Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Iron Homeostasis in Brucella abortus: the Role of Bacterioferritin: Marta A. Almirón , Rodolfo A. Ugalde; J. Microbiol. 2010;48(5):668-673. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0145-3

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Abstract: Brucella abortus is the etiological agent of bovine brucellosis, an infectious disease of humans and cattle. Its pathogenesis is mainly based on its ability to survive and multiply inside macrophages. It has been demonstrated that if B. abortus ferrochelatase cannot incorporate iron into protoporphyrin IX to synthesize heme, the intracellular replication and virulence in mice is highly attenuated. Therefore, it can be hypothesized that the unavailability of iron could lead to the same attenuation in B. abortus pathogenicity. Thus, the purpose of this work was to obtain a B. abortus derivative unable to keep an internal iron pool and test its ability to replicate under iron limitation. To achieve this, we searched for iron-storage proteins in the genome of brucellae and found bacterioferritin (Bfr) as the sole ferritin encoded. Then, a B. abortus bfr mutant was built up and its capacity to store iron and replicate under iron limitation was investigated. Results indicated that B. abortus Bfr accounts for 70% of the intracellular iron content. Under iron limitation, the bfr mutant suffered from enhanced iron restriction with respect to wild type according to its growth retardation pattern, enhanced sensitivity to oxidative stress, accelerated production of siderophores, and altered expression of membrane proteins. Nonetheless, the bfr mutant was able to adapt and replicate even inside eukaryotic cells, indicating that B. abortus responds to internal iron starvation before sensing external iron availability. This suggests an active role of Bfr in controlling iron homeostasis through the availability of Bfr-bound iron.

Overexpression of Bacterioferritin Comigratory Protein (Bcp) Enhances Viability and Reduced Glutathione Level in the Fission Yeast Under Stress: Ga-Young Kang , Eun-Hee Park , Kyunghoon Kim , Chang-Jin Lim; J. Microbiol. 2009;47(1):60-67. Published online February 20, 2009; DOI: https://doi.org/10.1007/s12275-008-0077-3

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Abstract: The structural gene encoding bacterioferritin comigratory protein (Bcp) was amplified using PCR from the genomic DNA of Schizosaccharomyces pombe, and transferred into the shuttle vector pRS316 to generate the recombinant plasmid pBCP10. The bcp+ mRNA level in the pBCP10-containing yeast cells was significantly higher than that in the control yeast cells, indicating that the cloned gene is functioning. The S. pombe cells harboring the plasmid pBCP10 exhibited higher survival on the solid minimal media with hydrogen peroxide, tert-BOOH or cadmium than the control yeast cells. They also exhibited enhanced cellular viability in the liquid media containing the stressful agents. The increased viabilities of the fission yeast cells harboring the plasmid pBCP10 were also obtained with 0.4% glucose or 0.4% sucrose as a sole carbon source, and nitrogen starvation, compared with those of the control yeast cells. The total glutathione (GSH) content and total GSH/GSSG ratio were significantly higher in the yeast cells harboring the plasmid pBCP10 than in the control yeast cells. In brief, the S. pombe Bcp plays a protective role in the defensive response to oxidative stress possibly via up-regulation of total and reduced glutathione levels.

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