RT Journal Article SR Electronic(1) A1 Milne, Timothy S. A1 Michell, Stephen L. A1 Diaper, Helen A1 Wikström, Per A1 Svensson, Kerstin A1 Oyston, Petra C. F. A1 Titball, Richard W.YR 2007 T1 A 55 kDa hypothetical membrane protein is an iron-regulated virulence factor of Francisella tularensis subsp. novicida U112 JF Journal of Medical Microbiology, VO 56 IS 10 SP 1268 OP 1276 DO https://doi.org/10.1099/jmm.0.47190-0 PB Microbiology Society, SN 1473-5644, AB Iron is an important nutritional requirement for bacteria due to its conserved role in many essential metabolic processes. As a consequence of the lack of freely available iron in the mammalian host, bacteria upregulate a range of virulence factors during infection. Transcriptional analysis of Francisella tularensis subsp. novicida U112 grown in iron-deficient medium identified 21 genes upregulated in response to this condition, four of which were attributed to a siderophore operon. In addition, a novel iron-regulated gene, FTT0025, was identified which is part of this operon and encodes a 55 kDa hypothetical membrane protein. When grown on chrome azurol S agar, the F. tularensis subsp. novicida U112ΔFTT0025 mutant produced an increased reaction zone compared with the wild-type, suggesting that siderophore production was unaffected but that the bacteria may have a deficiency in their ability to re-sequester this iron-binding molecule. Furthermore, the ΔFTT0025 mutant was attenuated in a BALB/c mouse model of infection relative to wild-type F. tularensis subsp. novicida U112., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.47190-0