细菌Hfq蛋白的结构、功能及作用机制

非编码小RNA(small RNA, sRNA)是细菌基因转录后调控的一个重要层次,也是近十年来原核生物研究领域的焦点之一。大多数sRNA的作用与Hfq蛋白密切相关,即Hfq可以促进sRNA与其靶标mRNA的互补配对,进而影响翻译的进行或者mRNA的稳定性。笔者对Hfq的结构、Hfq参与sRNA调节作用的机制、Hfq在多种细菌中的功能表型进行了综述。Hfq是一个保守的蛋白质,在很多细菌中广泛存在,并与真核生物中参与mRNA剪切与降解活动的Sm蛋白同源。在结构上,Hfq具有两个非等同的RNA结合面,可以结合并介导多个RNA分子的相互作用,其结构体现了和功能的高度统一性。目前,对Hfq的研究主要集中于革兰氏阴性细菌中,在革兰氏阳性细菌中,Hfq的功能尚不明晰; 此外,在许多重要的细菌中,Hfq影响功能表型的具体机制也不清楚。因此,今后有必要进一步精细研究Hfq的分子结构特征和功能特点,深入分析Hfq对细菌表型多样化的影响机制,探究Hfq影响靶标分子和功能表型的详尽机制。     

微生物氮代谢调控研究进展

氮素是核酸及蛋白质的主要成分,也是构成生物体的必需元素,对微生物的生长发育、次生代谢以及信息交流等方面均有重要作用.为维持自身的生长发育,不同微生物进化出特有的代谢调控系统,以应对不断变化的氮素供应环境.目前所知的代谢调控方式主要有GlnR、Ntr、sRNA调控系统,但不同的调控系统之间区别甚大.该文综述了几种常见的氮代谢调控系统,以期为深入了解并运用微生物的氮代谢调控机制提供参考.     

Phylogeny of higher taxa of hexapoda according to 12sRNA sequences

The phylogenetic relationship of Hexapoda has been debated for a long time, which will be resolved mainly depending on the settlement of monophyly, affinities and interrelationships among Protura, Collembola and Diplura. Mitochondrial 12sRNA gene about 355 bp fragments from one proturan species, two collembolan species, two dipluran species and one oribatid species were sequenced. The Kimura 2-parameter distances were calculated and a series of molecular phylogenetic trees were reconstructed by using the N-J method, from which the following points were drawn: (ⅰ) Protura and Collembola compose a monophyletic group representing absent-cerci; (ⅱ) Diplura is not a monophyletic group, in which Campodeoid with filiform cerci belongs to a clade and Japygoid with pincer cerci and Ectognatha compose another clade, that is, Insecta s. str. stemmed from Japygoid. So it would be suggested that the phylogenetic relationship of Hexapoda is [Parainsecta (Collembola + Protura) +Campodeoid +Insecta (Japygoid + Ectognatha)].