FIG. 4.

Identification of poxA gene product by using the T7 expression system. poxA was cloned in both orientations under the control of the bacteriophage T7 promoter in the vector pKSII and introduced into E. coli BL21(DE3), which carries a bacteriophage T7 RNA polymerase gene under the control of the lac promoter. After induction, whole-cell lysate proteins were separated on an SDS-polyacrylamide gel as described in Materials and Methods. Numbers on the left indicate the positions of molecular mass standards (in kilodaltons). The arrow indicates a polypeptide of about 36 kDa specifically encoded by pMEG-251, the putative gene product of poxA. pMEG-251, poxA under the T7 promoter; pMEG-273, poxA in opposite orientation from the T7 promoter; pKSII, vector control.