tRNAVal允许在Lactobacillus casei中的摇摆位置使用未经修改的尿素进行四向解码
Riko Sugita1, Vincent Guérineau2, David Touboul3
1Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
概括
瓦林使用未经修改的U34来对所有瓦林编码子进行四向解码. 这挑战了以前关于tRNA修饰和细菌中的编码子识别的假设.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 细菌tRNA摇摆位置的修改,如5-基尤里丁 (ho5U) 衍生物,通过启用非沃森-克里克基配对,对于识别符号家族至关重要.
- 这些修改允许U34与A,G,有时C配对,影响解码特异性.
- 虽然格拉姆阳性细菌通常具有mo5U,而格拉姆阴性细菌具有cmo5U/mcmo5U,但一些生物体,如菌体,线粒体和叶绿体,利用未经修改的U34进行四向解码.
研究的目的:
- 为了研究tRNA Valine在Lactobacillus casei中的解码机制,这是一种缺乏已知的xo5U生物合成基因的グラム阳性细菌.
- 为了确定一个未表征的tRNA基因 (tRNAUnd) 与GAC抗在L. casei.中是否表达和功能.
- 阐明L. casei tRNAVal(UAC) 中的U34修饰的作用及其解码所有氨酸编码子的能力.
主要方法:
- 在L. casei tRNAVal中确认未经修改的U34.
- 在L.casei细胞中对tRNAUnd基因表达的分析.
- 采用L. casei valyl-tRNA合成酶和体外转录tRNA的体外氨基化试验.
- 核糖体结合测试以评估tRNAVal(UAC) 与所有四个valine编码子的相互作用.
主要成果:
- 在Lactobacillus casei tRNAVal中的U34被证实是未经修改的.
- 在L.casei细胞中没有检测到假定tRNAUnd基因的表达.
- 在体外研究表明,tRNAUnd不能被L. casei valyl-tRNA合成酶氨基化.
- 原生tRNAVal(UAC) 与未经修改的U34有效地结合于核糖体A位点中的所有四个valine编码.
结论:
- 乳杆菌casei tRNAVal(UAC) 使用四向解码,使用未经修改的U34来识别所有四个氨酸编码子 (GUU,GUC,GUA,GUG).
- 这种解码策略与在Mycoplasma物种,线粒体和叶绿体中观察到的类似.
- 这些发现表明,L.casei依赖于未经修改的tRNA进行全面的氨基密码子识别,与其他细菌所见的典型xo5U修改途径分歧.
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