Biological trivalent metal selectivity in a bacterial transferrin: Gallium-FbpA thermodynamics and kinetics

INOR 886

Jared J. Heymann, heymann@chem.duke.edu1, Katherine D. Weaver, k.weaver@duke.edu1, D. S. Anderson2, T. A. Mietzner2, and A. L. Crumbliss, alc@chem.duke.edu1. (1) Department of Chemistry, Duke University, Box 90346, Durham, NC 27708-0346, (2) Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
Ferric binding protein (FbpA) is a bacterial transferrin, functioning as the lone protein responsible for the trans-periplasmic iron transport in certain gram-negative bacteria. In addition to the similarities in structure and function, FbpA, like transferrin, exhibits in vitro specificity for ferric iron over other trivalent metal ions, such as gallium. Gallium is of specific interest both chemically and biologically. The chemistry of gallium is unique as it mimics iron(III) in both charge and size, while lacking the redox ability possessed by iron. Biologically, gallium has been utilized as an iron mimic in a variety of sidero-proteins, with differing consequences for organism health. Recent implications for antibacterial function provide an enhanced interest in microbial-gallium interaction. Here, we report thermodynamic and kinetic data, which support the preference for iron over gallium by FbpA in vitro. A comparison between FbpA and other transferrins is considered, and the extent and biological implications of this selectivity are discussed.
 

General Inorganic Chemistry
1:30 PM-5:20 PM, Wednesday, August 22, 2007 BCEC -- 212, Oral

Division of Inorganic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007