FIG. 1.

Mutational analysis of the C box centered at −49 bp in the Ω4400 promoter region and comparison with the Ω4403 promoter region. (A) Developmental lacZ expression was determined for three independent isolates for each strain. Symbols: ▪, Ω4400 wild-type promoter (−101 to 155 bp), which served as a positive control; •, vector without insert negative control; ▴, T-to-C single-base-pair change at −50 bp; ⧫, C-to-A single-base-pair change at −49 bp. The average β-galactosidase activity is expressed in nanomoles of o-nitrophenyl phosphate per minute per milligram of protein. The error bars indicate one standard deviation. (B) Summary of the effects of transversion mutations at each base pair of the C box centered at −49 bp in both the Ω4400 (solid bars) and Ω4403 (gray bars) promoter regions. The bars indicate the average maximum β-galactosidase specific activity during a 48-h time course, expressed as a percentage of the maximum value observed for the corresponding wild-type promoter. The error bars indicate one standard deviation for data taken from Table 2 and published previously (53).