Iron metabolism in pathogenic bacteria

The ability of pathogens to obtain iron from transferrins, ferritin, hemogl obin, and other iron-containing proteins of their host is central to whethe r they live or die. To combat invading bacteria, animals go into an iron-wi thholding mode and also use a protein (Nramp1) to generate reactive oxygen species in an attempt to kill the pathogens. Some invading bacteria respond by producing specific iron chelators-siderophores-that remove the iron fro m the host sources. Other bacteria rely on direct contact with host iron pr oteins, either abstracting the iron at their surface or, as with heme, taki ngs it up into the cytoplasm. The expression of a large number of genes (>4 0 in some cases) is directly controlled by the prevailing intracellular con centration of Fe(II) via its complexing to a regulatory protein (the Fur pr otein or equivalent). Tn this way, the biochemistry of the bacterial cell c an accommodate the challenges from the host. Agents that interfere with bac terial iron metabolism may prove extremely valuable for chemotherapy of dis eases.