title: Escherichia coli FtnA acts as an iron buffer for re-assembly of iron-sulfur clusters in response to hydrogen peroxide stress.
abstract: Iron-sulfur clusters are one of the most ubiquitous redox centers in biology. Ironically, iron-sulfur clusters are highly sensitive to reactive oxygen species. Disruption of iron-sulfur clusters will not only change the activity of proteins that host iron-sulfur clusters, the iron released from the disrupted iron-sulfur clusters will further promote the production of deleterious hydroxyl free radicals via the Fenton reaction. Here, we report that ferritin A (FtnA), a major iron-storage protein in Escherichia coli, is able to scavenge the iron released from the disrupted iron-sulfur clusters and alleviates the production of hydroxyl free radicals. Furthermore, we find that the iron stored in FtnA can be retrieved by an iron chaperon IscA for the re-assembly of the iron-sulfur cluster in a proposed scaffold IscU in the presence of the thioredoxin reductase system which emulates normal intracellular redox potential. The results suggest that E. coli FtnA may act as an iron buffer to sequester the iron released from the disrupted iron-sulfur clusters under oxidative stress conditions and to facilitate the re-assembly of the disrupted iron-sulfur clusters under normal physiological conditions.
authors.affiliation: Department of Biological Sciences, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Bitoun
authors.forename: Genfu
authors.initials: G
authors.lastname: Wu
authors.forename: Huangen
authors.initials: H
authors.lastname: Ding
mesh_terms: D001059:Apoproteins / Q000378:metabolism; D002021:Buffers; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000502:physiology*; D005293:Ferritins / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000096:biosynthesis* / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D001059:Apoproteins; D002021:Buffers; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; C487901:IscA protein, E coli; C411665:IscU protein, E coli; C534454:ferritin A, E coli; D017665:Hydroxyl Radical; D005293:Ferritins; D006861:Hydrogen Peroxide; D007501:Iron