WalRK two component system of Bacillus anthracis responds to temperature and antibiotic stress

•Bacillus anthracis WalRK forms an operon with six other genes.•WalRK functional promoter lies within 317 bp region upstream of WalR start codon.•Maximal WalRK promoter activity was observed during early growth phases.•WalRK expression is upregulated during temperature and antibiotic stress.•WalR overexpression did not affect the tested antibiotic MIC values in B. anthracis.

WalRK Two Component System (TCS) of Bacillus anthracis forms a functional TCS. This report elaborates upon the WalRK genomic architecture, promoter structure, promoter activity and expression under various stress conditions in B. anthracis. 5′ RACE located the WalRK functional promoter within 317 bp region upstream of WalR. Reporter gene assays demonstrated maximal promoter activity during early growth phases indicating utility in exponential stages of growth. qRT-PCR showed upregulation of WalRK transcripts during temperature and antibiotic stress. However, WalR overexpression did not affect the tested antibiotic MIC values in B. anthracis. Collectively, these results confirm that WalRK responds to cell envelope stress in B. anthracis.