Analysis of Virulence-Associated Petrobactin Reacquisition in Bacillus anthracis.

Abstract

In Bacillus anthracis the siderophore petrobactin is vital for iron acquisition and virulence. The petrobactin-binding receptor FpuA is required for these processes. FpuA has high homology to the receptors associated with ATP-binding Cassette (ABC) transporter complexes, indicating that the mechanism of petrobactin reacquisition requires an ABC transport system. ABC transporters are used by bacteria for cross-membrane transport of many small molecules. Recently, the additional components of petrobactin reacquisition have been identified. We have shown that either of two distinct permeases, FpuB or FatCD, are required for iron acquisition and play redundant roles in petrobactin transport. Additionally, three ATPase proteins are sufficient to provide the energy required for petrobactin reacquisition. These results provide the first description of the permease and ATPase proteins required for the import of petrobactin in B. anthracis. Furthermore, these ABC-transport proteins are essential in cell viability, virulence and pathogenicity. The ABC ATPases share conserved sequences across all bacterial species, and only requires ATP as a substrate, making these proteins prime candidates for a high-throughput inhibitor search for small molecules that can potentially block siderophore import and thus the necessary act of iron acquisition by B. anthracis and other dangerous pathogens. Sixteen top ATPase inhibitor hits were identified in a pilot high-throughput screen at the University of Michigan Center for Chemical Genomics. Eight of which were reconfirmed at the bench-top to reveal three compounds as promising leads in the development of therapeutics or tools to probe ATPase activity.PhDMicrobiology & ImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/97997/1/shandeed_1.pd