FIG 2.

Schematic diagram showing plasmid constructs used for heterologous expression of tpeE and tpeL in C. perfringens strain HN13. pKRAH1 has a lactose-inducible promoter for regulated expression (31), which is indicated by arrows. ΔHCD, deletion of the high charge density domain at the C terminus; ΔAPH, deletion of the amphipathic helix. TpeLA, TpeLAC, and TpeLACD are constructs with deletions of nested C-terminal domains of full-length TpeL. All constructs have a SacII site at the 5′ end and a BamHI site at the 3′ end of the inserts. Some, indicated with an asterisk, have an additional SalI site inserted between the tpeE and tpeL genes to allow efficient cloning. Each plasmid and its description are also listed in Table 1.