Hipps D, Schimmel P
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
EMBO J. 1995 Aug 15;14(16):4050-5. doi: 10.1002/j.1460-2075.1995.tb00076.x.
RNA minihelices which reconstruct the 12 base pair acceptor-T psi C domains of transfer RNAs interact with their cognate tRNA synthetases. These substrates lack the anticodons of the genetic code and, therefore, cannot participate in steps of protein synthesis subsequent to aminoacylation. We report here that expression in Escherichia coli of either of two minihelices, each specific for a different amino acid, inhibited cell growth. Inhibition appears to be due to direct competition between the minihelix and its related tRNA for binding to their common synthetase. This competition, in turn, sharply lowers the pool of the specific charged tRNA for protein synthesis. Inhibition is relieved by single nucleotide changes which disrupt the minihelix-synthetase interaction. The results suggest that sequence-specific RNA minihelix substrates bind to cognate synthetases in vivo and can, in principle, act as cell growth regulators. Naturally occurring non-tRNA substrates for aminoacylation may serve a similar purpose.
重建转运RNA 12个碱基对的受体-TψC结构域的RNA小螺旋与它们对应的氨酰-tRNA合成酶相互作用。这些底物缺乏遗传密码的反密码子，因此不能参与氨基酰化之后的蛋白质合成步骤。我们在此报告，两种小螺旋中的任何一种在大肠杆菌中的表达（每种小螺旋对不同的氨基酸具有特异性）都会抑制细胞生长。抑制作用似乎是由于小螺旋与其相关的转运RNA之间直接竞争与它们共同的合成酶结合。反过来，这种竞争会大幅降低用于蛋白质合成的特定带电转运RNA的库。通过破坏小螺旋-合成酶相互作用的单核苷酸变化可以缓解抑制作用。结果表明，序列特异性RNA小螺旋底物在体内与对应的合成酶结合，并且原则上可以作为细胞生长调节剂。天然存在的用于氨基酰化的非转运RNA底物可能具有类似的作用。
