Molecular cloning and expression in Escherichia coli of the lethal factor gene of Bacillus anthracis.

We have cloned and expressed in Escherichia coli the lethal factor (LF) gene of Bacillus anthracis. At least two of the six LF recombinant plasmids produce full-length LF protein. Transcription of the LF gene in E. coli appears to be under the control of its own B. anthracis promoter. Recombinant LF protein produced in E. coli remains intracellular and is not secreted. However, this LF protein is biochemically active and displays the same lethal effects as LF secreted by B. anthracis in the mouse macrophage assay. The LF gene, like that of the protective antigen gene, is present on the large B. anthracis toxin plasmid pXO1.