Alieva Naila O, Konzen Karen A, Field Steven F, Meleshkevitch Ella A, Hunt Marguerite E, Beltran-Ramirez Victor, Miller David J, Wiedenmann Jörg, Salih Anya, Matz Mikhail V
Section of Integrative Biology, University of Texas at Austin, Austin, Texas, United States of America.
PLoS One. 2008 Jul 16;3(7):e2680. doi: 10.1371/journal.pone.0002680.
GFP-like fluorescent proteins (FPs) are the key color determinants in reef-building corals (class Anthozoa, order Scleractinia) and are of considerable interest as potential genetically encoded fluorescent labels. Here we report 40 additional members of the GFP family from corals. There are three major paralogous lineages of coral FPs. One of them is retained in all sampled coral families and is responsible for the non-fluorescent purple-blue color, while each of the other two evolved a full complement of typical coral fluorescent colors (cyan, green, and red) and underwent sorting between coral groups. Among the newly cloned proteins are a "chromo-red" color type from Echinopora forskaliana (family Faviidae) and pink chromoprotein from Stylophora pistillata (Pocilloporidae), both evolving independently from the rest of coral chromoproteins. There are several cyan FPs that possess a novel kind of excitation spectrum indicating a neutral chromophore ground state, for which the residue E167 is responsible (numeration according to GFP from A. victoria). The chromoprotein from Acropora millepora is an unusual blue instead of purple, which is due to two mutations: S64C and S183T. We applied a novel probabilistic sampling approach to recreate the common ancestor of all coral FPs as well as the more derived common ancestor of three main fluorescent colors of the Faviina suborder. Both proteins were green such as found elsewhere outside class Anthozoa. Interestingly, a substantial fraction of the all-coral ancestral protein had a chromohore apparently locked in a non-fluorescent neutral state, which may reflect the transitional stage that enabled rapid color diversification early in the history of coral FPs. Our results highlight the extent of convergent or parallel evolution of the color diversity in corals, provide the foundation for experimental studies of evolutionary processes that led to color diversification, and enable a comparative analysis of structural determinants of different colors.
绿色荧光蛋白样荧光蛋白（FPs）是造礁珊瑚（珊瑚虫纲，石珊瑚目）中关键的颜色决定因素，作为潜在的基因编码荧光标记备受关注。在此，我们报告了来自珊瑚的另外40个绿色荧光蛋白家族成员。珊瑚荧光蛋白有三个主要的旁系同源谱系。其中一个在所有采样的珊瑚家族中都有保留，负责非荧光的紫蓝色，而另外两个谱系中的每一个都进化出了完整的典型珊瑚荧光颜色（青色、绿色和红色），并在珊瑚群体之间进行了分类。新克隆的蛋白质中有来自福氏棘孔珊瑚（蜂巢珊瑚科）的“铬红”颜色类型和来自细指鹿角珊瑚（鹿角珊瑚科）的粉色荧光蛋白，它们都是从其他珊瑚荧光蛋白中独立进化而来的。有几种青色荧光蛋白具有一种新型的激发光谱，表明发色团处于中性基态，这是由残基E167（根据维多利亚多管水母的绿色荧光蛋白编号）负责的。多孔鹿角珊瑚的荧光蛋白是一种不寻常的蓝色而不是紫色，这是由于两个突变：S64C和S183T。我们应用了一种新的概率抽样方法来重建所有珊瑚荧光蛋白的共同祖先以及法维拉纳亚目三种主要荧光颜色的更为衍生的共同祖先。这两种蛋白质都是绿色的，就像在珊瑚虫纲以外的其他地方发现的那样。有趣的是，所有珊瑚祖先蛋白的很大一部分都有一个显然锁定在非荧光中性状态的发色团，这可能反映了一个过渡阶段，该阶段使得在珊瑚荧光蛋白历史早期能够快速实现颜色多样化。我们的结果突出了珊瑚颜色多样性趋同或平行进化的程度，为导致颜色多样化的进化过程的实验研究提供了基础，并能够对不同颜色的结构决定因素进行比较分析。
