Fig. 2.

Usage of ferrous iron within L. monocytogenes cells. Fe²⁺ ions are primarily used in biological processes, either directly or as a component of haem or iron–sulphur clusters, which act as cofactors of many proteins. Proteins involved in the biosynthesis of haem and Fe–S clusters are given in parentheses. Physiological processes involving iron are given along with examples of engaged proteins. Fe²⁺ ions may also be stored in the single iron storage protein of L. monocytogenes, i.e. the ferritin-like protein Fri. Furthermore, Fe²⁺ ions can form complexes with the Fur regulator participating in this way indirectly in the regulation of the expression of genes involved in the transport and metabolism of iron