Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments
Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments
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DOI：
10.1007/s00018-012-0934-4
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发表时间：
2012-07-01
影响因子：
8
通讯作者：
Hunt, David M.
中科院分区：
文献类型：
--
作者：
Davies, Wayne I. L.;Wilkie, Susan E.;Hunt, David M.
长波长敏感（LWS）视蛋白形成四类脊椎动物视锥细胞色素之一，并且对于视紫红质/维生素A（1）色素显示出通常在525至560 nm范围内的峰值光谱敏感性（λ（max））。在视蛋白类中是独特的，许多LWS色素通过氯离子与位点197（H197）处的组氨酸残基的相互作用显示阴离子敏感性，以在峰值敏感性中产生长波长光谱偏移。虽然已经表明，在五个位点的氨基酸取代，（180，197，277，285和308）在预测LWS色素类的λ（max）值中是有用的，一些物种，例如象鲨和大多数海洋哺乳动物，表达具有与该“五位点”规则不一致的λ（max）值的LWS视蛋白，这表明可能涉及其他相互作用。本研究利用了小鼠LWS色素中氯结合位点的自然突变。通过使用的一些突变体的色素产生的定点诱变，一个新的模型已制定考虑到的作用，电荷和空间位阻性质的残基侧链在网站197和308中的氯离子结合位点的功能，在确定的峰值灵敏度的LWS色素。
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 'five-site' 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.