Escherichia coli flavohemoglobin is endowed with the notable property of binding specifically unsaturated and/or cyclopropanated fatty acids both as free acids or incorporated into a phospholipid molecule. Unsaturated or cyclopropanated fatty acid binding to the ferric heme results in a spectral change observed in the visible absorption, resonance Raman, extended x-ray absorption fine spectroscopy (EXAFS), and x-ray absorption near edge spectroscopy (XANES) spectra. Resonance Raman spectra, measured on the flavohemoglobin heme domain, demonstrate that the lipid (linoleic acid or total lipid extracts)-induced spectral signals correspond to a transition from a five-coordinated (typical of the ligand-free protein) to a hexacoordinated, high spin heme iron. EXAFS and XANES measurements have been carried out both on the lipid-free and on the lipid-bound protein to assign the nature of ligand in the sixth coordination position of the ferric heme iron. EXAFS data analysis is consistent with the presence of a couple of atoms in the sixth coordination position at 2.7 Å in the lipid-bound derivative (bonding interaction), whereas a contribution at 3.54 Å (nonbonding interaction) can be singled out in the lipid-free protein. This last contribution is assigned to the CD1 carbon atoms of the distal LeuE11, in full agreement with crystallographic data on the lipid-free protein at 1.6 Å resolution obtained in the present work. Thus, the contributions at 2.7 Å distance from the heme iron are assigned to a couple of carbon atoms of the lipid acyl chain, possibly corresponding to the unsaturated carbons of the linoleic acid.

Unusual heme iron-lipid acyl chain coordination in Escherichia coli flavohemoglobin / D'Angelo, Paola; Lucarelli, Debora; Della Longa, Stefano; Benfatto, Maurizio; Hazemann, Jean Louis; Feis, Alessandro; Smulevich, Giulietta; Ilari, Andrea; Bonamore, Alessandra; Boffi, Alberto. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - STAMPA. - 86:6(2004), pp. 3882-3892. [10.1529/biophysj.103.034876]

Unusual heme iron-lipid acyl chain coordination in Escherichia coli flavohemoglobin

D'ANGELO, Paola;ILARI, ANDREA;BONAMORE, ALESSANDRA;BOFFI, Alberto
2004

Abstract

Escherichia coli flavohemoglobin is endowed with the notable property of binding specifically unsaturated and/or cyclopropanated fatty acids both as free acids or incorporated into a phospholipid molecule. Unsaturated or cyclopropanated fatty acid binding to the ferric heme results in a spectral change observed in the visible absorption, resonance Raman, extended x-ray absorption fine spectroscopy (EXAFS), and x-ray absorption near edge spectroscopy (XANES) spectra. Resonance Raman spectra, measured on the flavohemoglobin heme domain, demonstrate that the lipid (linoleic acid or total lipid extracts)-induced spectral signals correspond to a transition from a five-coordinated (typical of the ligand-free protein) to a hexacoordinated, high spin heme iron. EXAFS and XANES measurements have been carried out both on the lipid-free and on the lipid-bound protein to assign the nature of ligand in the sixth coordination position of the ferric heme iron. EXAFS data analysis is consistent with the presence of a couple of atoms in the sixth coordination position at 2.7 Å in the lipid-bound derivative (bonding interaction), whereas a contribution at 3.54 Å (nonbonding interaction) can be singled out in the lipid-free protein. This last contribution is assigned to the CD1 carbon atoms of the distal LeuE11, in full agreement with crystallographic data on the lipid-free protein at 1.6 Å resolution obtained in the present work. Thus, the contributions at 2.7 Å distance from the heme iron are assigned to a couple of carbon atoms of the lipid acyl chain, possibly corresponding to the unsaturated carbons of the linoleic acid.
2004
01 Pubblicazione su rivista::01a Articolo in rivista
Unusual heme iron-lipid acyl chain coordination in Escherichia coli flavohemoglobin / D'Angelo, Paola; Lucarelli, Debora; Della Longa, Stefano; Benfatto, Maurizio; Hazemann, Jean Louis; Feis, Alessandro; Smulevich, Giulietta; Ilari, Andrea; Bonamore, Alessandra; Boffi, Alberto. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - STAMPA. - 86:6(2004), pp. 3882-3892. [10.1529/biophysj.103.034876]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/232262
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