The word siderophore originates from Greek and means iron carrier. Siderophores are low molecular weight substances that have very high affinity for iron (Fe3+) and they bind iron by so-called chelation. Iron is essential for almost all forms of life, because it is a necessary component in the respiratory chain and for DNA synthesis. Many bacteria can secrete siderophores, which allows them to absorb iron even in an environment where the concentration of free iron is very low. The bacterium can then take up the iron, since it has receptors for siderophores in its surface. In mammals, iron is tightly bound to various proteins (e.g. ferritin, lactoferrin, hemoglobin and transferrin) and therefore, pathogenic bacteria bind iron in the form of soluble complexes with siderophores. Siderophores are considered as virulence factors and about 300 different siderophores from various bacteria had been described by year 2015.
Examples of siderophores
See also individual bacterial pages for more examples.