Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments

作者：Davies Wayne I L; Wilkie Susan E; Cowing Jill A; Hankins Mark W; Hunt David M^*

来源：Cellular and Molecular Life Sciences, 2012, 69(14): 2455-2464.

DOI：10.1007/s00018-012-0934-4

• Visual pigments
• Mouse
• Colour vision
• Spectral tuning
• Anion sensitivity

The long-wavelength-sensitive (LWS) opsins form one of four classes of vertebrate cone visual pigment and exhibit peak spectral sensitivities (lambda(max)) that generally range from 525 to 560 nm for rhodopsin/vitamin-A(1) photopigments. Unique amongst the opsin classes, many LWS pigments show anion sensitivity through the interaction of chloride ions with a histidine residue at site 197 (H197) to give a long-wavelength spectral shift in peak sensitivity. Although it has been shown that amino acid substitutions at five sites (180, 197, 277, 285 and 308) are useful in predicting the lambda(max) values of the LWS pigment class, some species, such as the elephant shark and most marine mammals, express LWS opsins that possess lambda(max) values that are not consistent with this %26apos;five-site%26apos; rule, indicating that other interactions may be involved. This study has taken advantage of the natural mutation at the chloride-binding site in the mouse LWS pigment. Through the use of a number of mutant pigments generated by site-directed mutagenesis, a new model has been formulated that takes into account the role of charge and steric properties of the side chains of residues at sites 197 and 308 in the function of the chloride-binding site in determining the peak sensitivity of LWS photopigments.

• 出版日期2012-7