Czeczulin J R, Hanna P C, McClane B A
Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261-2072.
Infect Immun. 1993 Aug;61(8):3429-39. doi: 10.1128/iai.61.8.3429-3439.1993.
A complete copy of the gene (cpe) encoding Clostridium perfringens enterotoxin (CPE), an important virulence factor involved in C. perfringens food poisoning and other gastrointestinal illnesses, has been cloned, sequenced, and expressed in Escherichia coli. The cpe gene was shown to encode a 319-amino-acid polypeptide with a deduced molecular weight of 35,317. There was no consensus sequence for a typical signal peptide present in the 5' region of cpe. Cell lysates from recombinant cpe-positive E. coli were shown by quantitative immunoblot analysis to contain moderate amounts of CPE, and this recombinant CPE was equal to native CPE in cytotoxicity for mammalian Vero cells. CPE expression in recombinant E. coli appeared to be largely driven from a clostridial promoter. Immunoblot analysis also demonstrated very low levels of CPE in vegetative cell lysates of enterotoxin-positive C. perfringens. However, when the same C. perfringens strain was induced to sporulate, much stronger CPE expression was detected in these sporulating cells than in either vegetative C. perfringens cells or recombinant E. coli. Collectively, these results strongly suggest that sporulation is not essential for cpe expression, but sporulation does facilitate high-level cpe expression.
产气荚膜梭菌肠毒素（CPE）是产气荚膜梭菌食物中毒及其他胃肠道疾病中一种重要的毒力因子，编码该毒素的基因（cpe）的完整拷贝已在大肠杆菌中克隆、测序并表达。cpe基因编码一个含319个氨基酸的多肽，推导分子量为35317。在cpe的5'区域没有典型信号肽的共有序列。通过定量免疫印迹分析表明，重组cpe阳性大肠杆菌的细胞裂解物中含有适量的CPE，并且这种重组CPE对哺乳动物Vero细胞的细胞毒性与天然CPE相当。重组大肠杆菌中CPE的表达似乎主要受梭菌启动子驱动。免疫印迹分析还表明，产肠毒素产气荚膜梭菌营养细胞裂解物中CPE水平极低。然而，当同一产气荚膜梭菌菌株诱导形成芽孢时，在这些芽孢形成细胞中检测到的CPE表达比产气荚膜梭菌营养细胞或重组大肠杆菌中的要强得多。总体而言，这些结果强烈表明，芽孢形成对于cpe表达并非必不可少，但芽孢形成确实有助于cpe的高水平表达。
