Lu M, Draper D E
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
Nucleic Acids Res. 1995 Sep 11;23(17):3426-33. doi: 10.1093/nar/23.17.3426.
Ribosomal protein L11 and an antibiotic, thiostrepton, bind to the same highly conserved region of large subunit ribosomal RNA and stabilize a set of NH4(+)-dependent tertiary interactions within the domain. In vitro selection from partially randomized pools of RNA sequences has been used to ask what aspects of RNA structure are recognized by the ligands. L11-selected RNAs showed little sequence variation over the entire 70 nucleotide randomized region, while thiostrepton required a slightly smaller 58 nucleotide domain. All the selected mutations preserved or stabilized the known secondary and tertiary structure of the RNA. L11-selected RNAs from a pool mutagenized only around a junction structure yielded a very different consensus sequence, in which the RNA tertiary structure was substantially destabilized and L11 binding was no longer dependent on NH4+. We propose that L11 can bind the RNA in two different 'modes', depending on the presence or absence of the NH4(+)-dependent tertiary structure, while thiostrepton can only recognize the RNA tertiary structure. The different RNA recognition mechanisms for the two ligands may be relevant to their different effects on protein synthesis.
核糖体蛋白L11和抗生素硫链丝菌素与大亚基核糖体RNA的同一高度保守区域结合，并稳定该结构域内一组依赖于NH4(+)的三级相互作用。从部分随机的RNA序列库中进行体外筛选，以探究配体识别RNA结构的哪些方面。L11筛选出的RNA在整个70个核苷酸的随机区域内序列变化很小，而硫链丝菌素需要一个稍小的58个核苷酸的结构域。所有选定的突变都保留或稳定了RNA已知的二级和三级结构。从仅在连接结构周围诱变的文库中筛选出的L11 RNA产生了非常不同的共有序列，其中RNA三级结构显著不稳定，L11结合不再依赖于NH4(+)。我们提出，L11可以根据是否存在依赖于NH4(+)的三级结构，以两种不同的“模式”结合RNA，而硫链丝菌素只能识别RNA三级结构。两种配体不同的RNA识别机制可能与它们对蛋白质合成的不同影响有关。
