Iron regulator 7 protein

Figure 15.19 Regulation of the aconitase/iron-regulating protein balance. A low iron concentration increases the amount of the iron-regulating protein, the role of which is to regulate the iron concentration in the cell. A high iron concentration lowers the amount of the iron-regulating protein and increases that of aconitase.

Abboud, S., and Haile, D. J. (2000). A novel mammalian iron-regulated protein involved in intracellular iron metabolism./. Biol. Chem. 275, 19906-9912. 

CuZn-SOD is an iron-regulated protein in Aspergillus nidulans and A.fumigatus (Oberegger et al. 2000). After 24 h growth under iron deplete conditions, this 16-kDA protein was approximately 5-fold upregulated. 

Lactoferrin j Iron-binding protein May inhibit growth of certain bacteria by binding iron and may be involved in regulation of proliferation of myeloid cells... 

The Fur protein from E. coli was isolated in one step due to its high affinity for metal-chelate columns loaded with zinc. In DNase footprinting experiments, the Fur protein was shown to bind DNA in the promoter region of several iron-regulated genes. The consensus sequence, called the Fur box, is GATAATGATAATCATT ATC. In vitro binding is dependent on the divalent cations Co2+ Mn2+ /s Cd2+ Cu2+ at 150 iM, while Fe2+ seemed to be less active at this concentration, probably due to oxidation to Fe3+ (De Lorenzo et al., 1987). The unspecificity for divalent metals observed in vitro shows that the cells have to select the ions transported carefully and have to balance their active concentrations. In addition, it is a caveat for the experimenter to test a hypothesis on metal-ion specificity not only in vitro, but also in vivo. 

Genes regulated by Fur code for proteins that function in iron transport and iron metabolism under aerobic conditions, iron metabolism is associated with oxidative stress. In addition, some virulence factors are regulated by Fur. Table 3.2 lists examples and functions of Fur- and iron-regulated genes in E. coli, including pathogenic E. coli strains. 

Mazmanian, S. K., Ton-That, H., Su, K. and Schneewind, O. (2002). An iron-regulated sortase anchors a class of surface protein during Staphylococcus aureus pathogenesis, Proc. Natl Acad. Sci. USA, 99, 2293-2298. 

Fur is itself part of the family of gene regulatory proteins throughout many bacterial species. The major subclass is mainly involved, like Fur in E. coli, in the control of iron homeostasis, but it can also function in acid tolerance and protection against oxidative stress. Fur also controls the iron-regulated expression of bacterial virulence determinants. One class of the Fur family, Zur, is involved in the regulation of zinc uptake (see below). 

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