Phylogenetic relationships of non-mitochondrial nucleotide transport proteins in bacteria and eukaryotes
Phylogenetic relationships of non-mitochondrial nucleotide transport proteins in bacteria and eukaryotes
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DOI：
10.1016/s0378-1119(03)00429-3
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发表时间：
2003-03-13
期刊：
影响因子：
3.5
通讯作者：
Neuhaus, HE
中科院分区：
文献类型：
--
作者：
Linka, N;Hurka, H;Neuhaus, HE
目前关于细胞内细菌核苷酸代谢的知识非常有限。在这里，我们报告的鉴定核苷酸转运蛋白（NTT）的两个专性内寄生虫，Caedibacter caryophila和Holospora obtusa，α-变形菌，这驻留在草履虫的营养大核。为了进行比较研究，我们还确定了第一个核苷酸转运蛋白的叶绿体中的一个红色的，即Galdieria sulphuraria，并进一步同源植物叶绿体。异源表达C. caryophila，H. obtusa和G. sulphuraria在大肠杆菌中的表达表明，由这些转运蛋白介导的核苷酸内流对ATP和ADP具有特异性。C. caryophila和H. obtusa与它们在人类叶绿体和细胞内细菌病原体中的对应物表现出实质上的序列同一性，但与线粒体的核苷酸转运系统不具有序列同一性。对细菌和叶绿体NTT蛋白的系统发育分析表明，植物、绿色、红藻、绿藻和蓝囊藻叶绿体中的NTT蛋白同源物是单系的。相比之下，细菌对应物的进化关系似乎非常复杂。在本研究中，C. caryophila和H. obtusa只是远缘关系，虽然这两个分类群在16 S rRNA树中是近亲。树状拓扑结构表明，一些细菌NTT旁系同源物已经出现的基因复制和其他水平转移。(C)2003 Elsevier Science B. V.保留所有权利。
Current knowledge about the nucleotide metabolism of intracellular bacteria is very limited. Here we report on the identification of nucleotide transport proteins (NTT) of two obligate endoparasites, Caedibacter caryophila and Holospora obtusa, both alpha-proteobacteria, which reside in the vegetative macronucleus of Paramecium caudatum. For comparative studies, we also identified the first nucleotide transporter in chloroplasts of a red alga, i.e. Galdieria sulphuraria, and further homologs in plant chloroplasts. Heterologous expression of the NTT proteins from C. caryophila, H. obtusa, and G. sulphuraria in Escherichia coli demonstrate that the nucleotide influx mediated by these transporters is specific for ATP and ADP. The NTT proteins of C. caryophila and H. obtusa exhibit substantial sequence identity with their counterparts in chloroplasts and intracellular bacterial pathogens of humans, but not with the nucleotide transport system of mitochondria. Comprehensive phylogenetic analyses of bacterial and chloroplast NTT proteins showed that homologs in chloroplasts from plants, and green, red, stramenopile and glaucocystophyte algae are monophyletic. In contrast, the evolutionary relationships of the bacterial counterparts appear highly complex. In the presented phylogeny, NTT proteins of C. caryophila and H. obtusa are only distantly related to one another, although these two taxa are close relatives in 16S rRNA trees. The tree topology indicates that some bacterial NTT paralogs have arisen by gene duplications and others by horizontal transfer. (C) 2003 Elsevier Science B.V. All rights reserved.