The AtxA virulence regulator of Bacillus anthracis is required for toxin and 
capsule gene expression. AtxA is a phosphotransferase system regulatory 
domain-containing protein whose activity is regulated by 
phosphorylation/dephosphorylation of conserved histidine residues. Here we 
report that transcription of the atxA gene occurs from two independent 
promoters, P1 (previously described by Dai et al. [Z. Dai, J. C. Sirard, M. 
Mock, and T. M. Koehler, Mol. Microbiol. 16:1171-1181, 1995]) and P2, whose 
transcription start sites are separated by 650 bp. Both promoters have -10 and 
-35 consensus sequences compatible with recognition by sigma(A)-containing RNA 
polymerase, and neither promoter depends on the sporulation sigma factor SigH. 
The dual promoter activity and the extended untranslated mRNA suggest that 
as-yet-unknown regulatory mechanisms may act on this region to influence the 
level of AtxA in the cell.