Betsou F, Sebo P, Guiso N
Unité de Bactériologie Moléculaire et Médicale, Institut Pasteur, Paris, France.
Infect Immun. 1993 Sep;61(9):3583-9. doi: 10.1128/iai.61.9.3583-3589.1993.
Bordetella pertussis adenylate cyclase-hemolysin (AC-Hly), encoded by the cyaA gene, belongs to the RTX family of toxins with extensive glycine-rich repeats in the carboxy-terminal portion. AC-Hly possesses both adenylate cyclase toxic and hemolytic activities that depend on a posttranslational modification mediated by the product of the cyaC gene. An improved system for AC-Hly synthesis and activation in Escherichia coli was developed. The results show that with purified AC-Hly (i) increased expression of the cyaC gene leads to a higher proportion of activated AC-Hly, (ii) the increase in protective activity of the activated recombinant AC-Hly correlates with the increase in its invasive and hemolytic activities, and (iii) the activated recombinant AC-Hly, but not the nonactivated recombinant AC-Hly, is a protective antigen against B. pertussis infection in a murine respiratory model. This suggests that possibly an immunodominant epitope required for protective activity is linked to the CyaC-mediated modification. Surprisingly, the protective and hemolytic activities of activated recombinant AC-Hly were lower than those of AC-Hly produced by B. pertussis, while its invasive activity was higher. This indicates that the modification of AC-Hly in B. pertussis and that in E. coli may differ.
百日咳博德特氏菌腺苷酸环化酶-溶血素（AC-Hly）由cyaA基因编码，属于毒素RTX家族，其羧基末端部分有大量富含甘氨酸的重复序列。AC-Hly同时具有腺苷酸环化酶毒性和溶血活性，这两种活性依赖于由cyaC基因产物介导的翻译后修饰。开发了一种在大肠杆菌中合成和激活AC-Hly的改进系统。结果表明，对于纯化的AC-Hly：（i）cyaC基因表达的增加会导致活化的AC-Hly比例更高；（ii）活化的重组AC-Hly的保护活性增加与其侵袭和溶血活性的增加相关；（iii）在小鼠呼吸道模型中，活化的重组AC-Hly而非未活化的重组AC-Hly是抗百日咳博德特氏菌感染的保护性抗原。这表明保护性活性所需的可能一个免疫显性表位与CyaC介导的修饰有关。令人惊讶的是，活化的重组AC-Hly的保护和溶血活性低于百日咳博德特氏菌产生的AC-Hly，而其侵袭活性更高。这表明百日咳博德特氏菌中AC-Hly的修饰与大肠杆菌中的修饰可能不同。
