|Gene:||ftnA||Accession Numbers: EG10921 (MetaCyc), b1905, ECK1904|
Synonyms: ftn, gen-165, rsgA
Species: Escherichia coli K-12 substr. MG1655
ftnA encodes the iron-storage protein ferritin, which is similar to human ferritin H [Izuhara91, Hudson93]. Ferritin forms a multi-subunit, hollow spherical shell of 24 individual ferritin polypeptides that can sequester more than 2000 iron atoms in the center [Hudson93]. Ferritin and bacterioferritin are distantly related [Andrews91a, Andrews92].
The crystal structure of ferritin has been determined, identifying three iron-binding sites per subunit [Hempstead94, Stillman01, Stillman03]. Two of these sites form a dinuclear iron center where oxidation of Fe(II) occurs, allowing iron to be stored as ferric phosphate [Treffry98, BouAbdallah05]. The third site appears to modulate Fe2+ binding to the dinuclear iron center [BouAbdallah05]. No protons are released upon initial binding of Fe2+. Subsequent oxidation of Fe2+ leads to production of H2O2, which is itself utilized for oxidation of Fe2+ bound at other ferroxidase centers [BouAbdallah14].
In vitro, FtnA was shown to sequester iron released from damaged [2Fe-2S] clusters of IscU. Iron sequestered by FtnA can be transferred to IscA, but not IscU [Bitoun08].
Overexpression of ftnA rescues the oxygen sensitivity of a Δfur ΔrecA mutant, presumably by preventing toxic iron accumulation [Touati95]. An ftnA mutant shows impaired growth in iron-deficient media [AbdulTehrani99].
Expression of ftnA is higher in stationary phase than log phase cells and is dependent on iron and Fur [Nandal10]. Although ftnA expression was thought to be regulated by RyhB [Masse02], microarray experiments indicated that it is not dependent on RyhB [Masse05]. It was later shown that ftnA expression is directly regulated by Fur, which reverses silencing by H-NS [Nandal10].
|Map Position: [1,986,740 -> 1,987,237]|
Molecular Weight of Polypeptide: 19.424 kD (from nucleotide sequence), 19.4 kD (experimental) [Hudson93 ]
Molecular Weight of Multimer: 500.0 kD (experimental) [Hudson93]
Unification Links: ASAP:ABE-0006342 , CGSC:32521 , DIP:DIP-36198N , EchoBASE:EB0914 , EcoGene:EG10921 , EcoliWiki:b1905 , ModBase:P0A998 , OU-Microarray:b1905 , PortEco:ftnA , PR:PRO_000022712 , Pride:P0A998 , Protein Model Portal:P0A998 , RefSeq:NP_416418 , RegulonDB:EG10921 , SMR:P0A998 , String:511145.b1905 , UniProt:P0A998
Relationship Links: InterPro:IN-FAMILY:IPR001519 , InterPro:IN-FAMILY:IPR008331 , InterPro:IN-FAMILY:IPR009040 , InterPro:IN-FAMILY:IPR009078 , InterPro:IN-FAMILY:IPR012347 , Panther:IN-FAMILY:PTHR11431 , PDB:Structure:1EUM , Pfam:IN-FAMILY:PF00210 , Prosite:IN-FAMILY:PS50905
|Biological Process:||GO:0006880 - intracellular sequestering of iron ion
GO:0006974 - cellular response to DNA damage stimulus [Khil02]
GO:0006979 - response to oxidative stress [Bitoun08]
GO:0006826 - iron ion transport [GOA01a]
GO:0006879 - cellular iron ion homeostasis [UniProtGOA11a, GOA01a]
GO:0055114 - oxidation-reduction process [UniProtGOA11a]
|Molecular Function:||GO:0004322 - ferroxidase activity
GO:0008199 - ferric iron binding [GOA01a, Hudson93]
GO:0042802 - identical protein binding [Hudson93]
GO:0016491 - oxidoreductase activity [UniProtGOA11a]
GO:0046872 - metal ion binding [UniProtGOA11a]
|Cellular Component:||GO:0005829 - cytosol
[DiazMejia09, Ishihama08, Lasserre06]
GO:0005737 - cytoplasm [UniProtGOA11, UniProtGOA11a]
|MultiFun Terms:||cell processes → adaptations → Fe aquisition|
Enzymatic reaction of: non-heme bacterial ferritin (ferritin iron-storage complex)
EC Number: 126.96.36.199
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
The reaction is physiologically favored in the direction shown.
Thermodynamic parameters of Fe2+ binding to the binding sites within FtnA have been determined [BouAbdallah05].
|Conserved-Region||1 -> 145|
10/20/97 Gene b1905 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10921; confirmed by SwissProt match.
AbdulTehrani99: Abdul-Tehrani H, Hudson AJ, Chang YS, Timms AR, Hawkins C, Williams JM, Harrison PM, Guest JR, Andrews SC (1999). "Ferritin mutants of Escherichia coli are iron deficient and growth impaired, and fur mutants are iron deficient." J Bacteriol 181(5);1415-28. PMID: 10049371
Andrews91a: Andrews SC, Smith JM, Yewdall SJ, Guest JR, Harrison PM (1991). "Bacterioferritins and ferritins are distantly related in evolution. Conservation of ferroxidase-centre residues." FEBS Lett 293(1-2);164-8. PMID: 1959654
Andrews92: Andrews SC, Arosio P, Bottke W, Briat JF, von Darl M, Harrison PM, Laulhere JP, Levi S, Lobreaux S, Yewdall SJ (1992). "Structure, function, and evolution of ferritins." J Inorg Biochem 47(3-4);161-74. PMID: 1431878
Bauminger00: Bauminger ER, Treffry A, Quail MA, Zhao Z, Nowik I, Harrison PM (2000). "Metal binding at the active centre of the ferritin of Escherichia coli (EcFtnA). A Mossbauer spectroscopic study." Inorg Chim Acta 297, 171-180.
Bauminger99: Bauminger ER, Treffry A, Quail MA, Zhao Z, Nowik I, Harrison PM (1999). "Stages in iron storage in the ferritin of Escherichia coli (EcFtnA): analysis of Mossbauer spectra reveals a new intermediate." Biochemistry 38(24);7791-802. PMID: 10387019
Bitoun08: Bitoun JP, Wu G, Ding H (2008). "Escherichia coli FtnA acts as an iron buffer for re-assembly of iron-sulfur clusters in response to hydrogen peroxide stress." Biometals 21(6);693-703. PMID: 18618270
BouAbdallah05: Bou-Abdallah F, Woodhall MR, Velazquez-Campoy A, Andrews SC, Chasteen ND (2005). "Thermodynamic analysis of ferrous ion binding to Escherichia coli ferritin EcFtnA." Biochemistry 44(42);13837-46. PMID: 16229472
BouAbdallah14: Bou-Abdallah F, Yang H, Awomolo A, Cooper B, Woodhall MR, Andrews SC, Chasteen ND (2014). "Functionality of the three-site ferroxidase center of Escherichia coli bacterial ferritin (EcFtnA)." Biochemistry 53(3);483-95. PMID: 24380371
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Hempstead94: Hempstead PD, Hudson AJ, Artymiuk PJ, Andrews SC, Banfield MJ, Guest JR, Harrison PM (1994). "Direct observation of the iron binding sites in a ferritin." FEBS Lett 350(2-3);258-62. PMID: 8070575
Hudson93: Hudson AJ, Andrews SC, Hawkins C, Williams JM, Izuhara M, Meldrum FC, Mann S, Harrison PM, Guest JR (1993). "Overproduction, purification and characterization of the Escherichia coli ferritin." Eur J Biochem 218(3);985-95. PMID: 8281950
Izuhara91: Izuhara M, Takamune K, Takata R (1991). "Cloning and sequencing of an Escherichia coli K12 gene which encodes a polypeptide having similarity to the human ferritin H subunit." Mol Gen Genet 225(3);510-3. PMID: 2017145
Lasserre06: Lasserre JP, Beyne E, Pyndiah S, Lapaillerie D, Claverol S, Bonneu M (2006). "A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis." Electrophoresis 27(16);3306-21. PMID: 16858726
Nandal10: Nandal A, Huggins CC, Woodhall MR, McHugh J, Rodriguez-Quinones F, Quail MA, Guest JR, Andrews SC (2010). "Induction of the ferritin gene (ftnA) of Escherichia coli by Fe(2+)-Fur is mediated by reversal of H-NS silencing and is RyhB independent." Mol Microbiol 75(3):637-57. PMID: 20015147
Stillman01: Stillman TJ, Hempstead PD, Artymiuk PJ, Andrews SC, Hudson AJ, Treffry A, Guest JR, Harrison PM (2001). "The high-resolution X-ray crystallographic structure of the ferritin (EcFtnA) of Escherichia coli; comparison with human H ferritin (HuHF) and the structures of the Fe(3+) and Zn(2+) derivatives." J Mol Biol 307(2);587-603. PMID: 11254384
Stillman03: Stillman TJ, Connolly PP, Latimer CL, Morland AF, Quail MA, Andrews SC, Treffry A, Guest JR, Artymiuk PJ, Harrison PM (2003). "Insights into the effects on metal binding of the systematic substitution of five key glutamate ligands in the ferritin of Escherichia coli." J Biol Chem 278(28);26275-86. PMID: 12730190
Touati95: Touati D, Jacques M, Tardat B, Bouchard L, Despied S (1995). "Lethal oxidative damage and mutagenesis are generated by iron in delta fur mutants of Escherichia coli: protective role of superoxide dismutase." J Bacteriol 177(9);2305-14. PMID: 7730258
Treffry98: Treffry A, Zhao Z, Quail MA, Guest JR, Harrison PM (1998). "How the presence of three iron binding sites affects the iron storage function of the ferritin (EcFtnA) of Escherichia coli." FEBS Lett 432(3);213-8. PMID: 9720927
Treffry98a: Treffry A, Zhao Z, Quail MA, Guest JR, Harrison PM (1998). "The use of zinc(II) to probe iron binding and oxidation by the ferritin (EcFtnA) of Escherichia coli." J. Biol. Inorg. Chem. 3, 682-688.
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