title: Peroxidase activation of cytoglobin by anionic phospholipids: Mechanisms and consequences.
abstract: Cytoglobin (Cygb) is a hexa-coordinated hemoprotein with yet to be defined physiological functions. The iron coordination and spin state of the Cygb heme group are sensitive to oxidation of two cysteine residues (Cys38/Cys83) and/or the binding of free fatty acids. However, the roles of redox vs lipid regulators of Cygb's structural rearrangements in the context of the protein peroxidase competence are not known. Searching for physiologically relevant lipid regulators of Cygb, here we report that anionic phospholipids, particularly phosphatidylinositolphosphates, affect structural organization of the protein and modulate its iron state and peroxidase activity both conjointly and/or independently of cysteine oxidation. Thus, different anionic lipids can operate in cysteine-dependent and cysteine-independent ways as inducers of the peroxidase activity. We establish that Cygb's peroxidase activity can be utilized for the catalysis of peroxidation of anionic phospholipids (including phosphatidylinositolphosphates) yielding mono-oxygenated molecular species. Combined with the computational simulations we propose a bipartite lipid binding model that rationalizes the modes of interactions with phospholipids, the effects on structural re-arrangements and the peroxidase activity of the hemoprotein.
authors.affiliation: Heart, Lung, Blood, and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA. Electronic address: jet68@pitt.edu.
authors.forename: Jesús
authors.initials: J
authors.lastname: Tejero
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Alexandr A
authors.initials: AA
authors.lastname: Kapralov
authors.affiliation: Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Baumgartner
authors.affiliation: Heart, Lung, Blood, and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Courtney E
authors.initials: CE
authors.lastname: Sparacino-Watkins
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Tamil S
authors.initials: TS
authors.lastname: Anthonymutu
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Irina I
authors.initials: II
authors.lastname: Vlasova
authors.affiliation: Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address: ccamacho@pitt.edu.
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Camacho
authors.affiliation: Heart, Lung, Blood, and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA; Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Gladwin
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA 15219, USA. Electronic address: bayihx@ccm.upmc.edu.
authors.forename: Hülya
authors.initials: H
authors.lastname: Bayir
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Radiation Oncology, University of Pittsburgh, Pittsburgh, PA 15219, USA. Electronic address: kagan@pitt.edu.
authors.forename: Valerian E
authors.initials: VE
authors.lastname: Kagan
mesh_terms: D000838:Anions; D002384:Catalysis; D003545:Cysteine / Q000378:metabolism; D000078842:Cytoglobin; D004789:Enzyme Activation; D005914:Globins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007501:Iron / Q000378:metabolism; D015227:Lipid Peroxidation; D008954:Models, Biological; D056004:Molecular Dynamics Simulation; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000838:Anions; C000627265:CYGB protein, human; D000078842:Cytoglobin; D010743:Phospholipids; D011994:Recombinant Proteins; D005914:Globins; D007501:Iron; D010544:Peroxidases; D003545:Cysteine
keywords: Cytoglobin; Lipid binding; Peroxidase activity; Phosphatidylinositolphosphates