Agmatidine, a modified cytidine in the anticodon of archaeal tRNAIle, base pairs with adenosine but not with guanosine
Agmatidine, a modified cytidine in the anticodon of archaeal tRNAIle, base pairs with adenosine but not with guanosine
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DOI：
10.1073/pnas.0914869107
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发表时间：
2010-02-16
影响因子：
11.1
通讯作者：
RajBhandary, Uttam L.
中科院分区：
文献类型：
--
作者：
Mandal, Debabrata;Koehrer, Caroline;RajBhandary, Uttam L.
细菌和古生菌的AUA解码tRNA(Ile) (tRNA（2)(Ile)）的第一个反密码子位置胞苷的修饰是该tRNA读取异亮氨酸密码子AUA并区分AUA和蛋氨酸密码子aug的必要条件。为了鉴定古细菌中修饰的胞苷，我们从Haloarcula marismortui中纯化了该tRNA物种，建立了其密码子读取特性。采用液相色谱-质谱法（LC-MS）将RNase A和T1酶切产物定位到tRNA上，并采用LC-MS/MS对RNase A酶切产物的寡核苷酸进行测序。这些分析表明，tRNA(2)（Ile）反密码子中胞苷的修饰使其分子质量增加了112个质量单位，并使糖苷键在质谱分析中异常不稳定。准确的质谱LC-MS和LC-MS/ MS分析表明，tRNA(2)（Ile）的总核苷酶切结果表明，c2 -氧基的修饰胞苷缺失，并通过仲胺连锁被agmatine（脱羧精氨酸）取代。我们建议将这种修饰后的胞苷命名为agmatidine，缩写为C+。Agmatidine也存在于maripaludis Methanococcus tRNA(2)（Ile）和Sulfolobus solfataricus total tRNA中，表明其可能存在于euryarchaea和crenarchaea的解码tRNA（Ile）的AUA中。对agmatidine的鉴定表明，细菌和古细菌在读取异亮氨酸密码子AUA和识别蛋氨酸密码子AUG方面具有非常相似的策略。
Modification of the cytidine in the first anticodon position of the AUA decoding tRNA(Ile) (tRNA(2)(Ile)) of bacteria and archaea is essential for this tRNA to read the isoleucine codon AUA and to differentiate between AUA and the methionine codon AUG. To identify the modified cytidine in archaea, we have purified this tRNA species from Haloarcula marismortui, established its codon reading properties, used liquid chromatography-mass spectrometry (LC-MS) to map RNase A and T1 digestion products onto the tRNA, and used LC-MS/MS to sequence the oligonucleotides in RNase A digests. These analyses revealed that the modification of cytidine in the anticodon of tRNA(2)(Ile) adds 112 mass units to its molecular mass and makes the glycosidic bond unusually labile during mass spectral analyses. Accurate mass LC-MS and LC-MS/ MS analysis of total nucleoside digests of the tRNA(2)(Ile) demonstrated the absence in the modified cytidine of the C2-oxo group and its replacement by agmatine (decarboxy-arginine) through a secondary amine linkage. We propose the name agmatidine, abbreviation C+, for this modified cytidine. Agmatidine is also present in Methanococcus maripaludis tRNA(2)(Ile) and in Sulfolobus solfataricus total tRNA, indicating its probable occurrence in the AUA decoding tRNA(Ile) of euryarchaea and crenarchaea. The identification of agmatidine shows that bacteria and archaea have developed very similar strategies for reading the isoleucine codon AUA while discriminating against the methionine codon AUG.