Atlanta, GA 30322.
E-mail: syokoya{at}emory.edu

Vertebrate vision is mediated by five groups of visual pigments, each absorbing a specific wavelength of light between ultraviolet and red. Despite extensive mutagenesis analyses, the mechanisms by which contemporary pigments absorb variable wavelengths of light are poorly understood. We show that the molecular basis of the spectral tuning of contemporary visual pigments can be illuminated only by mutagenesis analyses using ancestral pigments. Following this new principle, we derive the "five-sites" rule that explains the absorption spectra of red and green (M/LWS) pigments that range from 510 to 560 nm. Our findings demonstrate that the evolutionary method should be used in elucidating the mechanisms of spectral tuning of four other pigment groups and, for that matter, functional differentiations of any other proteins.


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Genetics 2008 179: NP. [Full Text]