Molecular basis of spectral tuning in the red- and green-sensitive (M/LWS) pigments in vertebrates.

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.

脊椎动物的视觉由五类视觉色素介导，每类色素吸收紫外线到红光之间特定波长的光。尽管已开展大量诱变分析，但对于现代色素吸收不同波长光的机制，人们仍知之甚少。我们发现，只有通过对祖先色素进行诱变分析，才能阐明现代视觉色素光谱调谐的分子基础。遵循这一新原则，我们得出了 “五位点” 规则，该规则可解释吸收光谱在510至560纳米之间的红色和绿色（中/长波敏感，M/LWS）色素的情况。我们的研究结果表明，在阐释其他四类色素的光谱调谐机制，乃至任何其他蛋白质的功能分化机制时，都应采用进化分析方法。