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Last modified: 13 February 1998

Sulphite reductase haemoprotein structure [1]

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a = 305 K; b = 23 K; c = 23 K.

PDB scop BSMRELI
Base		 Header MMS Abstract ¹
1aop s109 1aop 1geo Sulphite reductase haemoprotein (SiRHP) (oxidised, sirohaem FeIII-PO43- complex, [Fe4S4]2+) (complex with K+); Escherichia coli (expressed in Salmonella typhimurium) MS6MR5
2gep s109 2gep 1gep Sulphite reductase haemoprotein (SiRHP) (oxidised, sirohaem FeIII-SO32- complex, [Fe4S4]2+) (complex with Na+); Escherichia coli (expressed in Salmonella typhimurium) MS6MR5
1GEP image
a
1GEP active site image
b		 1GEO active site image
c

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

  1. Ribbon representation of sulphite reductase haemoprotein (SiRHP) structure complexed with sulphite (PDB code 2GEP). Domain colour­codes: subdomain 1 (81-140) = light green; subdomain 1' (347-418) = dark green; domain 2 (155-328) = violet; domain 3 (426-570) = cyan. Note there is a gap in the PDB entry (residues 185-202).
  2. SiRHP-sulphite complex (PDB code 2GEP) active centre structure (orientation same as in a). Proximal site (below the sirohaem plane): iron-sulphur cluster is ligated by four cysteine thiolates (Cys­434, Cys­440, Cys­479 and Cys­483). The sirohaem iron and Fe4S4 cluster share a thiolate ligand from Cys­483. Thr­439 and Arg­485 form hydrogen bonds to sirohaem carboxylates. Distal anion­binding site (above the sirohaem plane): basic side chains (Arg­83, Arg­153, Lys­215 and Lys­217) coordinate the sulphite (SO32-), which is bound to the sirohaem through sulphur.
  3. SiRHP-phosphate complex (PDB code 1AOP) active centre structure. Phosphate (PO43-) is bound to the sirohaem through oxygen.
All drawings were produced by using the program MOLSCRIPT [2].

References

  1. Crane, B.R., Siegel, L.M. and Getzoff, E.D. (1995) Sulfite reductase structure at 1.6 Å: Evolution and catalysis for reduction of inorganic anions. Science 270, 59-67.
  2. Kraulis, P.J. (1991) MOLSCRIPT: a program to produce both detailed and schematic plots of protein structure. J. Appl. Crystallogr. 24, 946-950.
Bibliography on structural studies of sirohaem-Fe4S4 enzymes