Diagram of a series of dbpBA promoter (PdbpBA)-luc reporter constructs (A) and different constructs containing various versions of PdbpBA with the entire dbpBA operon to complement dbpBA expression in trans in the dbpBA deletion strain BbKH500 (B). Nucleotide positions are relative to the ATG start codon, where A is +1. WT, wild-type PdbpBA; ΔIR1, deletion of IR1; ΔIR1/2, deletion of both IR1 and IR2; Min, minimal PdbpBA; Min C/A, minimal PdbpBA with the −14 C mutated to A; Δ−35, deletion of −35 sequence; Δ−35/−10, deletion of both −35 sequence and −10 sequence.