Saint-Joanis B, Garnier T, Cole S T
Laboratoire de Génétique Moléculaire Bactérienne, Institut Pasteur, Paris, France.
Mol Gen Genet. 1989 Nov;219(3):453-60. doi: 10.1007/BF00259619.
The plc gene encoding the alpha-toxin (phospholipase C), an important virulence factor of Clostridium perfringens, has been cloned, sequenced and expressed in Escherichia coli. Transcriptional analysis of mRNAs produced in vivo by C. perfringens and E. coli, and in vitro using purified RNA polymerase from C. perfringens revealed that plc is transcribed constitutively from a single promoter situated about 100 nucleotides from the coding sequence. A T7 expression system was used to overproduce alpha-toxin in E. coli; enzymological studies with the amplified plc gene product unambiguously demonstrated that both lecithinase (phospholipase C) and sphingomyelinase activities were associated with this 43,000 dalton cytotoxin. The 370-residue alpha-toxin is haemolytic and shares sequence and functional homology with the two components of Bacillus cereus haemolysin, cereolysin AB, in which phospholipase C and sphingomyelinase activities are associated with different polypeptides.
编码产气荚膜梭菌重要毒力因子α毒素（磷脂酶C）的plc基因已在大肠杆菌中克隆、测序并表达。对产气荚膜梭菌和大肠杆菌体内产生的mRNA以及使用产气荚膜梭菌纯化的RNA聚合酶在体外进行的转录分析表明，plc是从位于编码序列约100个核苷酸处的单个启动子组成型转录的。使用T7表达系统在大肠杆菌中过量表达α毒素；对扩增的plc基因产物进行的酶学研究明确表明，卵磷脂酶（磷脂酶C）和鞘磷脂酶活性均与这种43000道尔顿的细胞毒素相关。370个氨基酸残基的α毒素具有溶血作用，并且与蜡样芽孢杆菌溶血素cereolysin AB的两个组分在序列和功能上具有同源性，其中磷脂酶C和鞘磷脂酶活性与不同的多肽相关。
