Amador Eladio, Castro José M, Correia Antonio, Martín Juan F
Area of Microbiology, Department of Ecology, Genetics and Microbiology, Faculty of Biology, University of León, 24071 León, Spain.
Area de Microbiologia, Dpt. de Biologia, Universidade de Aveiro, 3800 Aveiro, Portugal.
Microbiology (Reading). 1999 Apr;145 ( Pt 4):915-924. doi: 10.1099/13500872-145-4-915.
Five rRNA operons (rrn) were found by hybridization in the genome of 'Brevibacterium lactofermentum' ATCC 13869 and Corynebacterium glutamicum ATCC 13032. 'B. lactofermentum' DSM 20412 differed from the other corynebacteria tested in showing six hybridizing BamHI bands. Two of the rrn operons (rrnD and rrnE) were located in a single cosmid. Sequencing of the rrnD operon showed that it contains a complete 16S rRNA-23S RNA-5S rRNA gene cluster. Phylogenetic studies using the complete 16S rRNA sequence showed that 'B. lactofermentum' is closely related to several species of the genus Corynebacterium but only distantly related to the type species Brevibacterium linens and the authors suggest that it should be reclassified as Corynebacterium lactofermentum. The 5' end of mature 16S rRNA was identified by primer extension. Sequence elements similar to those of mycobacteria implicated in transcription antitermination (Boxes A, B, C) and in processing of the pre-rRNA to 16S rRNA were identified. An open reading frame encoding an rpoD-like sigma factor (named SigC) different from the previously reported SigA and SigB proteins was found upstream of rrnD in the opposite orientation. Both rpoD and sigC seem to be expressed from a bidirectional promoter region.
通过杂交在乳酸发酵短杆菌ATCC 13869和谷氨酸棒杆菌ATCC 13032的基因组中发现了5个rRNA操纵子(rrn)。乳酸发酵短杆菌DSM 20412与其他测试的棒状杆菌不同,显示出6条杂交的BamHI条带。其中两个rrn操纵子(rrnD和rrnE)位于单个黏粒中。rrnD操纵子的测序表明它包含一个完整的16S rRNA - 23S rRNA - 5S rRNA基因簇。使用完整的16S rRNA序列进行的系统发育研究表明,乳酸发酵短杆菌与棒状杆菌属的几个物种密切相关,但与模式种亚麻短杆菌关系较远,作者建议将其重新分类为乳酸发酵棒杆菌。通过引物延伸鉴定了成熟16S rRNA的5'末端。鉴定出了与分枝杆菌中参与转录抗终止(A、B、C框)以及前体rRNA加工成16S rRNA的序列元件相似的序列元件。在rrnD上游以相反方向发现了一个编码与先前报道的SigA和SigB蛋白不同的rpoD样σ因子(命名为SigC)的开放阅读框。rpoD和sigC似乎都从双向启动子区域表达。