9 bp inverted repeat sequences separated by a single A nucleotide to create a 19 bp palindromic sequence as follows: GATAATGA- TAATCATTATC [33]. This sequence can also be interpreted as a series of three hexameric repeats of NATA/TAT [34]. However, in H. pylori this E. coli Fur Box is not conserved, and consensus is currently ill-defined. For iron-bound Fur regulation, the binding sequence occurs in A/T-rich regions in the target promoter oftentimes with repeats of AAT [8,24,25,35,36]. There is no defined consensus sequence for apo-Fur binding given that the two promoters of the known apo-Fur regulated genes, pfr and sodB, share only minimal homology [1,8]. In an organism that has about 60% A/T residues in its genome, a Fur Box consensus sequence that is comprised of mainly these two nucleotides does not seem to be an ideal approach for Fur regulation. 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PLoS ONE | www.plosone.org 12 April 2009 | Volume 4 | Issue 4 | e5369