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Solution structure of Methylophilus methylotrophus cytochrome c": insights into the structural basis of haem-ligand detachment

Solution structure of Methylophilus methylotrophus cytochrome c": insights into the structural basis of haem-ligand detachment
Solution structure of Methylophilus methylotrophus cytochrome c": insights into the structural basis of haem-ligand detachment
Cytochrome c" from Methylophilus methylotrophus is a monohaem protein with 124 amino acid residues. The iron has two histidine ligands in the oxidised form, one of which detaches and picks up a proton when the protein is reduced. Thus, both forms are paramagnetic. The structure of the oxidised form in solution, determined from NMR data is presented. The family of structures has an average backbone rmsd value of 0.53 Angstrom, and a heavy atom rmsd value of 0.95 Angstrom, within a target function range of 32 %. This structure is related to class I cytochromes with an additional helix at the N terminus. The haem-binding site occurs in a domain essentially lacking secondary structure motifs and the axial histidinyl residues were found in an unusual near perpendicular orientation. Moreover, a disulfide bridge is present, an uncommon structural feature among c-type cytochromes. The disulfide bridge, linking cysteine residues 96 and 104, forms a loop that confers rigidity and is essential to the detachment of the axial histidine (His95) as demonstrated by chemical disruption of the S-S bond. A route for protonation of the distal histidine involving haem propionate 17 is proposed and discussed in the light of available models for complex membrane proton pumps.
cytochrome c", ligand detachment, disulfide bridge, redox-bohr effect, proton pump, c-type cytochromes, rhodobacter-sphaeroides, chemical-shifts, paramagnetic metalloprotein, perpendicular orientation, relaxationmeasurements, protein structures, tocsy experiments, cross relaxation, proton-transfer
0022-2836
353-365
Brennan, Lorraine
efa9251d-9605-48ae-b1b0-27129a4a9270
Turner, David L.
6c4c1ccb-a6f2-47cf-944e-e69269198a29
Fareleira, Paula
cad193fd-1ab4-41aa-a4f7-87a066b0ed26
Santos, Helena
1c7cb520-ed15-41e7-b381-467ca075ed30
Brennan, Lorraine
efa9251d-9605-48ae-b1b0-27129a4a9270
Turner, David L.
6c4c1ccb-a6f2-47cf-944e-e69269198a29
Fareleira, Paula
cad193fd-1ab4-41aa-a4f7-87a066b0ed26
Santos, Helena
1c7cb520-ed15-41e7-b381-467ca075ed30

Brennan, Lorraine, Turner, David L., Fareleira, Paula and Santos, Helena (2001) Solution structure of Methylophilus methylotrophus cytochrome c": insights into the structural basis of haem-ligand detachment. Journal of Molecular Biology, 308 (2), 353-365. (doi:10.1006/jmbi.2001.4600).

Record type: Article

Abstract

Cytochrome c" from Methylophilus methylotrophus is a monohaem protein with 124 amino acid residues. The iron has two histidine ligands in the oxidised form, one of which detaches and picks up a proton when the protein is reduced. Thus, both forms are paramagnetic. The structure of the oxidised form in solution, determined from NMR data is presented. The family of structures has an average backbone rmsd value of 0.53 Angstrom, and a heavy atom rmsd value of 0.95 Angstrom, within a target function range of 32 %. This structure is related to class I cytochromes with an additional helix at the N terminus. The haem-binding site occurs in a domain essentially lacking secondary structure motifs and the axial histidinyl residues were found in an unusual near perpendicular orientation. Moreover, a disulfide bridge is present, an uncommon structural feature among c-type cytochromes. The disulfide bridge, linking cysteine residues 96 and 104, forms a loop that confers rigidity and is essential to the detachment of the axial histidine (His95) as demonstrated by chemical disruption of the S-S bond. A route for protonation of the distal histidine involving haem propionate 17 is proposed and discussed in the light of available models for complex membrane proton pumps.

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More information

Published date: 27 April 2001
Keywords: cytochrome c", ligand detachment, disulfide bridge, redox-bohr effect, proton pump, c-type cytochromes, rhodobacter-sphaeroides, chemical-shifts, paramagnetic metalloprotein, perpendicular orientation, relaxationmeasurements, protein structures, tocsy experiments, cross relaxation, proton-transfer

Identifiers

Local EPrints ID: 19428
URI: http://eprints.soton.ac.uk/id/eprint/19428
ISSN: 0022-2836
PURE UUID: 3a87425b-603e-4e38-aea2-ae445598c681

Catalogue record

Date deposited: 14 Feb 2006
Last modified: 15 Jul 2019 19:27

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