FIG. 1.

Introduction of the mutated fimA promoter into P. gingivalis chromosomal DNA. Two genomic configurations can occur after a single crossover between plasmid MPF35 MPF150, or MPS10 and chromosomal DNA. In configuration 1, the crossover occurs upstream of the mutation. In configuration 2, the recombination occurs downstream of the mutation. Pmut. and Pwild represent the mutated and wild-type fimA promoter, respectively; ermF is an erythromycin resistance gene. Configuration 2 was selected by examination by PCR with primer pairs designed for Pmut. and fimA and for Pwild and lacZ.