Vodkin M H, Leppla S H
Cell. 1983 Sep;34(2):693-7. doi: 10.1016/0092-8674(83)90402-6.
The tripartite protein toxin of Bacillus anthracis consists of protective antigen (PA), edema factor (EF), and lethal factor (LF). As a first step in developing a more efficacious anthrax vaccine, recombinant plasmids containing the PA gene have been isolated. A library was constructed in the E. coli vector pBR322 from Bam HI-generated fragments of the anthrax plasmid, pBA1. Two clones producing PA were identified by screening lysates with ELISA (enzyme-linked immunosorbent assay). Western blots revealed a full-size PA protein in the recombinant E. coli, and a cell elongation assay demonstrated biological activity. Both positive clones had a 6 kb insert of DNA, which mapped in the Bam HI site of the vector. The two inserts are the same except that they lie in opposite orientations with respect to the vector. Thus PA is encoded by the plasmid pBA1.
炭疽芽孢杆菌的三方蛋白毒素由保护性抗原（PA）、水肿因子（EF）和致死因子（LF）组成。作为开发更有效炭疽疫苗的第一步，已分离出含有PA基因的重组质粒。从炭疽质粒pBA1的Bam HI酶切片段构建了一个大肠杆菌载体pBR322文库。通过用酶联免疫吸附测定（ELISA）筛选裂解物，鉴定出两个产生PA的克隆。蛋白质免疫印迹显示重组大肠杆菌中存在全长PA蛋白，细胞伸长试验证明其具有生物活性。两个阳性克隆都有一个6 kb的DNA插入片段，该片段位于载体的Bam HI位点。除了它们相对于载体的方向相反外，这两个插入片段是相同的。因此，PA由质粒pBA1编码。
