Regulation of Iron Homeostasis in Bacteria
Pierre Cornelis and Simon C. Andrews
from: Bacterial Regulatory Networks (Edited by: Alain A.M. Filloux). Caister Academic Press, U.K. (2012)
For the vast majority of bacteria, iron is an essential element that is not readily available due to the poor solubility of the oxidized Fe3+ form that prevails aerobically. Because of this, bacteria inhabiting aerobic niches often suffer deficiencies in iron supply. Pathogenic bacteria experience a particularly acute form of iron-restriction. This arises from the host's 'iron-withdrawal response' to infection, whereby iron availability is constrained by increasing lactoferrin (an iron-chelating, bacteriostatic, extracellular glycoprotein) levels and reducing the degree of iron saturation for the circulating iron-transport protein, transferrin. The importance of iron to bacteria stems from its multiple metabolic roles. Examples of its crucial metabolic involvement include redox-stress resistance (e.g. heme-bearing catalases) and DNA manufacture (di-Fe containing ribonucleotide reductases). Although indispensible, iron is an unfriendly, hazardous metal as the Fe2+-triggered Fenton reaction produces destructive reactive oxygen species (ROS) such as superoxide (O2-), hydrogen peroxide (H2O2) as well as the highly reactive hydroxyl radical (˚OH) read more ...