Miller J F, Roy C R, Falkow S
Department of Microbiology and Immunology, Stanford University, California 94305.
J Bacteriol. 1989 Nov;171(11):6345-8. doi: 10.1128/jb.171.11.6345-6348.1989.
The virulence regulon of Bordetella pertussis includes a trans-acting regulatory locus, bvg, that is required for expression of several virulence factors. The virulence control system also responds to environmental signals. We have reconstructed a bvg-dependent regulatory system in Escherichia coli by using bacteriophage lambda vectors carrying transcriptional fusions to lacZYA. Single-copy lacZYA fusions to the B. pertussis fhaB locus, which encodes the attachment factor filamentous hemagglutinin, were activated nearly 400-fold by pBR322 replicons carrying sequences that included bvg. In contrast, bvg had no effect on the pertussis toxin operon (ptxA-E) promoter in E. coli as measured by ptxA-lacZ expression. Environmental signals that modulate expression of virulence genes in B. pertussis had a pronounced effect on bvg-mediated activation of fhaB-lacZ. MgSO4, nicotinic acid, and low temperature resulted in decreases in beta-galactosidase activities of 175-, 115-, and 45-fold respectively. Sensory transduction and transcriptional activation were tightly coupled, and both required an intact bvg locus as determined by 5' and 3' deletions that eliminated both activities.
百日咳博德特氏菌的毒力调节子包含一个反式作用调节位点bvg，它是几种毒力因子表达所必需的。毒力控制系统也对环境信号作出反应。我们通过使用携带与lacZYA转录融合的噬菌体λ载体，在大肠杆菌中重建了一个依赖bvg的调节系统。与编码黏附因子丝状血凝素的百日咳博德特氏菌fhaB基因座的单拷贝lacZYA融合，被携带包含bvg序列的pBR322复制子激活了近400倍。相比之下，通过ptxA-lacZ表达测定，bvg对大肠杆菌中的百日咳毒素操纵子（ptxA-E）启动子没有影响。调节百日咳博德特氏菌中毒力基因表达的环境信号，对bvg介导的fhaB-lacZ激活有显著影响。硫酸镁、烟酸和低温分别导致β-半乳糖苷酶活性降低175倍、115倍和45倍。感觉转导和转录激活紧密耦合，并且两者都需要完整的bvg位点，这是通过消除这两种活性的5'和3'缺失确定的。
