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Title: Biological iron-sulfur storage in a thioferrate-protein nanoparticle

Iron–sulfur clusters are ubiquitous in biology and function in electron transfer and catalysis. We assembled them from iron and cysteine sulfur on protein scaffolds. Iron is typically stored as iron oxyhydroxide, ferrihydrite, encapsulated in 12 nm shells of ferritin, which buffers cellular iron availability. We have characterized IssA, a protein that stores iron and sulfur as thioferrate, an inorganic anionic polymer previously unknown in biology. IssA forms nanoparticles reaching 300 nm in diameter and is the largest natural metalloprotein complex known. It is a member of a widely distributed protein family that includes nitrogenase maturation factors, NifB and NifX. IssA nanoparticles are visible by electron microscopy as electron-dense bodies in the cytoplasm. Purified nanoparticles appear to be generated from 20 nm units containing B 6,400 Fe atoms and B 170 IssA monomers. In support of roles in both iron–sulfur storage and cluster biosynthesis, IssA reconstitutes the [4Fe-4S] cluster in ferredoxin in vitro.
 [1] ;  [2] ; ORCiD logo [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5] ;  [5] ;  [4] ;  [3] ;  [2]
  1. Univ. of Georgia, Athens, GA (United States). Dept. of Chemistry, Dept. of Biochemistry and Molecular Biology
  2. Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology
  3. Univ. of Saskatchewan, Saskatoon, SK (Canada). Dept. of Geological Sciences and Chemistry
  4. Univ. of Georgia, Athens, GA (United States). Dept. of Chemistry
  5. Center for Epigenetics, Grand Rapids, MI (United States). Van Andel Research Inst.
Publication Date:
Grant/Contract Number:
FG05-95ER20175; GM62524
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Univ. of Georgia, Athens, GA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Institutes of Health (NIH)
Country of Publication:
United States
OSTI Identifier: