title: The hierarchy of structural transitions induced in cytochrome c by anionic phospholipids determines its peroxidase activation and selective peroxidation during apoptosis in cells.
abstract: Activation of peroxidase catalytic function of cytochrome c (cyt c) by anionic lipids is associated with destabilization of its tertiary structure. We studied effects of several anionic phospholipids on the protein structure by monitoring (1) Trp59 fluorescence, (2) Fe-S(Met80) absorbance at 695 nm, and (3) EPR of heme nitrosylation. Peroxidase activity was probed using several substrates and protein-derived radicals. Peroxidase activation of cyt c did not require complete protein unfolding or breakage of the Fe-S(Met80) bond. The activation energy of cyt c peroxidase changed in parallel with stability energies of structural regions of the protein probed spectroscopically. Cardiolipin (CL) and phosphatidic acid (PA) were most effective in inducing cyt c peroxidase activity. Phosphatidylserine (PS) and phosphatidylinositol bisphosphate (PIP2) displayed a significant but much weaker capacity to destabilize the protein and induce peroxidase activity. Phosphatidylinositol trisphosphate (PIP3) appeared to be a stronger inducer of cyt c structural changes than PIP2, indicating a role for the negatively charged extra phosphate group. Comparison of cyt c-deficient HeLa cells and mouse embryonic cells with those expressing a full complement of cyt c demonstrated the involvement of cyt c peroxidase activity in selective catalysis of peroxidation of CL, PS, and PI, which corresponded to the potency of these lipids in inducing cyt c's structural destabilization.
authors.affiliation: Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh, PA 15260, USA.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Kapralov
authors.forename: Igor V
authors.initials: IV
authors.lastname: Kurnikov
authors.forename: Irina I
authors.initials: II
authors.lastname: Vlasova
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Belikova
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Tyurin
authors.forename: Liana V
authors.initials: LV
authors.lastname: Basova
authors.forename: Quing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Yulia Y
authors.initials: YY
authors.lastname: Tyurina
authors.forename: Jianfei
authors.initials: J
authors.lastname: Jiang
authors.forename: Hulya
authors.initials: H
authors.lastname: Bayir
authors.forename: Yuri A
authors.initials: YA
authors.lastname: Vladimirov
authors.forename: Valerian E
authors.initials: VE
authors.lastname: Kagan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002308:Cardiolipins; D045304:Cytochromes c / Q000737:chemistry / Q000187:drug effects*; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D005047:Etoposide / Q000378:metabolism; D005453:Fluorescence; D006418:Heme / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D006801:Humans; D051379:Mice; D009195:Peroxidase / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000494:pharmacology; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology*; D017434:Protein Structure, Tertiary / Q000187:drug effects; D014364:Tryptophan / Q000737:chemistry
chemical_list: C519576:1,1',2,2'-tetraoleoylcardiolipin; D002308:Cardiolipins; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010718:Phosphatidylserines; D010743:Phospholipids; C037657:dioleoylphosphatidic acid; D006418:Heme; C027417:nitrosylprotoheme; D005047:Etoposide; C042511:1,2-dioleoylphosphatidylserine; D014364:Tryptophan; D045304:Cytochromes c; D009195:Peroxidase; C017251:1,2-oleoylphosphatidylcholine