FIG. 1.

Genetic map of the hrtAB-chrSA loci in C. diphtheriae and in related organisms. A genetic map of the S. aureus hrtAB-hssRS region is also shown for comparison (40). The percentages of amino acid similarity/identity to the C. diphtheriae HrtA and HrtB proteins are indicated below the gene designations. Genes with homology to hrtA are indicated by gray arrows, and homologs of hrtB are shown with hatched arrows. P indicates the locations of known promoters in C. diphtheriae and the directions of transcription. Genes encoding proteins with homology to sensor kinases are indicated in black, and response regulator homologs are shown with open arrows.