Spectral tuning in the mammalian short-wavelength sensitive cone pigments
Spectral tuning in the mammalian short-wavelength sensitive cone pigments
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DOI：
10.1021/bi0200413
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发表时间：
2002-05-28
期刊：
影响因子：
2.9
通讯作者：
Oprian, DD
中科院分区：
文献类型：
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作者：
Fasick, JI;Applebury, ML;Oprian, DD
野生型小鼠紫外线(UV)和牛蓝视锥视觉色素的最大吸收波长分别为358和438 nm，氨基酸同源性为87%。为了确定这些色素之间80 nm光谱漂移的分子基础，我们选择了螺旋II和III中的几个氨基酸进行定点突变。这些氨基酸包括：(1)那些与小鼠紫外线和牛蓝不同的氨基酸；(2)保守的反离子Glu113；以及(3)Ser90，它参与了鸟类短波灵敏锥体色素的波长调制。这些研究的结果是确定了86位的单一氨基酸取代，导致了小鼠紫外光和牛蓝锥体色素之间的大部分光谱位移。这是这种氨基酸本身第一次被证明在SWS1锥体颜料的光谱调谐中发挥主要作用。单一氨基酸取代似乎是大多数哺乳动物短波敏锥色素将其最大吸收峰从紫外区转移到可见光区的主要因素。研究保守的反离子Glu 113的作用表明，牛和小鼠的SWS1色素分别来自质子化和非质子化的Schiff碱发色团。
The wild-type mouse ultraviolet (UV) and bovine blue cone visual pigments have absorption maxima of 358 and 438 nm, respectively, while sharing 87% amino acid identity. To determine the molecular basis underlying the 80 nm spectral shift between these pigments, we selected several amino acids in helices II and III for site-directed mutagenesis. These amino acids included: (1) those that differ between mouse UV and bovine blue; (2) the conserved counterion, Glu113; and (3) Ser90, which is involved in wavelength modulation in avian short-wavelength sensitive cone pigments. These studies resulted in the identification of a single amino acid substitution at position 86 responsible for the majority of the spectral shift between the mouse UV and bovine blue cone pigments. This is the first time that this amino acid by itself has been shown to play a major role in the spectral tuning of the SWS1 cone pigments. A single amino acid substitution appears to be the dominant factor by which the majority of mammalian short-wavelength sensitive cone pigments have shifted their absorption maxima from the UV to the visible regions of the spectrum. Studies investigating the role of the conserved counterion Glu 113 suggest that the bovine and mouse SWS1 pigments result from a protonated and unprotonated Schiff base chromophore, respectively.