Iron biology
Our Genome and Iron
About 2% of human genes encode an iron-protein.
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- 35% are proteins binding individual iron ions
- 48% are heme-binding proteins
- 17% are iron–sulfur proteins
More than half of the human iron-proteins have a
catalytic function.
Proteomic analysis suggests that 6.5% of all human enzymes are iron-dependent.
Most iron is bound up in red blood cells, myoglobin in muscles, energy producing enzymes in mitochondria, and stored in ferratin, an iron binding protein in the liver, spleen and bone marrow. Very little iron, ~0.1%, is circulating freely, yet this is the iron utilized by most pathogens and cancer cells to grow.
The distribution of iron in the body
Body responds to infection by withdrawing iron pathogens need to grow
The body has a natural response to an acute infection, a host-driven iron withdrawal mechanism called the hypoferremic response which inhibits the growth of pathogens. It is characterized by increasing iron storage, shutting off iron export from cells and increasing iron import.
This response is because iron is just as important for other life forms including pathogens like bacteria and fungi. It is perhaps the most important micronutrient required for bacteria to proliferate and cause disease.
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- It is required for many proteins and enzymes involved in a variety of metabolic processes.
- It is essential for expression of many key virulence determinants.
- Without iron, it is almost impossible for bacteria to establish themselves within the host and cause disease.