Bricker B J
National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA.
Gene. 2000 Sep 5;255(1):117-26. doi: 10.1016/s0378-1119(00)00273-0.
The three Brucella melitensis ribosomal RNA operons rrnA, rrnB, and rrnC were characterized individually. Each locus consisted of the 16S rRNA gene (rrs), followed by an intergenic spacer containing the tRNA-Ile and tRNA-Ala genes, the 23S rRNA gene (rrl), an intergenic spacer devoid of tRNA genes, the 5S rRNA gene (rrf), and an f-Met tRNA gene. The DNA sequences were identical over a 6271bp region, diverging 594bp upstream of rrs and immediately downstream of the f-Met tRNA gene. The previously uncharacterized 23S rRNA genes each contained a 178bp insertion 130bp from the 5' end. The location of the insertion matched intervening sequences (IVSs) found in other Rhizobiaceae. However, the size and sequence of the Brucella IVS differed from all previously reported IVS sequences from bacteria. The IVS region was PCR-amplified from 20 Brucella isolates representing all known Brucella species and biovars. All isolates contained only the complete IVS fragment. We compared the IVS DNA sequences of rrlC from representative strains of each of the six known Brucella species. The data revealed that the sequences were identical and differed from the B. melitensis IVS sequences by a single base pair. In other bacterial species, the IVSs are associated with post-transcriptional processing of the 23S rRNA by RNase III. We found that the Brucella 23S rRNA was slightly smaller than the 23S rRNA of Escherichia coli, known to be devoid of IVS sequences.
对布鲁氏菌（Brucella melitensis）的三个核糖体RNA操纵子rrnA、rrnB和rrnC进行了单独表征。每个位点由16S rRNA基因（rrs）组成，其后是一个包含tRNA - Ile和tRNA - Ala基因的基因间隔区，23S rRNA基因（rrl），一个不含tRNA基因的基因间隔区，5S rRNA基因（rrf）和一个f - Met tRNA基因。在一个6271bp的区域内，DNA序列是相同的，在rrs上游594bp处以及f - Met tRNA基因下游立即出现分歧。之前未被表征的23S rRNA基因在距5'端130bp处各自包含一个178bp的插入片段。该插入片段的位置与在其他根瘤菌科中发现的间隔序列（IVS）相匹配。然而，布鲁氏菌IVS的大小和序列与之前报道的所有细菌IVS序列不同。从代表所有已知布鲁氏菌物种和生物变种的20株布鲁氏菌分离株中PCR扩增IVS区域。所有分离株仅包含完整的IVS片段。我们比较了六个已知布鲁氏菌物种中每个物种的代表性菌株的rrlC的IVS DNA序列。数据显示这些序列是相同的，并且与布鲁氏菌IVS序列仅相差一个碱基对。在其他细菌物种中，IVS与RNase III对23S rRNA的转录后加工相关。我们发现布鲁氏菌的23S rRNA比已知不含IVS序列的大肠杆菌的23S rRNA略小。
