title: Cytoglobin ligand binding regulated by changing haem-co-ordination in response to intramolecular disulfide bond formation and lipid interaction.
abstract: Cytoglobin (Cygb) is a hexa-co-ordinate haem protein from the globin superfamily with a physiological function that is unclear. We have previously reported that the haem co-ordination is changed in the presence of lipids, potentially transforming the redox properties of the protein and hence the function of Cygb in vivo. Recent research suggests that the protein can exist in a number of states depending on the integrity and position of disulfide bonds. In the present study, we show that the monomeric protein with an internal disulfide bond between the two cysteine residues Cys38 and Cys83, interacts with lipids to induce a change in haem co-ordination. The dimeric protein with intermolecular disulfide bonds and monomeric protein without an intramolecular disulfide bond does not exhibit these changes in haem co-ordination. Furthermore, monomeric Cygb with an intramolecular disulfide bond has significantly different properties, oxidizing lipid membranes and binding ligands more rapidly as compared with the other forms of the protein. The redox state of these cysteine residues in vivo is therefore highly significant and may be a mechanism to modulate the biochemical properties of the haem under conditions of stress.
authors.affiliation: *School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K.
authors.forename: Penny
authors.initials: P
authors.lastname: Beckerson
authors.affiliation: *School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Wilson
authors.affiliation: *School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K.
authors.forename: Dimitri A
authors.initials: DA
authors.lastname: Svistunenko
authors.affiliation: *School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, U.K.
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Reeder
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D001386:Azides / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism; D000078842:Cytoglobin; D004220:Disulfides / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005914:Globins / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000378:metabolism; D008024:Ligands; D008055:Lipids / Q000737:chemistry*; D050505:Mutant Proteins / Q000378:metabolism; D019301:Oleic Acid / Q000378:metabolism; D010084:Oxidation-Reduction; D055503:Protein Multimerization; D055550:Protein Stability; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D001386:Azides; C000627265:CYGB protein, human; D000078842:Cytoglobin; D004220:Disulfides; D008024:Ligands; D008055:Lipids; D050505:Mutant Proteins; D011994:Recombinant Proteins; D019301:Oleic Acid; D006418:Heme; D002248:Carbon Monoxide; D005914:Globins; D007501:Iron; D001205:Ascorbic Acid