Vinogradov Serge N, Hoogewijs David, Bailly Xavier, Arredondo-Peter Raúl, Guertin Michel, Gough Julian, Dewilde Sylvia, Moens Luc, Vanfleteren Jacques R
Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Proc Natl Acad Sci U S A. 2005 Aug 9;102(32):11385-9. doi: 10.1073/pnas.0502103102. Epub 2005 Aug 1.
Although most globins, including the N-terminal domains within chimeric proteins such as flavohemoglobins and globin-coupled sensors, exhibit a 3/3 helical sandwich structure, many bacterial, plant, and ciliate globins have a 2/2 helical sandwich structure. We carried out a comprehensive survey of globins in the genomes from the three kingdoms of life. Bayesian phylogenetic trees based on manually aligned sequences indicate the possibility of past horizontal globin gene transfers from bacteria to eukaryotes. blastp searches revealed the presence of 3/3 single-domain globins related to the globin domains of the bacterial and fungal flavohemoglobins in many bacteria, a red alga, and a diatom. Iterated psi-blast searches based on groups of globin sequences found that only the single-domain globins and flavohemoglobins recognize the eukaryote 3/3 globins, including vertebrate neuroglobins, alpha- and beta-globins, and cytoglobins. The 2/2 globins recognize the flavohemoglobins, as do the globin coupled sensors and the closely related single-domain protoglobins. However, the 2/2 globins and the globin-coupled sensors do not recognize each other. Thus, all globins appear to be distributed among three lineages: (i) the 3/3 plant and metazoan globins, single-domain globins, and flavohemoglobins; (ii) the bacterial 3/3 globin-coupled sensors and protoglobins; and (iii) the bacterial, plant, and ciliate 2/2 globins. The three lineages may have evolved from an ancestral 3/3 or 2/2 globin. Furthermore, it appears likely that the predominant functions of globins are enzymatic and that oxygen transport is a specialized development that accompanied the evolution of metazoans.
尽管大多数珠蛋白，包括嵌合蛋白（如黄素血红蛋白和珠蛋白偶联传感器）中的N端结构域，都呈现出3/3螺旋三明治结构，但许多细菌、植物和纤毛虫珠蛋白具有2/2螺旋三明治结构。我们对来自生命三界基因组中的珠蛋白进行了全面调查。基于手动比对序列构建的贝叶斯系统发育树表明，过去存在细菌向真核生物水平转移珠蛋白基因的可能性。blastp搜索显示，在许多细菌、一种红藻和一种硅藻中存在与细菌和真菌黄素血红蛋白的珠蛋白结构域相关的3/3单结构域珠蛋白。基于珠蛋白序列组进行的迭代psi-blast搜索发现，只有单结构域珠蛋白和黄素血红蛋白能够识别真核生物的3/3珠蛋白，包括脊椎动物神经珠蛋白、α-和β-珠蛋白以及细胞珠蛋白。2/2珠蛋白能够识别黄素血红蛋白，珠蛋白偶联传感器和与之密切相关的单结构域原珠蛋白也能识别。然而，2/2珠蛋白和珠蛋白偶联传感器彼此不能识别。因此，所有珠蛋白似乎分布在三个谱系中：（i）3/3植物和后生动物珠蛋白、单结构域珠蛋白和黄素血红蛋白；（ii）细菌的3/3珠蛋白偶联传感器和原珠蛋白；（iii）细菌、植物和纤毛虫的2/2珠蛋白。这三个谱系可能从一个祖先的3/3或2/2珠蛋白进化而来。此外，珠蛋白的主要功能似乎是酶促作用，而氧运输是后生动物进化过程中伴随出现的一种特殊发展。
