N2-methylation of guanosine at position 10 in tRNA is catalyzed by a THUMP domain-containing, S-adenosylmethionine-dependent methyltransferase, conserved in Archaea and Eukaryota
N2-methylation of guanosine at position 10 in tRNA is catalyzed by a THUMP domain-containing, S-adenosylmethionine-dependent methyltransferase, conserved in Archaea and Eukaryota
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DOI：
10.1074/jbc.m403845200
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发表时间：
2004-08-27
影响因子：
4.8
通讯作者：
Grosjean, H
中科院分区：
文献类型：
--
作者：
Armengaud, J;Urbonavicius, J;Grosjean, H
在已测序的基因组中，属于直链淀粉组COG 1041的基因仅在真核生物和细菌中发现，并且几乎无处不在，但从未在细菌中发现。相应的基因产物在C末端显示出特征性的Rossmann折叠、S-腺苷甲硫氨酸依赖性甲基转移酶结构域和在N末端预测的RNA结合THUMP（（t）在bar hiouridine转移酶下，RNA（m）在bar乙基转移酶下，和（p）在bar hiouridine转移酶下）结构域。重组PAB 1283蛋白从古细菌Pyrococcus abyssi GE 5，一个成员的COG 1041，纯化，表现为一个单体的39-kDa的实体。这种蛋白质（EC 2.1.1.32），现在改名为（Pab）Trm-G10，具有极高的热稳定性，与tRNA形成1：1复合物，并催化位于10位的鸟苷环外氨基（N-2）的腺苷甲硫氨酸依赖性甲基化。根据所使用的实验条件以及所测试的tRNA底物，酶促反应导致N-2-单甲基（m（2）G）或N-2-二甲基鸟苷（m（2）（2）G）的形成。有趣的是，（Pab）Trm-G10表现出与另一种早期表征的来自激烈火球菌的tRNA-二甲基转移酶（（Pfu）Trm-G26，也称为（Pfu）Trm 1，COG 1867的成员）不同的结构域组织和不同的催化位点结构，该转移酶催化鸟苷的相同的两步二甲基化，但在tRNA的26位，并且在所有测序的真核生物和真核生物中也是保守的。这两种鸟苷二甲基转移酶在真核生物和真核生物中同时存在，但在细菌中不存在，这是这些生命结构域之间不同的tRNA成熟策略的标志。
In sequenced genomes, genes belonging to the cluster of orthologous group COG1041 are exclusively, and almost ubiquitously, found in Eukaryota and Archaea but never in Bacteria. The corresponding gene products exhibit a characteristic Rossmann fold, S-adenosyl-methionine-dependent methyltransferase domain in the C terminus and a predicted RNA-binding THUMP ((t) under bar hiouridine synthases, RNA (m) under bar ethyltransferases, and (p) under bar seudouridine synthases) domain in the N terminus. Recombinant PAB1283 protein from the archaeon Pyrococcus abyssi GE5, a member of COG1041, was purified and shown to behave as a monomeric 39-kDa entity. This protein (EC 2.1.1.32), now renamed (Pab)Trm-G10, which is extremely thermostable, forms a 1:1 complex with tRNA and catalyzes the adenosylmethionine-dependent methylation of the exocyclic amino group (N-2) of guanosine located at position 10. Depending on the experimental conditions used, as well as the tRNA substrate tested, the enzymatic reaction leads to the formation of either N-2-monomethyl (m(2)G) or N-2-dimethylguanosine (m(2)(2)G). Interestingly, (Pab)Trm-G10 exhibits different domain organization and different catalytic site architecture from another, earlier characterized, tRNA-dimethyltransferase from Pyrococcus furiosus ((Pfu)Trm-G26, also known as (Pfu)Trm1, a member of COG1867) that catalyzes an identical two-step dimethylation of guanosine but at position 26 in tRNAs and is also conserved among all sequenced Eukaryota and Archaea. The co-occurrence of these two guanosine dimethyltransferases in both Archaea and Eukaryota but not in Bacteria is a hallmark of distinct tRNAs maturation strategies between these domains of life.