原核细胞microRNA特性及其作用机制研究进展

Advance in research of characteristics and action mechanism of microRNAs from prokaryotes

microRNA为一类非编码小RNA,主要通过其种子序列(seed sequence,SS)与靶mRNA位于5′端的SS结合序列特异性结合后抑制靶mRNA转录或降解靶mRNA,从而在转录后水平负调控靶基因表达。microRNA首先发现于秀丽隐杆线虫(Caenorhabditis elegans),此后发现各种真核细胞均存在大量各种microRNA。真核细胞首先转录出microRNA前体,经剪切后成为21~23nt有功能的microRNA,大多与靶mRNA的3′端序列结合后引起靶mRNA翻译抑制或降解。近年不少细菌等原核细胞microRNA被发现,但原核细胞microRNA不需剪切即有活性,大小为50~400nt,其特性、作用位点和机制等也与真核细胞有一定差异。本文简要介绍真核和原核细胞基因表达调控主要机制、microRNA特点及其调控基因表达的机制,以期为深入研究原核细胞型病原微生物基因表达调控与致病机制奠定基础。

microRNAs is a group of small non-coding RNAs that play a negative regulation role in expression of target genes at post-transcriptional level by inhibition or degradation of target mRNAs after combination of the seed sequence （SS） in microRNAs with the SS-binding sequences usually located at 5＇ ends of target mRNAs. microRNAs was firstly found in Caenorhabditis elegans. Subsequently, many different microRNAs in eukaryocytes were revealed. In eukaryocytes, microRNA precursors are transcribed at first and then become functional microRNAs with 21-23 nt in size after splice. Most of eukaryocytic microRNAs combime with the sequences at 3＇ end of target mRNAs that cause the translation inhibition or degradation of the mRNAs. In the recent years, many different prokaryocytes, such as bacteria, have been confirmed to possess microRNAs. However, the microRNAs in prokaryotes such as bacteria are 50-400 nt in size and have the biological activity without splice. Moreover, the characteristics, action sites and mechanisms of the prokaryotic microRNAs have some certain diversity compared to the eukaryotic microRNAs. Our review briefly introduce the major regulation mechanisms of gene expression as well as the general characteristics of microRNAs and their regulation mechanisms of gene expression in prokaryocytes and eukaryocytes, which will provide a basis for further and profound study on the gene expression regulation and pathogenic mechanisms of prokaryotic microbial pathogens.