Table 1.

Complementation of the plc pfoA mutant JIR4444a

StrainGenotypePlasmid-encoded toxin gene(s)Perfringolysin O level (log2 titer)Mean alpha-toxin level ± SD (U/mg of protein [102])
JIR325RifrNalr7.2 ± 0.51.97 ± 0.20
JIR4069JIR325 ΔpfoA::ermB<10.61 ± 0.11
JIR4444JIR4069plcΩpJIR1774<1<0.09 ± 0.01
JIR4459JIR4444(pJIR750)<1<0.09 ± 0.01
JIR4460JIR4444(pJIR871)pfoA+6.7 ± 0.3<0.10 ± 0.01
JIR4461JIR4444(pJIR1642)plc+<10.60 ± 0.17
JIR4462JIR4444(pJIR1720)pfoA+plc+6.7 ± 0.31.90 ± 0.06
  • a Perfringolysin O and phospholipase C assays were performed as previously described (3). The protein concentration was determined by using a microtiter plate protocol from the BCA Protein Assay Reagent Kit (Pierce), with bovine serum albumin as the standard. The results represent the average of duplicate assays carried out on preparations from three separate cultures of each strain.