FIG. 4.

C signal dependence of mutant Ω4400 promoter regions: developmental lacZ expression of pDY70 (A) or pDY30 (B), integrated at attB of wild-type DK1622 (⧫) or csgA mutant DK5208 in the absence (◊) or in the presence (▴) of an equal number of DK1622 cells (lacking lacZ but capable of C signaling). The average β-galactosidase activity of at least three independent isolates is expressed in nanomoles of o-nitrophenyl phosphate per minute per milligram of protein. The error bars indicate one standard deviation. Single isolates with pJB40030 (wild-type Ω4400 promoter from −101 to 155 bp) (▪) or pREG1727 (vector without insert) (•) integrated at attB were included as controls.