Bacillus anthracis Virulence Regulator AtxA Binds Specifically to the pagA Promoter Region

Abstract

Anthrax toxin activator (AtxA) regulates the major virulence genes in Bacillus anthracis . The bacterium produces the anthrax toxins, and understanding the mechanism of toxin production may facilitate the development of therapeutics for B. anthracis infection. Since the discovery of AtxA 25 years ago, the mechanism by which it regulates its targets has largely remained a mystery. Here, we provide evidence that AtxA binds to the promoter region of the pagA gene encoding the main central protective antigen (PA) component of the anthrax toxin. These data suggest that AtxA binding plays a direct role in gene regulation. Our work also assists in clarifying the role of CO 2 in AtxA’s gene regulation and provides more evidence for the role of AtxA phosphorylation in virulence gene regulation.