Ribosomal RNA contains many posttranscriptionally modified nucleosides, particularly in the functional parts of the ribosome. The distribution of these modifications varies from one organism to another. In Bacillus subtilis, the model organism for Gram-positive bacteria, mass spectrometry experiments revealed the presence of 7-methylguanosine (m⁷G) at position 2574 of the 23S rRNA, which lies in the A-site of the peptidyl transferase center of the large ribosomal subunit. Testing several m⁷G methyltransferase candidates allowed us to identify the RlmQ enzyme, encoded by the ywbD open reading frame, as the MTase responsible for this modification. The enzyme methylates free RNA and not ribosomal 50S or 70S particles, suggesting that modification occurs in the early steps of ribosome biogenesis.

中文翻译：

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枯草芽孢杆菌 ywbD 基因编码 RlmQ，即在肽基转移酶中心的 A 位点形成 m7G2574 的 23S rRNA 甲基转移酶

核糖体 RNA 含有许多转录后修饰的核苷，特别是在核糖体的功能部分。这些修饰的分布因一种生物体而异。在枯草芽孢杆菌（革兰氏阳性菌的模型生物）中，质谱实验揭示了23S rRNA 的 2574 位存在7-甲基鸟苷 (m ⁷ G)，该位置位于细菌肽基转移酶中心的 A 位点。大核糖体亚基。测试几个 m ^{7 G 甲基转移酶候选物使我们能够识别出由}ywbD开放阅读框编码的 RlmQ 酶，作为负责这种修饰的 MTase。该酶甲基化游离 RNA，而不是核糖体 50S 或 70S 颗粒，表明修饰发生在核糖体生物发生的早期步骤。