Relocating the active-site lysine in rhodopsin and implications for evolution of retinylidene proteins
Relocating the active-site lysine in rhodopsin and implications for evolution of retinylidene proteins
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DOI：
10.1073/pnas.1306826110
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发表时间：
2013-08-13
影响因子：
11.1
通讯作者：
Theobald, Douglas L.
中科院分区：
文献类型：
--
作者：
Devine, Erin L.;Oprian, Daniel D.;Theobald, Douglas L.
I型和II型视紫红质具有几个结构特征，包括G蛋白偶联受体折叠和在蛋白质的第7跨膜段高度保守的活性位点赖氨酸残基。然而，这两个家族缺乏显着的序列相似性，这将表明共同的祖先。因此，视紫质折叠和保守的赖氨酸被广泛认为是在趋同进化过程中由于功能限制而产生的。为了测试这种约束的存在，我们询问是否有可能在视觉色素牛视紫红质中重新定位高度保守的Lys296。我们在这里表明，Lys可以移动到蛋白质中的其他三个位置，同时保持与11-顺式视网膜形成色素的能力，并以光依赖的方式激活G蛋白转导蛋白。这些结果反驳了趋同假说，支持I型和II型视紫红质从一个共同的祖先蛋白发散进化而来的同源性。
Type I and type II rhodopsins share several structural features including a G protein-coupled receptor fold and a highly conserved active-site Lys residue in the seventh transmembrane segment of the protein. However, the two families lack significant sequence similarity that would indicate common ancestry. Consequently, the rhodopsin fold and conserved Lys are widely thought to have arisen from functional constraints during convergent evolution. To test for the existence of such a constraint, we asked whether it were possible to relocate the highly conserved Lys296 in the visual pigment bovine rhodopsin. We show here that the Lys can be moved to three other locations in the protein while maintaining the ability to form a pigment with 11-cis-retinal and activate the G protein transducin in a light-dependent manner. These results contradict the convergent hypothesis and support the homology of type I and type II rhodopsins by divergent evolution from a common ancestral protein.