The authors declare no competing financial interests.
A novel iron- and copper-binding protein in the Lyme disease spirochaete
Article first published online: 1 NOV 2012
© 2012 Blackwell Publishing Ltd
Volume 86, Issue 6, pages 1441–1451, December 2012
How to Cite
Wang, P., Lutton, A., Olesik, J., Vali, H. and Li, X. (2012), A novel iron- and copper-binding protein in the Lyme disease spirochaete. Molecular Microbiology, 86: 1441–1451. doi: 10.1111/mmi.12068
- Issue published online: 13 DEC 2012
- Article first published online: 1 NOV 2012
- Accepted manuscript online: 14 OCT 2012 11:28PM EST
- Manuscript Accepted: 9 OCT 2012
- Arthritis Investigator Award from the Arthritis Foundation
- Public Health Preparedness for Infectious Diseases Program
- College of Veterinary Medicine of the Ohio State University
Iron and copper are transition metals that can be toxic to cells due to their abilities to react with peroxide to generate hydroxyl radical. Ferritins and metallothioneins are known to sequester intracellular iron and copper respectively. The Lyme disease pathogen Borrelia burgdorferi does not require iron, but its genome encodes a ferritin-like Dps (DNA-binding protein from starved bacteria) molecule, which has been shown to be important for the spirochaete's persistence in the tick and subsequent transmission to a new host. Here, we show that the carboxyl-terminal cysteine-rich (CCR) domain of this protein functions as a copper-binding metallothionein. This novel fusion between Dps and metallothionein is unique to and conserved in all Borrelia species. We term this molecule BicA for Borrelia iron- and copper-binding protein A. An isogenic mutant lacking BicA had significantly reduced levels of iron and copper and was more sensitive to iron and copper toxicity than its parental strain. Supplementation of the medium with iron or copper rendered the spirochaete more susceptible to peroxide killing. These data suggest that an important function of BicA is to detoxify excess iron and copper the spirochaete may encounter during its natural life cycle through a tick vector and a vertebrate host.