top – ACO1; bottom – iron regulatory protein 1 bound to an mRNA
Iron metabolism is regulated by hepicidin, ferroportin and iron regulatory proteins. Aconitase 1 (ACO1) is a dual function protein that serves as an aconitase, which is an enzyme in the TCA cycle, when ACO1 has a 4Fe-4S iron sulfur cluster and as iron regulatory protein 1 when ACO1 looses a 4Fe-4S cluster. The sulfur for iron-sulfur clusters is derived from L-cysteine.
L-cysteine is synthesized from homocyteine via the transsulfuration pathway. Dysregulation of the transsufuration pathway by dysregulating L-cysteine synthesis could dysregulate iron-sulfur cluster formation thereby dyseregulating iron regulatory protein 1 and iron homestasis.
High homocysteine levels are present in a lot of illnesses, for example, schizophrenia, Parkinson’s disease, Alzheimer’s disease and bipolar disorder. A key part of the difficulties that arise from high homocysteine levels could be due to dysregulation of iron homeostasis.