Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, Bochum, Germany.
J Bacteriol. 2012 Apr;194(8):1849-59. doi: 10.1128/JB.06274-11. Epub 2012 Jan 27.
The copper-regulated Rhodobacter capsulatus cutO (multicopper oxidase) gene confers copper tolerance and is carried in the tricistronic orf635-cutO-cutR operon. Transcription of cutO strictly depends on the promoter upstream of orf635, as demonstrated by lacZ reporter fusions to nested promoter fragments. Remarkably, orf635 expression was not affected by copper availability, whereas cutO and cutR were expressed only in the presence of copper. Differential regulation was abolished by site-directed mutations within the orf635-cutO intergenic region, suggesting that this region encodes a copper-responsive mRNA element. Bioinformatic predictions and RNA structure probing experiments revealed an intergenic stem-loop structure as the candidate mRNA element. This is the first posttranscriptional copper response mechanism reported in bacteria.
铜调节的荚膜红细菌 cutO(多铜氧化酶)基因赋予铜耐受性,并存在于三顺反子 orf635-cutO-cutR 操纵子中。如通过 lacZ 报告基因融合到嵌套启动子片段所证明的那样,cutO 的转录严格依赖于 orf635 上游的启动子。值得注意的是,orf635 的表达不受铜供应的影响,而 cutO 和 cutR 仅在存在铜的情况下表达。在 orf635-cutO 基因间区的定点突变中消除了差异调节,表明该区域编码一个铜响应的 mRNA 元件。生物信息学预测和 RNA 结构探测实验揭示了一个基因间茎环结构作为候选的 mRNA 元件。这是细菌中第一个报道的转录后铜响应机制。