Cellular Iron Distribution in Bacillus anthracis (2012)

Author(s): Tu WY, Pohl S, Gray J, Robinson NJ, Harwood CR, Waldron KJ

    Abstract: Although successful iron acquisition by pathogens within a host is a pre-requisite for the establishment of infection, surprisingly little is known about the intracellular distribution of iron within bacterial pathogens. We have used a combination of anaerobic, native liquid chromatography, inductively coupled plasma mass spectrometry, principal component analysis and peptide mass fingerprinting to investigate the cytosolic iron distribution in the pathogen Bacillus anthracis. Our studies identified three of the major iron pools as being associated with the electron transfer protein ferredoxin, the mini-ferritin Dps2 and the superoxide dismutase (SOD) enzymes SodA1 and SodA2. Although both SOD isozymes were predicted to utilize manganese cofactors, quantification of the metal ions associated with SodA1 and SodA2 in cell extracts established that SodA1 is associated with both manganese and iron, whereas SodA2 is bound exclusively to iron in vivo. These data were confirmed by in vitro assays using recombinant protein preparations, showing that SodA2 is active with an iron co-factor, while SodA1 is cambialistic, i.e. active with manganese or iron. Furthermore, we observe that B. anthracis cells exposed to superoxide stress increase their total iron content more than two-fold over 60 minutes, while the manganese and zinc content is unaffected. Notably, the acquired iron is not localized to the three identified cytosolic iron pools.

      • Date: 01-03-2012
      • Journal: Journal of Bacteriology
      • Volume: 194
      • Issue: 5
      • Pages: 932-940
      • Publisher: American Society for Microbiology
      • Publication type: Article
      • Bibliographic status: Published

      Professor Colin Harwood
      Professor of Molecular Microbiology

      Dr Kevin Waldron
      University Research Fellow