RimO, a MiaB-like enzyme, methylthiolates the universally conserved Asp88 residue of ribosomal protein S12 in Escherichia coli
RimO, a MiaB-like enzyme, methylthiolates the universally conserved Asp88 residue of ribosomal protein S12 in Escherichia coli
复制标题
DOI：
10.1073/pnas.0708608105
复制
发表时间：
2008-02-12
影响因子：
11.1
通讯作者：
Roberts, Richard J.
中科院分区：
文献类型：
--
作者：
Anton, Brian P.;Saleh, Lana;Roberts, Richard J.
核糖体蛋白S12在大肠杆菌和其他几种细菌中经历了独特的翻译后修饰，即残基D88的甲硫基化。利用质谱分析，我们已经确定了在大肠杆菌中负责这种修饰的酶。大肠杆菌中，yliG基因产物。这种酶，我们建议被称为RimO，是一种自由基-S-腺苷甲硫氨酸蛋白，具有很强的序列相似性MiaB，甲基硫醇tRNA。我们表明，RimO和MiaB代表两个更大的，古老的家庭可能的甲硫基转移酶，其中的其他两个是典型的枯草芽孢杆菌YqeV和詹氏甲烷球菌Mj 0867，我们预测，RimO是独特的这些亚组中的蛋白质的修饰，而不是tRNA。尽管如此，RimO在序列水平上甚至在C-末端TRAM结构域内也没有与其他三个亚组显著偏离，所述C-末端TRAM结构域在甲基转移酶鲁马中已知结合RNA底物，并且我们推测其负责甲基硫代转移酶的所有四个亚组中的底物结合和识别。据我们所知，RimO和MiaB代表了修饰蛋白质和核酸的酶之间相似性的最极端的已知情况。这里提出的初步结果构成了一个生物信息学驱动的预测与初步的实验验证，应该作为几个有趣的进一步调查的起点。
Ribosomal protein S12 undergoes a unique posttranslational modification, methylthiolation of residue D88, in Escherichia coli and several other bacteria. Using mass spectrometry, we have identified the enzyme responsible for this modification in E. coli, the yliG gene product. This enzyme, which we propose be called RimO, is a radical-S-adenosylmethionine protein that bears strong sequence similarity to MiaB, which methylthiolates tRNA. We show that RimO and MiaB represent two of four subgroups of a larger, ancient family of likely methylthiotransferases, the other two of which are typified by Bacillus subtilis YqeV and Methanococcus jannaschii Mj0867, and we predict that RimO is unique among these subgroups in its modification of protein as opposed to tRNA. Despite this, RimO has not significantly diverged from the other three subgroups at the sequence level even within the C-terminal TRAM domain, which in the methyltransferase RumA is known to bind the RNA substrate and which we presume to be responsible for substrate binding and recognition in all four subgroups of methylthiotransf erases. To our knowledge, RimO and MiaB represent the most extreme known case of resemblance between enzymes modifying protein and nucleic acid. The initial results presented here constitute a bioinformatics-driven prediction with preliminary experimental validation that should serve as the starting point for several interesting lines of further inquiry.