The researchers published their findings Nov. 28 in the online edition of the Proceedings of the National Academy of Sciences. Their paper will appear in the Dec. 5 print edition.
Many bacteria, including the benign Escherichia coli in our gut, make small molecules called siderophores that snatch iron from the tissues of their host so that the bacteria can reproduce. Some strains of E. coli produce more than one kind of siderophore, apparently attacking on several fronts to get the iron they need.
The discovery of a similar strategy in anthrax, Bacillus anthracis, suggests that producing more than one siderophore is a general strategy of bad as well as benign bacteria, according to the researchers. To date, however, only the pathogenic forms of E. coli and Bacillus have been found to produce a siderophore not bound by siderocalin; the non-pathogenic forms that produce more than one siderophore base them on the same molecular structure to which siderocalin binds.
Anthrax is a potential bioweapon because it is nearly always fatal when inhaled. Its long-lived spores grow rapidly in the lungs, leading to breathing problems and shock within days. While a vaccine is available, there is no effective treatment.
The bacteria succeed by forming capsules that invade lung cells, then capturing iron in order to reproduce, and finally, manufacturing a toxin that kills the cells and releases thousands of new spores into the bloodstream.
Because the iron-capture stage is critical to growth, it has become a recent focus of attention as a possible drug target. Raymond, who has studied bacterial siderophores that capture iron for 35 years, recently teamed up with Roland Strong of the Seattle cancer center to study siderocalin, a human protein Strong had found that appeared to interfere with the siderophores secreted by anthrax bacteria.
To study the role of this protein, Raymond and UC Berkeley graduate stu
Source:University of California - Berkeley