FIG 6.

Model for Fur-mediated, innate, antinitrosative defenses. Fur-mediated regulation of terminal quinol oxidases of the electron transport chain can boost the innate antinitrosative defenses of Salmonella by (i) generating the ATP that is necessary for bacterial growth and (ii) directly detoxifying NO. The critical role played by Fur in iron homeostasis may also add to the defense mechanisms against nitrosative stress. For example, Fur-regulated expression of the sufABCDSE system could help repair [4Fe-4S] clusters damaged by NO and its oxidative congeners. Moreover, the Fur-dependent control of the labile iron pool could limit the formation of cytotoxic dinitrosyl-iron complexes (DNIC).