Volume 80, Issue 3 pp. 703-712
Research Article

Ligand-induced formation of transient dimers of mammalian 12/15-lipoxygenase: A key to allosteric behavior of this class of enzymes?

Igor Ivanov

Corresponding Author

Igor Ivanov

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, D-13346 Berlin, Germany

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Oudenarder Str. 16, D-13346 Berlin, Germany===Search for more papers by this author
Weifeng Shang

Weifeng Shang

European Molecular Biology Laboratory Outstation, c/o DESY, D-22603 Hamburg, Germany

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Lea Toledo

Lea Toledo

Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

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Laura Masgrau

Laura Masgrau

Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

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Dmitri I. Svergun

Dmitri I. Svergun

European Molecular Biology Laboratory Outstation, c/o DESY, D-22603 Hamburg, Germany

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Sabine Stehling

Sabine Stehling

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, D-13346 Berlin, Germany

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Hansel Gómez

Hansel Gómez

Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

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Almerinda Di Venere

Almerinda Di Venere

IRCCS Neuromed, Pozzilli, and Department of Experimental Medicine and Biochemical Sciences, University of Tor Vergata, 00133 Rome, Italy

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Giampiero Mei

Giampiero Mei

IRCCS Neuromed, Pozzilli, and Department of Experimental Medicine and Biochemical Sciences, University of Tor Vergata, 00133 Rome, Italy

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José M. Lluch

José M. Lluch

Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

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Ewa Skrzypczak-Jankun

Ewa Skrzypczak-Jankun

Urology Research Center, College of Medicine, University of Toledo, Toledo, Ohio 43614

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Àngels González-Lafont

Àngels González-Lafont

Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Institut de Biotecnologia i de Biomedicina (IBB), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

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Hartmut Kühn

Corresponding Author

Hartmut Kühn

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, D-13346 Berlin, Germany

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Oudenarder Str. 16, D-13346 Berlin, Germany===Search for more papers by this author
First published: 19 October 2011
Citations: 35

Abstract

Mammalian lipoxygenases (LOXs) have been implicated in cellular defense response and are important for physiological homeostasis. Since their discovery, LOXs have been believed to function as monomeric enzymes that exhibit allosteric properties. In aqueous solutions, the rabbit 12/15-LOX is mainly present as hydrated monomer but changes in the local physiochemical environment suggested a monomer–dimer equilibrium. Because the allosteric character of the enzyme can hardly be explained using a single ligand binding-site model, we proposed that the binding of allosteric effectors may shift the monomer–dimer equilibrium toward dimer formation. To test this hypothesis, we explored the impact of an allosteric effector [13(S)-hydroxyoctadeca-9(Z),11(E)-dienoic acid] on the structural properties of rabbit 12/15-LOX by small-angle X-ray scattering. Our data indicate that the enzyme undergoes ligand-induced dimerization in aqueous solution, and molecular dynamics simulations suggested that LOX dimers may be stable in the presence of substrate fatty acids. These data provide direct structural evidence for the existence of LOX dimers, where two noncovalently linked enzyme molecules might work in unison and, therefore, such mode of association might be related to the allosteric character of 12/15-LOX. Introduction of negatively charged residues (W181E + H585E and L183E + L192E) at the intermonomer interface disturbs the hydrophobic dimer interaction of the wild-type LOX, and this structural alteration may lead to functional distortion of mutant enzymes. Proteins 2011. © 2012 Wiley Periodicals, Inc.

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