FIG. 4.

Expression of txeR in C. difficile. (A) Derivatives of C. difficile strain CD37 carrying a plasmid-borne PtxeR-gusA fusion (with or without the txeR gene) were grown in either TY or TYG medium, and β-glucuronidase activity was determined as described in Materials and Methods. The arrows indicate the times at which the cultures left the rapid-exponential-growth phase. (B) Western blot of TxeR protein in C. difficile. Crude extracts of late-stationary-phase cells of C. difficile strain VPI10463 grown in either TYG (lane 1) or TY (lane 2) medium were analyzed by immunoblotting with anti-TxeR antibody as described in Materials and Methods. The arrow shows the position of TxeR.