1CGO

CYTOCHROME C'

Summary for 1CGO

• Entry DOI: 10.2210/pdb1cgo/pdb
• Descriptor: CYTOCHROME C, HEME C (3 entities in total)
• Functional Keywords: electron transport (cytochrome)
• Biological source: Alcaligenes sp.
• Total number of polymer chains: 1
• Total formula weight: 14263.97

Authors

Dobbs, A.J.,Faber, H.R.,Anderson, B.F.,Baker, E.N. (deposition date: 1995-05-01, release date: 1995-07-31, Last modification date: 2024-10-23)

Primary citation

Dobbs, A.J.,Anderson, B.F.,Faber, H.R.,Baker, E.N.
Three-dimensional structure of cytochrome c' from two Alcaligenes species and the implications for four-helix bundle structures.
Acta Crystallogr.,Sect.D, 52:356-368, 1996

PubMed Abstract: The three-dimensional structures of two cytochromes c' have been determined in order to analyse the common features of proteins of this family and their relationship with other four-helix bundle structures. The structure of cytochrome c' from Alcaligenes sp was determined by molecular replacement supplemented with the iron anomalous scattering and the use of a single isomorphous heavy-atom derivative, and was refined using synchrotron data to 1.8 A resolution. The final model, comprising 956 protein atoms (one monomer) and 89 water molecules, has a final R value of 0.188 for all data in the range 20.0-1.8 A resolution (14 673 reflections). The structure of the cytochrome c' from Alcaligenes denitrificans is isomorphous and essentially identical (r.m.s. deviation for all atoms 0.36 A). Although its amino-acid sequence has not been determined chemically, only four differences from that of Alcaligenes sp cytochrome c' were identified by the X-ray analysis. The final model for Alcaligenes denitrificans cytochrome c', comprising 953 protein atoms and 75 water molecules, gave a final R factor of 0.167 for all data in the range 20.0-2.15 A (8220 reflections). The cytochrome c' monomer forms a classic four-helix bundle, determined by the packing of hydrophobic side chains around the enclosed haem group. There are very few cross-linking hydrogen bonds between the helices, the principal side-chain hydrogen bonding involving one of the haem propionates and a conserved Arg residue. The cytochrome c' dimer is created by a crystallographic twofold axis. Monomer-monomer contacts primarily involve the two A helices, with size complementarity of side chains in a central solvent-excluded portion of the interface and hydrogen bonding at the periphery. Both species have a pyroglutamic acid N-terminal residue. The haem iron is five-coordinate, 0.32 A out of the haem plane towards the fifth ligand, His120. The unusual magnetic properties of the Fe atom may be linked to a conserved basic residue, Arg124, adjacent to His120.

PubMed: 15299707
DOI: 10.1107/S0907444995008328

Experimental method

X-RAY DIFFRACTION (1.8 Å)