Unique phylogenetic relationships of glucokinase and glucosephosphate isomerase of the amitochondriate eukaryotes Giardia intestinalis, Spironucleus barkhanus and Trichomonas vaginalis
Unique phylogenetic relationships of glucokinase and glucosephosphate isomerase of the amitochondriate eukaryotes Giardia intestinalis, Spironucleus barkhanus and Trichomonas vaginalis
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DOI：
10.1016/s0378-1119(01)00773-9
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发表时间：
2001-12-27
期刊：
影响因子：
3.5
通讯作者：
Embley, TM
中科院分区：
文献类型：
--
作者：
Henze, K;Horner, DS;Embley, TM
本文报道了Ⅰ型无线粒体真核生物贾第鞭毛虫和巴氏螺旋核菌糖酵解途径前两个酶葡萄糖激酶（GK）和葡萄糖磷酸异构酶（GPI）的基因序列。还测定了迷走毛滴虫的GPI。单胞菌GK属于存在于蓝细菌、某些变形菌以及T. vagelis，E型无线粒体原生生物。这些酶不是己糖激酶家族的一部分，己糖激酶家族广泛分布于真核生物中，包括I型无线粒体寄生虫溶组织内阿米巴。G.在大肠杆菌中表达的葡聚糖激酶对葡萄糖和葡聚糖具有特异性，其真细菌同源物也是如此。单胞菌和滴虫的GPIs序列形成了一个单系群，与蓝藻和叶绿体序列的关系比与其他真核生物和原核生物的胞质GPIs的关系更密切。这些发现表明，这些无线粒体原生生物的能量代谢的某些酶的来源不同于其他真核生物。观察到这两种昆虫和T.迷走神经元具有相同的不寻常GK和GPI，这与基因树相一致，表明在嗜热单胞菌和副嗜热单胞菌之间存在密切的关系。这些酶的蓝藻（和叶绿体）酶的有趣的关系可能反映了水平的基因转移之间的共同祖先的藻类和parabasalid谱系和蓝藻的祖先。(C)2001 Elsevier Science B.V.保留所有权利。
Glucokinase (GK) and glucosephosphate isomerase (GPI), the first two enzymes of the glycolytic pathway of the diplomonads Giardia intestinalis and Spironucleus barkhanus, Type I amitochondriate eukaryotes, were sequenced. GPI of the parabasalid Trichomonas vaginalis was also sequenced. The diplomonad GKs belong to a family of specific GKs present in cyanobacteria, in some proteobacteria and also in T. vaginalis, a Type E amitochondriate protist. These enzymes are not part of the hexokinase family, which is broadly distributed among eukaryotes, including the Type I amitochondriate parasite Entamoeba histolytica. G. intestinalis GK expressed in Escherichia coli was specific for glucose and glucosan-tine, as are its eubacterial homologs. The sequence of diplomonad and trichomonad GPIs formed a monophyletic group more closely related to cyanobacterial and chloroplast sequences than to cytosolic GPIs of other eukaryotes and prokaryotes. The findings show that certain enzymes of the energy metabolism of these amitochondriate protists originated from sources different than those of other eukaryotes. The observation that the two diplomonads and T. vaginalis share the same unusual GK and GPI is consistent with gene trees that suggest a close relationship between diplomonads and parabasalids. The intriguing relationships of these enzymes to cyanobacterial (and chloroplast) enzymes might reflect horizontal gene transfer between the common ancestor of the diplomonad and parabasalid lineages and the ancestor of cyanobacteria. (C) 2001 Elsevier Science B.V. All rights reserved.