原核生物小RNA的研究及其进展

The advances of sRNA research in prokaryotes

原核生物中的小RNA(small RNA,sRNA)长度通常在50—250nt之间,一般在细胞内不被翻译,对基因转录后水平的调控发挥着关键作用。最初在大肠杆菌中发现,通过计算机预测和实验技术分析,查明的种类现已近140种,其作用机制包括;与目标mRNA的翻译起始位点或前导链结合分别抑制或促进翻译;或者模拟其他核酸的二级结构,去除mRNA结合蛋白对翻译的阻抑作用,促进翻译。此外,在转录水平上,sRNA还能模拟开放的启动子结构与RNA聚合酶结合阻止转录。

It was recently found that small RNAs （sRNAs） in prokaryotes are ranged in size from 50 to 250 nucleotides, are generally untranslated, and play key roles in post-transcriptional regulation. They were first discovered in Escherichia coli, and almost 140 sRNAs have been revealed by computational prediction and experimental approaches. It has made clear that the functional mechanism of sRNAs include inhibition or activation of translation by base pairing with the translation initiation sites or the leader segments on their target mRNAs. In addition, a few of them could mimic the secondary structures of other nucleic acids to derepress the translational inhibition by removing mRNA binding protein. Besides, some sRNAs could also mimic the DNA corresponding to an open promoter to sequester the RNA polymerase from mRNAs to block transcription.