Somatic cancer mutations in the DNMT2 tRNA methyltransferase alter its catalytic properties
Somatic cancer mutations in the DNMT2 tRNA methyltransferase alter its catalytic properties
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DOI：
10.1016/j.biochi.2015.02.022
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发表时间：
2015-05-01
期刊：
影响因子：
3.9
通讯作者：
Jeltsch, Albert
中科院分区：
文献类型：
--
作者：
Elhardt, Winfried;Shanmugam, Raghuvaran;Jeltsch, Albert
tRNA的甲基化是一种重要的转录后修饰，tRNA修饰中的异常与癌症有关。DNMT 2蛋白甲基化tRNA-Asp的C38，并且其在细胞生理学和应激反应中具有作用，并且其表达水平在癌组织中改变。在这里，我们研究了在癌组织中发现的DNMT 2体细胞突变是否会影响该酶的活性。我们已经产生了13个DNMT 2变体，并纯化了相应的蛋白质。通过圆二色谱法测定，所有蛋白质均正确折叠。我们使用体外产生的tRNA-Asp测试了它们的RNA甲基化活性。其中一个突变（E63 K）导致活性增加两倍，而其中两个突变导致活性强烈（超过四倍）降低（G155 S和L257 V）。另外两个突变蛋白几乎是无活性的（R371 H和G155 V）。一些体细胞癌突变对DNMT 2活性的强烈影响表明这些突变在肿瘤发生中具有功能性作用。(C)2015 Elsevier B. V.和法国生物化学与生物分子学会（SFBBM）。All rights reserved.
Methylation of tRNA is an important post-transcriptional modification and aberrations in tRNA modification has been implicated in cancer. The DNMT2 protein methylates C38 of tRNA-Asp and it has a role in cellular physiology and stress response and its expression levels are altered in cancer tissues. Here we studied whether DNMT2 somatic mutations found in cancer tissues affect the activity of the enzyme. We have generated 13 DNMT2 variants and purified the corresponding proteins. All proteins were properly folded as determined by circular dichroism spectroscopy. We tested their RNA methylation activity using in vitro generated tRNA-Asp. One of the mutations (E63K) caused a twofold increase in activity, while two of them led to a strong (over fourfold) decrease in activity (G155S and L257V). Two additional mutant proteins were almost inactive (R371H and G155V). The strong effect of some of the somatic cancer mutations on DNMT2 activity suggests that these mutations have a functional role in tumorigenesis. (C) 2015 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM). All rights reserved.