Czeczulin J R, Collie R E, McClane B A
Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, Pennsylvania 15261, USA.
Infect Immun. 1996 Aug;64(8):3301-9. doi: 10.1128/iai.64.8.3301-3309.1996.
Clostridium perfringens enterotoxin (CPE), the virulence factor responsible for symptoms associated with C. perfringens type A food poisoning, is produced by enterotoxigenic C. perfringens type A isolates when these bacteria sporulate in the gastrointestinal tract. Less than 5% of the global C. perfringens population apparently carries the cpe gene. To assess the distribution of cpe-regulatory factors, we investigated whether the cpe gene of a C. perfringens food poisoning isolate can be expressed and properly regulated (i.e., expressed in a sporulation-associated manner) when transformed into naturally cpe-negative C. perfringens isolates. Sporulation-associated CPE expression was observed when low-copy-number plasmids carrying either a 5.7-kb DNA insert, containing the cpe open reading frame plus >1 kb each of upstream and downstream flanking sequences from C. perfringens food poisoning isolate NCTC 8239, or a 1.6-kb insert, containing only the cpe open reading frame of NCTC 8239, were electroporated into cpe-negative C. perfringens type A, B, and C isolates. Northern (RNA) blot analysis demonstrated that the sizes of the cpe message in the transformants and the naturally enterotoxigenic C. perfringens NCTC 8239 were similar and that this message was detectable only in sporulating cultures of the transformants or NCTC 8239. These studies strongly suggest that many, if not all, cpe-negative C. perfringens isolates (including type B isolates, which are not known to naturally express CPE) produce a factor(s) involved in normal (i.e., sporulation-associated) transcriptional regulation of CPE expression by C. perfringens food poisoning isolates. These findings are consistent with this CPE-regulatory factor(s) also regulating the expression of other genes in C. perfringens.
产气荚膜梭菌肠毒素（CPE）是导致A型产气荚膜梭菌食物中毒相关症状的毒力因子，当产肠毒素A型产气荚膜梭菌在胃肠道中形成芽孢时产生该毒素。全球产气荚膜梭菌群体中显然不到5%携带cpe基因。为了评估cpe调控因子的分布情况，我们研究了产气荚膜梭菌食物中毒分离株的cpe基因在转化为天然cpe阴性的产气荚膜梭菌分离株后，是否能够表达并得到适当调控（即以与芽孢形成相关的方式表达）。当携带5.7 kb DNA插入片段（包含cpe开放阅读框以及来自产气荚膜梭菌食物中毒分离株NCTC 8239的上下游侧翼序列各>1 kb）或1.6 kb插入片段（仅包含NCTC 8239的cpe开放阅读框）的低拷贝数质粒电穿孔导入cpe阴性的A型、B型和C型产气荚膜梭菌分离株时，观察到了与芽孢形成相关的CPE表达。Northern（RNA）印迹分析表明，转化体和天然产肠毒素产气荚膜梭菌NCTC 8239中cpe信息的大小相似，并且该信息仅在转化体或NCTC 8239的芽孢形成培养物中可检测到。这些研究有力地表明，许多（如果不是全部）cpe阴性的产气荚膜梭菌分离株（包括未知天然表达CPE的B型分离株）产生一种因子或多种因子，参与产气荚膜梭菌食物中毒分离株对CPE表达的正常（即与芽孢形成相关的）转录调控。这些发现与这种CPE调控因子也调节产气荚膜梭菌中其他基因的表达一致。
