TSRI's main web site PROMISE mirror at TSRI Metalloprotein DB site Created: 28 January 1997
Last modified: 5 February 1998

Ferroxidase family
Protein Binuclear iron centre Iron ligands Formal iron
oxidation states
Fe1
Fe2
Bacterioferritin (reduced)
Binuclear iron centre 1
NdeltaHis;

OepsilonGlu

NdeltaHis;

OepsilonGlu

2×FeII
2 × µ­eta1:eta1­OepsilonGlu
Bacterioferritin (oxidised)
Binuclear iron centre 2
NdeltaHis;

OepsilonGlu;

H2O

NdeltaHis;

2 × OepsilonGlu

2×FeIII
µ­eta1:eta1­OepsilonGlu;

µ­O

Human ferritin (H­chain)
Human H-ferritin
NdeltaHis;

eta1­OepsilonGlu;

H2O

2 × eta1­OepsilonGlu
2×FeII; 2×FeIII
µ­eta1:eta1­OepsilonGlu
E. coli ferritin
E. coli ferritin
NdeltaHis;

eta2­OepsilonGlu

eta1­OepsilonGlu;

eta2­OepsilonGlu

2×FeII; 2×FeIII
µ­eta1:eta1­OepsilonGlu
Rubrerythrin
rubrerythrin binuclear centre image
eta1­OepsilonGlu;

eta2­OepsilonGlu

NdeltaHis;

eta2­OepsilonGlu

2×FeII; 2×FeIII
2 × µ­eta1:eta1­OepsilonGlu;

µ­O

Nordlund and Eklund [1] recognised four classes of diiron-carboxylate proteins. Class II (simple helix­bundle proteins with overhead connection) includes the iron storage protein ferritin, the haem protein bacterioferritin (BFR) and rubrerythrin (Rr), which is a fusion protein containing an N­terminal diiron­binding domain and a C­terminal domain homologous to rubredoxin [2]. Like Class I, Class II proteins are characterised by the presence of a duplicated motif each consisting of two consecutive helices: an iron­coordinating Glu residue is located in the first helix and a Glu­X­X­His motif in the second. The second helix pair is linked to the first pair by a left­handed crossover connection.

Ferritins and BFR play a key role in iron metabolism. Steps in iron storage within ferritin molecules consist of Fe2+ oxidation (1), Fe3+ migration and the nucleation and growth of the iron core mineral [3].

The physiological role of rubrerythrin has not been identified; however, recombinant Rr oxidised by O2 shows ferroxidase activity (1) in vitro [4]. Thus, Class II proteins exhibit both structural and functional similarity, suggesting that they belong to the ferroxidase family [5].

Ferroxidases in PROMISE

PROMISE ID Description
BACFERRITIN Bacterioferritin (aka cytochrome b1 and cytochrome b557)
FERRITIN Ferritins
RUBRERYTHRIN Rubrerythrin

Ferroxidases in motif databases

PRINTS ID PRINTS AC PROSITE/BLOCKS ID PROSITE AC BLOCKS AC
BACFERRITIN PR00601 BACTERIOFERRITIN PS00549 BL00549
-
-
 FERRITIN_1 FERRITIN_2 PS00540 PS00204 BL0540

HET groups in PDB (at BSM)

HET group Description Formula HET group Description Formula
FE
Iron ion Fe2+ or Fe3+
HEM
Iron·protoporphyrin IX C34H32N4O4Fe2+/3+
PP9
Protoporphyrin IX C34H32N4O4

Ferroxidases in 3­D databases

Enzymes Iron storage proteins

Ferroxidase

  • Bacterioferritin (cytochrome b1)
  • Ferritins
  • Rubrerythrin
  • Bacterioferritin (cytochrome b1)
  • Ferritins

    • References

    1. Nordlund, P. and Eklund, H. (1995) Di­iron-carboxylate proteins. Curr. Opin. Struct. Biol. 5, 758-766.
    2. van Beeumen, J.J., van Driessche, G., Liu, M.Y. and LeGall, J. (1991) The primary structure of rubrerythrin, a protein with inorganic pyrophosphatase activity from Desulfovibrio vulgaris. Comparison with hemerythrin and rubredoxin. J. Biol. Chem. 266, 20645-20653.
    3. Harrison, P.M. and Arosio, P. (1996) The ferritins: molecular properties, iron storage function and cellular regulation. Biochim. Biophys. Acta 1275, 161-203.
    4. Bonomi, F., Kurtz, D.M., Jr. and Cui, X. (1996) Ferroxidase activity of recombinant Desulfovibrio vulgaris rubrerythrin. J. Biol. Inorg. Chem. 1, 67-72.
    5. deMaré, F., Kurtz, D.M., Jr. and Nordlund, P. (1996) The structure of Desulfovibrio vulgaris rubrerythrin reveals a unique combination of rubredoxin­like FeS4 and ferritin­like diiron domains. Nature Struct. Biol. 3, 539-546.