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Lipid binding to cytoglobin leads to a change in haem co-ordination: A role for cytoglobin in lipid signalling of oxidative stress

Reeder, BJ and Svistunenko, DA and Wilson, MT (2011) 'Lipid binding to cytoglobin leads to a change in haem co-ordination: A role for cytoglobin in lipid signalling of oxidative stress.' Biochemical Journal, 434 (3). 483 - 492. ISSN 0264-6021

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Abstract

Cytoglobin is a recently discovered hexa-co-ordinate haemoglobin that does not appear to function as a classical oxygen-binding protein. Its function is unknown and studies on the effects of changes in its expression have not decisively determined its role within the cell. In the present paper, we report that the protein is transformed from hexa-co-ordinate to penta-co-ordinate on binding a lipid molecule. This transformation occurs with the ferric oxidation state of the protein, but not the ferrous state, indicating that this process only occurs under an oxidative environment and may thus be related to redox-linked cell signalling mechanisms. Oleate binds to the protein in a 1:1 stoichiometry and with high affinity (K d =0.7 μM); however, stopped-flow kinetic measurements yield a K d value of 110 μM. The discrepancy between these K d values may be rationalized by recognizing that cytoglobin is a disulfide-linked dimer and invoking cooperativity in oleate binding. The lipid-induced transformation of cytoglobin from hexa-co-ordinate to penta-co-ordinate does not occur with similar hexa-co-ordinate haemoglobins such as neuroglobin, and therefore appears to be a unique property of cytoglobin among the haemoglobin superfamily. The lipid-derived transformationmay explain why cytoglobin has enhanced peroxidatic activity, converting lipids into various oxidized products, a property virtually absent from neuroglobin and much decreased in myoglobin. We propose that the binding of ferric cytoglobin to lipids and their subsequent transformation may be integral to the physiological function of cytoglobin, generating cell signalling lipid molecules under an oxidative environment. © The Authors Journal compilation © 2011 Biochemical Society.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Admin
Date Deposited: 04 Aug 2011 15:07
Last Modified: 19 Aug 2019 18:15
URI: http://repository.essex.ac.uk/id/eprint/384

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