Queuosine Formation in Eukaryotic tRNA Occurs via a Mitochondria-localized Heteromeric Transglycosylase
Queuosine Formation in Eukaryotic tRNA Occurs via a Mitochondria-localized Heteromeric Transglycosylase
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DOI：
10.1074/jbc.m109.002477
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发表时间：
2009-07-03
影响因子：
4.8
通讯作者：
Kelly, Vincent P.
中科院分区：
文献类型：
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作者：
Boland, Coilin;Hayes, Patti;Kelly, Vincent P.
tRNA鸟嘌呤转糖基酶（TGT）负责在tRNAAsp、tRNAAsn、tRNAHis和tRNATyr的反密码子环（位置34）中形成肌苷;这是真细菌和真核生物物种中几乎普遍存在的事件。尽管对真细菌TGT进行了广泛的表征，但真核生物的活性仍然不确定。我们的小鼠EST和cDNA数据库的搜索确定了同源的大肠杆菌TGT和三个剪接的变异体的鸟嘌呤tRNA鸟嘌呤转糖基酶结构域包含1（QTRTD 1）基因。发现QTRTD 1变体_1（Qv 1）是主要的成虫形式。通过北方印迹中TGT和Qv 1的协调mRNA表达以及通过免疫沉淀法从它们在体内的关联表明TGT和Qv 1的功能协同性。TGT和Qv 1都不能单独补充E.杆菌然而，当蛋白质在体外结合时，可以获得转糖基酶活性。共聚焦和免疫印迹分析表明，TGT弱相互作用与线粒体外膜可能通过协会与Qv 1，这被认为是稳定相关的细胞器。
tRNA guanine transglycosylase (TGT) enzymes are responsible for the formation of queuosine in the anticodon loop ( position 34) of tRNAAsp, tRNAAsn, tRNAHis, and tRNATyr; an almost universal event in eubacterial and eukaryotic species. Despite extensive characterization of the eubacterial TGT the eukaryotic activity has remained undefined. Our search of mouse EST and cDNA data bases identified a homologue of the Escherichia coli TGT and three spliced variants of the queuine tRNA guanine transglycosylase domain containing 1 (QTRTD1) gene. QTRTD1 variant_1 (Qv1) was found to be the predominant adult form. Functional cooperativity of TGT and Qv1 was suggested by their coordinate mRNA expression in Northern blots and from their association in vivo by immunoprecipitation. Neither TGT nor Qv1 alone could complement a tgt mutation in E. coli. However, transglycosylase activity could be obtained when the proteins were combined in vitro. Confocal and immunoblot analysis suggest that TGT weakly interacts with the outer mitochondrial membrane possibly through association with Qv1, which was found to be stably associated with the organelle.