The alignment of Fur proteins from E.coli, S.typhi, Y.pestis and V.cholerae. Amino acids of the DNA recognition helix are shown in yellow. Lys76, which also might interact directly with DNA, is shown in green.

(A) The chemotaxis system of E.coli (taken from KEGG; 61). (B) One of the three loci containing che genes. The homologs of cheW, cheB, cheR, cheY and cheA are shown by the yellow arrows, genes encoding the MCPs are shown by the light green arrows. (C) The Tcp-encoding locus. The tcp genes similar to MCPs are represented by the light green arrows. All other tcp genes are represented by lilac arrows. The gene for the regulator ToxT is shown by the pink arrow

(A–C) The structure of three homologous iron-acquisition loci of: (A) E.coli, (B) P.aeruginosae and (C) V.cholerae. The gene orf1 homologous to the iron uptake factors of E.coli and P.aeruginosa is missed in the annotation of the full genome of V.cholerae. (D–F) The structure of three siderophores-biosynthesis loci of Y.pestis. (G) The structure of Y.pestis locus that consists of the iron ABC transporter, the outer membrane receptor, the putative transcriptional regulator and the virulence-associated psa system. (H) The structure of the heme-acquisition locus of Y.pestis. (I and J) The structure of two iron-transport systems of (I) V.cholerae and (J) N.meningitis. Genes are shown by arrows, candidate FUR-boxes are shown by yellow circles. Blue arrow, the gene for iron ABC transporter; violet arrow, the gene for outer membrane ferrisiderophore receptor; lilac arrow, the gene for virulence-associated protein; pink arrow, the gene for transcriptional regulator; green arrow, the gene for siderophore-biosynthesis protein; yellow arrow, the gene for iron reductase; grey arrow, the gene for tonB protein; black arrow, other genes.