Di-iron proteins of the Ric family are involved in iron-sulfur cluster repair.

A key element in eukaryotic immune defenses against invading microbes is the production of reactive oxygen and nitrogen species. One of the main targets of these species are the iron-sulfur clusters, which are essential prosthetic groups that confer to proteins the ability to perform crucial roles in biological processes. Microbes have developed sophisticated systems to eliminate nitrosative and oxidative species and promote the repair of the damages inflicted. The Ric (Repair of Iron Centers) proteins constitute a novel family of microbial di-iron proteins with a widespread distribution among microbes, including Gram-positive and Gram-negative bacteria, protozoa and fungi. The Ric proteins are encoded by genes that are up-regulated by nitric oxide and hydrogen peroxide. Recent studies have shown that the active di-iron center is involved in the restoration of Fe-S clusters damaged by exposure to nitric oxide and hydrogen peroxide.