Studies on analysis of ribosomal RNA gene organization, phylogeny and evolution of spirochetes

为了研究某些螺旋体核糖体RNA基因的组织结构，将rRNA基因克隆到噬菌体Lambda EMBL3中。通过将限制性内切酶片段亚克隆到pUC18质粒DNA中，并对克隆进行Sourthern杂交分析，构建了rRNA基因的限制性内切酶图谱，确定了rRNA基因的结构。对致病性和非致病性密螺旋体的研究结果表明，RRS、RRL、RRF三种rRNA的基因紧密连锁，并在其基因组中出现两次。Fukna-ga等人，Microbiol。基因组杂交数据与莱姆病病原伯氏疏螺旋体rRNA基因重组质粒DNA的物理特性的相关性表明，与rDNA操纵子的一般组织结构不同，RRS基因是从紧密连锁和随机重复的RRL/RRF基因中分离出来的。真细菌…中rRNA基因的直接重复序列更多基因组是首次发现，这是真细菌rRNA基因组织的一个显著特征。等，J.Gen.Microbiol.，138，出版社和Fukunaga and Sohnaka，Biochem。Bishys公司。为阐明问号钩端螺旋体中编码rRNAs的转录单位的组织结构，测定了这些基因及其侧翼区的核苷酸序列，并通过引物延伸实验定位了转录本的5‘末端。结果表明，每个rRNA都是单独转录的，这与它们之间缺乏物理联系的事实是一致的。这是当时在真细菌中已知的唯一一种生物，其中所有的rRNA基因都存在并分别表达。我们还发现，在属于钩端螺旋体属和钩端螺旋体属的生物中，这些基因之间没有关联。此外，钩端螺旋体中RRF基因的数量与其寄生率有关。在非寄生型钩端螺旋体中，RRF有两个基因，而在寄生型钩端螺旋体中只有一个基因携带。福永等人，细菌学杂志，172,32643268,1990年，福永等人，微生物杂志，1371523-1528,1991年。较少

In order to study the organization of the ribosomal RNA genes of some spirochetes the rRNA genes were cloned in phage lambda EMBL3. By subcloning the re striction fragments into pUC18 plasmid DNA and analyzing the resulting clones by Sourthern blot hybridization, a restriction map of the rRNA genes was generated and the organization of the rRNA genes was determined. The results obtained from pathogenic and nonpathogenic treponemes show that the genes for three types of rRNA (rrs, rrl, rrf) are closely linked and occur twice in their genome. Fukuna-ga et al., Microbiol. Immunol., 36, 161-167, 1992.Correlation of genomic hybridization data with physical charactedrization of recombinant plasmid DNAs of the rRNA genes in Borrelia burgdorferi, the etiological agent of Lyme disease, showed that, in contrast to the general organization of rDNA operons ineubacteria, the rrs gene is separated from the closely linked and tandemly repeated rrl/rrf genes. Direct repeat of rRNA genes in eubacterial … More genome is the first discovery and this is a remarkable feature in the organization of the eubacterial rRNA genes. Fukunaga et al., J. Gen. Microbiol., 138, in press and Fukunaga and Sohnaka, Biochem. Bioshys. Res. Commun., in press.To elucidate the organization of the transcription units encoding the rRNAs in the Leptospira interrogans, the nucleotide sequences of the genes and their flanking regions were determined, and the 5' termini of the transcripts were mapped by primer extention experiments. The results show that each of the rRNAs is transcribed separately, and the fact is consistent with the lack of physical linkage among them. This was the only organism known in the eubacteria, at that time, in which all the rRNA genes are present and expressed separately. We also found that there is no linkage among those in the organisms belonging to the genera Leptospira and Leptonema. Furthermore, the number of rrf gene in leptospires was correlated with their parasitism. In the strains of nonparasitic leptospires, there are two genes for rrf, whereas only one gene is carried in parasitic leptospires. Fukunaga et al., J. Bacteriol., 172, 32643268, 1990., Fukunaga et al., J. Gen. Microbiol., 137, 1523-1528, 1991. Less