Substrate recognition by class I lysyl-tRNA synthetases:: A molecular basis for gene displacement
Substrate recognition by class I lysyl-tRNA synthetases:: A molecular basis for gene displacement
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DOI：
10.1073/pnas.96.2.418
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发表时间：
1999-01-19
影响因子：
11.1
通讯作者：
Söll, D
中科院分区：
文献类型：
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作者：
Ibba, M;Losey, HC;Söll, D
赖氨酰-tRNA合成酶（LysRS）在氨酰-tRNA合成酶中是独特的，其由不相关的I类和II类酶组成。为了允许两种类型的LysRS之间的直接比较，检查I类LysRS的底物识别。编码古细菌和细菌I类酶的基因能够拯救LysRS缺陷的大肠杆菌菌株，表明它们在体内功能上替代L1类LysRS的能力。体外表征显示赖氨酸活化和识别是tRNA依赖性的，这是几种I类而不是II类氨酰-tRNA合成酶的属性，对tRNA识别的检测表明，I类LysRS识别tRNA（Lys）中与其II类对应物相同的元件，即tRNA碱基（N73）和反密码子，这两种不相关的酶对tRNA（Lys）中相同核苷酸的序列特异性识别表明，在翻译机构的进化中，tRNA（Lys）至少先于一种LysRS，唯一观察到的变化是，G2.U71摆动对螺旋体tRNA（赖氨酸）作为反决定簇的II类LysRS，但不改变I类酶的识别。tRNA识别的这种差异强烈支持使用I类酶来氨酰化特定的tRNA（Lys）种类，并为在某些细菌中观察到的I类LysRS对II类的置换提供了分子基础。
Lysyl-tRNA synthetases (LysRSs) are unique amongst the aminoacyl-tRNA synthetases in being composed of unrelated class I and class II enzymes, To allow direct comparison between the two types of LysRS, substrate recognition by class I LysRSs was examined. Genes encoding both an archaeal and a bacterial class I enzyme were able to rescue an Escherichia coli strain deficient in LysRS, indicating their ability to functionally substitute for a class LI LysRS in vivo, In vitro characterization showed lysine activation and recognition to be tRNA-dependent, an attribute of several class I, but not class II, aminoacyl-tRNA synthetases, Examination of tRNA recognition showed that class I LysRSs recognize the same elements in tRNA(Lys) as their class II counterparts, namely the discriminator base (N73) and the anticodon, This sequence-specific recognition of the same nucleotides in tRNA(Lys) by the two unrelated types of enzyme suggests that tRNA(Lys) predates at least one of the LysRSs in the evolution of the translational apparatus, The only observed variation in recognition was that the G2.U71 wobble pair of spirochete tRNA(Lys) acts as antideterminant for class II LysRS but does not alter class I enzyme recognition. This difference in tRNA recognition strongly favors the use of a class I-type enzyme to aminoacylate particular tRNA(Lys) species and provides a molecular basis for the observed displacement of class II by class I LysRSs in certain bacteria.