• Prosthetic group features
• Rubrerythrin in SWISS­PROT/TREMBL
• Rubrerythrin in alignment databases
• Rubrerythrin in 3­D databases
• References

Iron centre		Iron ligands		Formal iron oxidation states
I		Fe1	Fe2	2×FeII; 2×FeIII
		1­OGlu; 2­OGlu	NHis; 2­OGlu
		2 × µ­1:1­OGlu; µ­O
II		4 × SCys		FeII; FeIII

Rubrerythrin (Rr), found in anaerobic sulphate­reducing bacteria [1], is a fusion protein containing an N­terminal diiron­binding domain and a C­terminal domain homologous to rubredoxin [2]. The physiological role of Rr has not been identified. Recombinant Rr oxidised by O₂ shows ferroxidase activity (oxidation of Fe²⁺ to Fe³⁺) in vitro [3].

The 3­D structure of Desulfovibrio vulgaris rubrerythrin has been solved [4]. The structure reveals a tetramer of two­domain subunits. In each monomer, the N­terminal 146 residues form a four­­helix bundle containing the diiron­oxo site (centre I), and the C­terminal 45 residues form a rubredoxin­like FeS₄ domain (see Figure 1RYT). In centre I, the two iron atoms (Fe1 and Fe2) are approximately octahedrally coordinated, with bridging oxo ion and bidentate carboxylates from Glu­52 and Glu­128. Fe1 has a terminal bidentate carboxylate ligand from Glu­20 and a terminal monodentate carboxylate ligand from Glu­97, while Fe2 has a terminal bidentate carboxylate ligand from Glu­94 and N ligand from His­131. The diiron site in Rr is located close to the protein surface, with Glu­94, Glu­97 and the µ­oxo ligands solvent accessible through a crevice between helices A and C. The pseudotetrahedral coordination of the mononuclear iron (centre II) by the sulphurs of Cys­158, Cys­161, Cys­174 and Cys­177 and the N-H···S hydrogen bonding pattern is also similar to those in rubredoxin [4].

Rubrerythrin in SWISS­PROT/TREMBL

RUBY_CLOPE	Rubrerythrin (Rr); Clostridium perfringens
RUBY_DESVH	Rubrerythrin (Rr); Desulfovibrio vulgaris (strain Hildenborough)
RUBY_METJA	Rubrerythrin (putative); Methanococcus jannaschii
NIGY_DESVH	Nigerythrin; Desulfovibrio vulgaris (strain Hildenborough)
YCX8_CYAPA	Hypothetical 20.0 kD protein in PETA-PSAM intergenic region (ORF180); Cyanophora paradoxa cyanelle
Y737_METJA	Hypothetical protein MJ0737; Methanococcus jannaschii
O26850	Rubrerythrin (Mth756); Methanobacterium thermoautotrophicum
O26912	Rubrerythrin (Mth822); Methanobacterium thermoautotrophicum
O29426	Rubrerythrin (Rr1); Archaeoglobus fulgidus
O29427	Rubrerythrin (Rr2); Archaeoglobus fulgidus
O28633	Rubrerythrin (Rr3); Archaeoglobus fulgidus
O27972	Rubrerythrin (Rr4); Archaeoglobus fulgidus
O29905	Nigerythrin (putative); Archaeoglobus fulgidus

Rubrerythrin in alignment databases

Protein Superfamily	Protein Homology Domain	Pfam	LPFC 3­D alignment
80614; rubrerythrin	00142; rubredoxin	-	-

PDB	scop	BSM	RELI Base	Header	¹
1ryt	1ryt	1ryt	1ryt	Rubrerythrin (oxidised); Desulfovibrio vulgaris (strain Hildenborough)	MS7RL3

¹ Macromolecular Structures abstract. Full text is available to BioMedNet Members

References

1. Moura, I., Tavares, P. and Ravi, N. (1994) Characterization of three proteins containing multiple iron sites: rubrerythrin, desulfoferrodoxin, and a protein containing a six­iron cluster. Methods Enzymol. 243, 216-240.
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. Bonomi, F., Kurtz, D.M., Jr. and Cui, X. (1996) Ferroxidase activity of recombinant Desulfovibrio vulgaris rubrerythrin. J. Biol. Inorg. Chem. 1, 67-72.
4. 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.

Bibliography on structural studies of rubrerythrin