Characterization of Arabidopsis thaliana FRATAXIN HOMOLOG in heme catabolism.

Frataxin plays vital roles in various iron related processes. Arabidopsis thaliana FRATAXIN HOMOLOG (AtFH) is the first identified plant frataxin and has been found to regulate the last step of heme biosynthesis. Here, we report of the involvement of AtFH in heme catabolism by regulating the activity of heme oxygenase. AtFH forms a homodimer, and its crystal structure shows the dimeric interactions. A structural comparison with known frataxin structures suggests the iron binding sites, and the site for heme oxygenase activity is possibly located in a region containing Glu78. The results indicate a previously uncharacterized role of plant frataxin in heme catabolism.