Gross R, Rappuoli R
Sclavo Research Center, Siena, Italy.
Proc Natl Acad Sci U S A. 1988 Jun;85(11):3913-7. doi: 10.1073/pnas.85.11.3913.
Although the genus Bordetella contains several closely related species, pertussis toxin (PT) is produced only by phase I Bordetella pertussis. In this work we have studied the regulation of expression of the PT operon and investigated why PT is produced by phase I and not by phase III B. pertussis despite the presence of the PT genes. We have constructed a vector for Bordetella species that contains the PT promoter fused to the coding region of the chloramphenicol acetyltransferase (CAT) gene, and we have used it to identify the regulatory elements involved in the transcription of the PT operon. Efficient transcription of these genes requires at least two features: (i) the 170-base-pair DNA sequence upstream from the start site of transcription and (ii) a trans-activating factor encoded by the vir locus. Bordetella parapertussis and Bordetella bronchiseptica, although endowed with a functional trans-activating system, do not produce PT because of mutations within their PT promoter regions. In contrast, phase III Bordetella species do not show any trans activity.
尽管博德特氏菌属包含几个密切相关的种，但百日咳毒素（PT）仅由I相百日咳博德特氏菌产生。在本研究中，我们研究了PT操纵子表达的调控，并探讨了为什么尽管存在PT基因，PT却由I相而非III相百日咳博德特氏菌产生。我们构建了一种用于博德特氏菌属的载体，该载体包含与氯霉素乙酰转移酶（CAT）基因编码区融合的PT启动子，并用它来鉴定参与PT操纵子转录的调控元件。这些基因的有效转录至少需要两个特征：（i）转录起始位点上游170个碱基对的DNA序列和（ii）由vir位点编码的反式激活因子。副百日咳博德特氏菌和支气管败血博德特氏菌虽然具有功能性的反式激活系统，但由于其PT启动子区域内的突变而不产生PT。相反，III相博德特氏菌属没有任何反式活性。
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