Laoide B M, Ullmann A
Unité de Biochimie des Régulations Cellulaires, Institut Pasteur, Paris, France.
EMBO J. 1990 Apr;9(4):999-1005. doi: 10.1002/j.1460-2075.1990.tb08202.x.
The Bordetella pertussis adenylate cyclase (cya) operon is composed of four open reading frames, cyaA, B, D and E (Glaser et al., 1988, EMBO J., 7, 3997-4004). The cyaA gene encodes a virulence factor, cyclolysin, a bifunctional protein exhibiting both adenylate cyclase and haemolytic activities while the cyaB, D and E gene products are necessary for cyclolysin transport. We show that the cyaA gene is activated by a promoter located 115 bp upstream from the translational start codon and that transcription is only activated in virulent strains. Termination of transcription occurs 3' to the cyaA structural gene, however there appears to be some read-through into the downstream genes, resulting in full length cyaABDE transcripts. We also identify a second start site of transcription 30 bp upstream from the cyaB gene, in the intergenic cyaA--cyaB region. Transcription is activated from this site in both Vir+ and Vir- strains. Thus, the expression of the virulence associated cyclolysin is positively controlled via a trans-acting protein encoded by the bvg locus while the transport genes show a lower level of constitutive expression which is independent of virulence control.
百日咳博德特氏菌腺苷酸环化酶（cya）操纵子由四个开放阅读框cyaA、B、D和E组成（Glaser等人，1988年，《欧洲分子生物学组织杂志》，7，3997 - 4004）。cyaA基因编码一种毒力因子——环溶血素，这是一种具有腺苷酸环化酶和溶血活性的双功能蛋白，而cyaB、D和E基因产物是环溶血素运输所必需的。我们发现cyaA基因由位于翻译起始密码子上游115 bp处的启动子激活，并且转录仅在有毒力的菌株中被激活。转录在cyaA结构基因的3'端终止，然而似乎有一些通读进入下游基因，产生全长的cyaABDE转录本。我们还在基因间的cyaA - cyaB区域中，于cyaB基因上游30 bp处鉴定出第二个转录起始位点。在有毒力（Vir +）和无毒力（Vir -）的菌株中，转录均从该位点被激活。因此，与毒力相关的环溶血素的表达通过由bvg位点编码的反式作用蛋白受到正调控，而运输基因显示出较低水平的组成型表达，这与毒力调控无关。
