Editor: Klaus Hantke
Characterization of fig operon mutants of Francisella novicida U112
Article first published online: 28 JUN 2008
© 2008 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 285, Issue 2, pages 270–277, August 2008
How to Cite
Kiss, K., Liu, W., Huntley, J. F., Norgard, M. V. and Hansen, E. J. (2008), Characterization of fig operon mutants of Francisella novicida U112. FEMS Microbiology Letters, 285: 270–277. doi: 10.1111/j.1574-6968.2008.01237.x
- Issue published online: 14 JUL 2008
- Article first published online: 28 JUN 2008
- Received 6 February 2008; accepted 20 May 2008.First published online 18 June 2008.
Francisella species secrete a polycarboxylate siderophore that resembles rhizoferrin to acquire ferric iron. Several of the Francisella siderophore synthesis genes are contained in a Fur-regulated operon (designated fig or fsl) comprised of at least seven ORFs including fur. Reverse transcriptase-PCR showed transcriptional linkage between figD and figE and between figE and figF. Mutations were constructed in four of these ORFs (figB, figC, figD, and figE) in Francisella novicida U112. All four of these new mutants and a F. novicida figA mutant grew at rates comparable to that of wild type under iron-replete conditions but growth of all five mutants was stunted in iron-limiting media. When ferric rhizoferrin was added to the iron-limited media, growth of the figA, figB, figC, and figD mutants was restored to levels similar to those obtained in iron-replete media. However, this exogenously added siderophore could not rescue the figE mutant. When Chrome Azurol S assays were used to measure siderophore production, the figA, figB, and figC mutants were markedly deficient in their ability to synthesize siderophore whereas the figD and figE mutants produced siderophore at levels equivalent to the wild-type parent strain.