细菌非编码小RNA分子RyhB的结构与功能

RyhB是一种大小为90个核苷酸的细菌非编码小RNA分子(small noncoding RNA, sRNA).当铁缺乏时，RyhB通过下调一系列与铁的储存和利用相关蛋白的表达水平以维持体内的铁平衡，而其本身的表达则受到负调控因子Fur(ferric uptake regulator)的调节.在体内，RyhB与Hfq蛋白和核糖核酸酶E (ribonuclease E, RNase E)形成核蛋白复合物sRNP来发挥活性.sRNP通过RyhB与靶基因的互补配对序列作用于靶基因的核糖体结合位点，阻断靶mRNA的翻译，并迅速引起靶mRNA的降解.此外，RyhB还可以通过影响致病菌的生物膜形成、趋化性、耐酸性等方面的能力对细菌的致病力进行调节.本文综述了RyhB的结构、功能及作用机制方面的研究进展，并对其存在的生理意义进行了探讨.

Structure and Function of Bacterial Small Noncoding RNA RyhB

RyhB is a 90 nucleotide bacterial small noncoding RNA (sRNA). It down-regulates a set of iron-storage and iron-using proteins when iron is limiting. However, it is itself negatively regulated by the ferric uptake repressor protein, Fur (ferric uptake regulator). In vivo, RyhB forms a ribonucleoprotein complex with the Hfq-RNase E protein complex to act on the ribosome-binding site of target mRNAs through RNA-RNA base-pairing. This ribonucleoprotein complex, which is called sRNP, could lead to translational repression and rapid mRNA degradation of target gene. In addition, RyhB could modulate the virulence of bacterial pathogens by regulating genes involved in motility, chemotaxis, biofilm formation and acid resistance. This review is mainly focused on current research in the structure, biological function and molecular mechanism of sRNA RyhB. The physiological significance of this small RNA was discussed further.