Todo Kozo, Goto Takatsugu, Honda Akio, Tamura Mieko, Miyamoto Kazuaki, Fujita Shigeyuki, Akimoto Shigeru
Department of Microbiology, Wakayama Medical University, Wakayama, Japan.
Syst Appl Microbiol. 2004 Feb;27(1):18-26. doi: 10.1078/0723-2020-00247.
There are four rRNA operons rrnA, rrnB, rrnC and rrnD on the genome of Finegoldia magna (formerly Peptostreptococcus magnus) ATCC29328, which, in contrast to those of Clostridia, are dispersed around the chromosome. Using a BAC library we determined the nucleotide sequences and structures of all four operons, including their flanking regions, and performed comparative analyses. We identified putative boxA sequences in the operons, which should be required for rRNA transcription antitermination, as well as their respective tandem promoters, AT-rich UP elements in the upstream region and Rho-independent terminators in the downstream region. The mosaic features of the operons were revealed. Multiple tRNAs were identified in the downstream region of two operons, 18 in rrnC and 11 in rrnD. They were presumed to form transcription units together with rRNAs. rrnA and rrnB had repeat units with Rho-independent terminators instead of tRNAs in the downstream region. rrnB and rrnC were the most similar in rrn upstream promoter region. Focusing on the sequence variations of rRNA genes, rrnB alone was heterogeneous. In light of previous reports, we also assessed the correlation between intercistronic rRNA sequence differences and distances between the operons, but no positive correlation was seen in this strain.
在巨大芬戈尔德菌（以前称为巨大消化链球菌）ATCC29328的基因组上有四个rRNA操纵子，即rrnA、rrnB、rrnC和rrnD，与梭菌的rRNA操纵子不同，它们分散在染色体周围。我们使用一个BAC文库确定了所有四个操纵子的核苷酸序列和结构，包括其侧翼区域，并进行了比较分析。我们在操纵子中鉴定出了推测的boxA序列，rRNA转录抗终止可能需要这些序列，以及它们各自的串联启动子、上游区域富含AT的UP元件和下游区域的不依赖Rho的终止子。揭示了操纵子的镶嵌特征。在两个操纵子的下游区域鉴定出多个tRNA，rrnC中有18个，rrnD中有11个。它们被推测与rRNA一起形成转录单元。rrnA和rrnB在下游区域有带有不依赖Rho终止子的重复单元，而不是tRNA。rrnB和rrnC在rrn上游启动子区域最为相似。聚焦于rRNA基因的序列变异，只有rrnB是异质的。根据以前的报道，我们还评估了顺反子间rRNA序列差异与操纵子之间距离的相关性，但在该菌株中未发现正相关。
