Using these anthrax bacteria extracts, Abergel and Hoette isolated the two siderophores, bacillibactin and petrobactin, and showed that siderocalin tightly binds bacillibactin, preventing it from capturing iron from human cells. However, siderocalin does not prevent petrobactin from binding iron.
Interestingly, bacillibactin is very similar to siderophores in other bacteria, including enterobactin, which is produced by several pathogenic bacteria that live in the gut, such as Salmonella enterica and pathogenic strains of E. coli. These two bacteria also contain a second siderophore, aerobactin, with a molecular structure similar to petrobactin.
The researchers suggest that producing a second, stealth siderophore - petrobactin or aerobactin - that has a different molecular structure than bacillibactin and enterobactin may be a common response by bacteria to the human body's production of siderocalin.
The research could lead to anti-anthrax drugs that target petrobactin synthesis or iron-uptake, or to anthrax sensors that detect petrobactin, which is not known to occur in any other pathogenic bacteria.
Source:University of California - Berkeley