FIG. 1.

Functional and genetic maps of the ahpCF locus in B. fragilis strains. (A) Wild-type gene in strains 638R (wild type) and IB263 (hpr). The striped and grey arrows represent the ahpC and ahpF genes, respectively; The letter P and a dark arrowhead mark the promoter region and the transcription start site. Arrows under the map represent the length and orientation of the transcripts. Also shown are the ahpC and ahpF double-stranded dsDNA fragments used as probes for Northern blot hybridizations. (B to D) Schematic representations of the single-crossover insertional disruptions of the ahpC and ahpF genes and the ahpC′::XA construct in the chromosome. A partial restriction map is shown above the diagrams. The twisted line is not drawn to scale and represents the suicide vector pFD516 (7.7 kb). The bifunctional XA reporter gene is depicted as the hatched arrow.