The ribosomal RNA (rrn) operons of fast-growing mycobacteria: primary and secondary structures and their relation to rrn operons of pathogenic slow-growers.
The ribosomal RNA (rrn) operons of fast-growing mycobacteria: primary and secondary structures and their relation to rrn operons of pathogenic slow-growers.
复制标题
快速生长的分枝杆菌的核糖体 RNA (rrn) 操纵子：一级和二级结构及其与致病性缓慢生长者的 rrn 操纵子的关系。
作者：
Yuan;M. Colston;R. A. Cox
研究了耻垢分枝杆菌的两个核糖体 RNA (rrn) 操纵子（rrnA 和 rrnB）。通过PCR或反向PCR扩增前导区、部分16S rRNA基因、间隔区1区、部分23S rRNA基因和间隔区2区，并对产物进行克隆和测序。在前导区的 Box A 抗终止元件下游，没有检测到两个操纵子的序列存在差异。 Box A 的上游，在 rrnA 中发现了类似缓慢生长的 Box B 抗终止元件，但在 rrnB 中未发现。引物延伸实验表明，转录起始点位于 16S rRNA 基因 5' 端上游至少 370 个核苷酸处，且位于 Box A 元件附近的 RNase 加工位点处。推导了前 16S rRNA 和前 23S rRNA 的二级结构，它们与缓慢生长的分枝杆菌的相应结构不同，但密切相关。基于这些结果，有人提出，主分枝杆菌系中缓慢生长者的出现与跨越 rrnB 样操纵子的 DNA 片段的删除同时发生，从而使 rrnA 样操纵子成为 rRNA 的唯一来源。还提出了基于聚合酶和新生 30S 亚基之间对蛋白质 S10 和/或 Box A 序列的竞争，在 rrn 操纵子转录中需要两个 Box A 基序的解释。
The two ribosomal RNA (rrn) operons (rrnA and rrnB) of Mycobacterium smegmatis were investigated. The leader regions, part of the 16S rRNA genes, the spacer-1 regions, part of the 23S rRNA genes, and the spacer-2 regions were amplified by PCR or by inverse PCR and the products were cloned and sequenced. No differences in the sequences of the two operons were detected downstream from the Box A antitermination element of the leader region. Upstream from Box A a slow-grower-like Box B antitermination element was found in rrnA but not in rrnB. Primer extension experiments revealed that the start of transcription lies at least 370 nucleotides upstream from the 5'-end of the 16S rRNA gene and an RNase processing site near to the Box A element. Secondary structures were deduced for pre-16S rRNA and pre-23S rRNA which are distinct from, but closely related to, the corresponding structures of slow-growing mycobacteria. On the basis of these results it is proposed that the emergence of the slow-growers from the main mycobacterial line was coincident with the deletion of a segment of DNA spanning an rrnB-like operon, leaving an rrnA-like operon as the sole source of rRNA. An explanation is also proposed for the need for two Box A motifs in the transcription of an rrn operon based on competition between the polymerase and the nascent 30S subunit for either protein S10 and/or Box A sequences.
影响因子：
56.9
作者：
STERN, S;POWERS, T;NOLLER, HF
通讯作者：
NOLLER, HF