Effect of ipa operon promoter deletions on IpaB expression. (A) Whole-cell proteins of E. coli CC118 harboring the parent plasmid pHW1273 (lane 7) or its derivatives pTT0818 (lane 1), pTT1405 (lane 2), pTT1608 (lane 3), pTT1804 (lane 4), pTT2002 (lane 5), and pTT0606 (lane 6) were separated in a 12% polyacrylamide gel, immunoblotted, and detected with antiserum specific to IpaB. (B) Schematic diagram of pTT1608, pTT2201, pTT2202, and pTT2203 around the ParB BoxA-like sequence. At the top of this figure, the solid arrow indicates the direction of ipa operon transcription. The DNA sequence indicates the −88 to −74 region (icsB transcription start site as nucleotide +1), and the box indicates the position of the ParB BoxA-like sequence. Under the DNA sequence, thick horizontal lines indicate the predicted promoter region of the ipa operon in the derivatives, and horizontal dotted lines indicate the deleted regions. (C) Whole-cell proteins of E. coli CC118 harboring the parent plasmid pHW1273 (lane 5) or its derivatives pTT1608 (lane 1), pTT2201 (lane 2), pTT2202 (lane 3), and pTT2203 (lane 4) were separated in a 12% polyacrylamide gel, immunoblotted, and detected with antiserum specific to IpaB.