细菌非编码小RNA研究进展

细菌非编码小RNA(small non-coding RNA, sRNA)是一类长度在50~500个核苷酸, 不编码蛋白质的RNA。迄今, 在各种细菌中共发现超过150多种sRNA。它们通过碱基配对识别靶标mRNA, 在转录后水平调节基因的表达, 是细菌代谢、毒力和适应环境压力的重要调节因子。细菌sRNA的研究技术主要有基于生物信息学的计算机预测法和基于实验室的检测分析方法。这些方法所得到的sRNA都需要进行实验室确认, 然后再进一步通过各种实验手段研究其功能。     

细菌非编码小RNA的筛选及鉴定方法

细菌非编码小RNA（smallnon．codingRNAs,sRNAs）是一类长度为50～500nt、不编码蛋白质的功能RNA,在应对胁迫、毒力产生和新陈代谢等生命过程中起重要的调控作用。其主要通过碱基配对与靶mRNA发生作用,导致mRNA翻译和稳定性改变,从而在转录后水平调节基因的表达,最终影响细菌各种生命活动。近年来,利用生物信息学和分子生物学技术,已在细菌中筛选并鉴定得到了几百个sRNA。该文对细菌sRNA的筛选和鉴定方法作一简要综述。     

非编码小RNA对细菌毒力及耐药性的调控作用研究进展

近年来的研究发现,细菌非编码小RNA (small non-coding RNA, sRNA)对其不同生理进程起到了重要的调控作用。随着大量sRNA被发现并鉴定,细菌sRNA的功能被逐步阐明,其可在转录后水平广泛调控细菌的生理代谢、毒力及耐药性等。本文综述了sRNA对细菌毒力和耐药性调控作用的研究进展,对揭示细菌转录后水平毒力及耐药性调控机制具有一定意义。     

细菌小RNA的研究

小RNA(smallRNA,sRNA)在基因表达调控和生长发育等方面发挥着重要作用。细菌sRNA多通过与靶mRNA配对,转录后水平影响目的mRNA翻译或(和)稳定性,对基因的表达进行调节,以影响细胞的多种生理功能。本文从细菌sRNA与真核生物微RNA(microRNA,miRNA)的比较,sRNA的分类,sRNA分子伴侣Hfq及sRNA鉴别方法等方面综述了sRNA的研究进展,指出目前sRNA研究仍然存在的问题。原核生物中sRNA的大量发现和深入研究,有可能使人们对生物进化和生命的发展过程有更为深入的认识与了解。     

细菌小RNA的调控及在代谢工程中的应用

细菌代谢工程需要优化基因的表达来平衡代谢物通量分布和减少有毒的中间体积累,从而提高产物生物合成。细菌小RNA(small RNA,sRNAs)与靶标mRNA通过碱基互补配对结合来抑制或激活其靶标基因的表达。sRNA在细菌的生理过程中都起到了至关重要的调控作用,因此被认为是细菌代谢工程中调节靶标基因表达的有力工具。近年来,越来越多的人工合成sRNA在细菌代谢工程中得到应用,分别就细菌sRNA的靶标识别和其对靶标的调控及代谢工程中的应用做了总结概括。     

非编码小RNA的多样性

RNA是一类广泛存在的极其重要的生物大分子,它不仅种类繁多,而且不同种类的RNA在结构方面有着显著的差异。RNA种类和结构的多样性决定了RNA具有很多重要的生物学功能。随着对非编码RNA(non-coding RNA,ncRNA)研究的不断深入,ncRNAs同样呈现出前所未有的复杂性和多样性。主要介绍了tRNA、snRNA、scRNA、rRNA、siRNA、miRNA、pi RNA和nat-si RNA等两大类持家ncRNA和调控ncRNA的结构和功能,为便于了解生物体内小的非编码RNA的多样性,进一步挖掘和利用ncRNAs提供一定的参考,促使人们对RNA的认识和地位作出新的思考。     

非编码RNA与细菌耐药

细菌非编码RNA是一类新发现的基因表达调控因子,通过与靶mRNA配对,导致mRNA翻译和稳定性的变化,从而影响细胞的各种生理功能,如个体发育、翻译激活与抑制、细菌毒性等,而且一个单独的非编码RNA就能调控大量基因并对细胞生理产生深远影响。近年来诸多研究证实,非编码RNA与细菌耐药性也存在一定的关系。我们对此进行简要综述,为细菌耐药性的研究奠定基础。     

金黄色葡萄球菌非编码小RNA的研究进展

金黄色葡萄球菌(Staphylococcus aureus,S.aureus)是困扰全球公共卫生及人类健康的重要病原菌,其引起的各种临床感染与该菌表达的多种毒力因子密切相关,而这些毒力因子表达受到调节性因子的精确调控,在细菌致病机制中发挥着核心作用。非编码小RNA(Small non-coding RNA,s RNA)是基因表达的一类重要调节因子,可使细菌对环境因素做出反应,调节其应激适应性及毒力因子表达。但到目前为止,仅少数金黄色葡萄球菌s RNA的生物学功能得到阐述。本文将针对这些调节性s RNA的研究进展作一综述。     

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.     

日本血吸虫非编码小RNA研究进展

非编码小RNA是一类通过调节基因的表达从而影响生命活动的小分子,主要包括微小RNA、内源性小干扰RNA、Piwi蛋白相互作用的RNA及竞争性内源RNA。研究发现日本血吸虫感染动物后,宿主和虫体的非编码小RNA的表达水平均发生了改变。宿主源的非编码小RNA主要为微小RNA,其中miR-454和miR-203与日本血吸虫病发生发展有关,miR-223和miR-451与日本血吸虫自身生长发育有关;日本血吸虫非编码小RNA包括微小RNA、内源性小干扰RNA,这些非编码小RNA在日本血吸虫的生长、发育、性成熟及产卵中发挥着重要作用,如sjalet-7、sja-bantam,而且像sja-miR-3479和sja-miR-0001还可以诊断日本血吸虫病。就日本血吸虫非编码小RNA的研究进展进行综述,为日本血吸虫病的防治提供参考。     

细菌非编码小RNA功能及作用机制研究进展

生物体中除了编码蛋白质的mRNA外,还存在多种具有重要调控功能的非编码RNA。细菌中长度50~500 nt的非编码RNA通常定义为sRNA。sRNA在细菌的整个生命活动中发挥着极为广泛的作用,在感受环境压力、基因表达、细胞周期乃至个体发育等过程中均具有重要的调控作用。sRNA的功能学和调控机制的研究已成为当今细菌学研究的热点。本研究就细菌中的sRNA的特征,在细菌中的作用和作用机制进行文献综述。     

Artificial trans-encoded small non-coding RNAs specifically silence the selected gene expression in bacteria

Recently, many small non-coding RNAs (sRNAs) with important regulatory roles have been identified in bacteria. As their eukaryotic counterparts, a major class of bacterial trans-encoded sRNAs acts by basepairing with target mRNAs, resulting in changes in translation and stability of the mRNA. RNA interference (RNAi) has become a powerful gene silencing tool in eukaryotes. However, such an effective RNA silencing tool remains to be developed for prokaryotes. In this study, we described first the use of artificial trans-encoded sRNAs (atsRNAs) for specific gene silencing in bacteria. Based on the common structural characteristics of natural sRNAs in Gram-negative bacteria, we developed the designing principle of atsRNA. Most of the atsRNAs effectively suppressed the expression of exogenous EGFP gene and endogenous uidA gene in Escherichia coli. Further studies demonstrated that the mRNA base pairing region and AU rich Hfq binding site were crucial for the activity of atsRNA. The atsRNA-mediated gene silencing was Hfq dependent. The atsRNAs led to gene silencing and RNase E dependent degradation of target mRNA. We also designed a series of atsRNAs which targeted the toxic genes in Staphyloccocus aureus, but found no significant interfering effect. We established an effective method for specific gene silencing in Gram-negative bacteria.     

链球菌非编码小RNA研究进展

非编码小RNA(Small non-coding RNA,sRNA)是一种存在于原核和真核生物中的新型调控RNA,长度约为40～500个核苷酸。作为一类关键的调控因子,sRNA通过与靶mRNA或蛋白质结合来调控细胞内的基因表达。大部分细菌sRNA在大肠杆菌等革兰氏阴性菌中被发现并研究,但近十年来越来越多的sRNA在革兰氏阳性菌中被逐步发现。作为一类革兰氏阳性菌,链球菌属中sRNA目前研究主要集中在毒力调节,鲜有其他调控的报道。本文总结了链球菌中sRNA的最新进展,并介绍其主要功能和机理,以期为细菌sRNA研究提供借鉴。     

Identification of small non-coding RNAs from mitochondria and chloroplasts

Small non-protein-coding RNAs (ncRNAs) have been identified in a wide spectrum of organisms ranging from bacteria to humans. In eukarya, systematic searches for ncRNAs have so far been restricted to the nuclear or cytosolic compartments of cells. Whether or not small stable non-coding RNA species also exist in cell organelles, in addition to tRNAs or ribosomal RNAs, is unknown. We have thus generated cDNA libraries from size-selected mammalian mitochondrial RNA and plant chloroplast RNA and searched for small ncRNA species in these two types of DNA-containing cell organelles. In total, we have identified 18 novel candidates for organellar ncRNAs in these two cellular compartments and confirmed expression of six of them by northern blot analysis or RNase A protection assays. Most candidate ncRNA genes map to intergenic regions of the organellar genomes. As found previously in bacteria, the presumptive ancestors of present-day chloroplasts and mitochondria, we also observed examples of antisense ncRNAs that potentially could target organelle-encoded mRNAs. The structural features of the identified ncRNAs as well as their possible cellular functions are discussed. The absence from our libraries of abundant small RNA species that are not encoded by the organellar genomes suggests that the import of RNAs into cell organelles is of very limited significance or does not occur at all.     

Diversity of endogenous small non-coding RNAs in Oryza sativa

Small non-coding RNAs play important roles in regulating cell functions by controlling mRNA turnover and translational repression in eukaryotic cells. Here we isolated 162 endogenous small RNA molecules from Oryza sativa, which ranged from 16 to 35 nt in length. Further analysis indicated that they represented a diversity of small RNA molecules, including 17 microRNAs (miRNAs), 30 tiny non-coding RNAs (tncRNAs) and 20 repeat-associated small interfering RNAs (rasiRNAs). Among 17 miRNAs, 13 were novel miRNA candidates and their potential targets were important regulatory genes in the rice genome. We also found that a cluster of small RNAs, including many rasiRNAs, matched to a nuclear DNA fragment that evolutionarily derived from chloroplast. These results demonstrate clearly the existence of distinct types of small RNAs in rice and further suggest that small RNAs may control gene regulation through diverse mechanisms.