title: Binding sites for interaction of peroxiredoxin 6 with surfactant protein A.
abstract: Peroxiredoxin 6 (Prdx6) is a bifunctional enzyme with peroxidase and phospholipase A2 (PLA2) activities. This protein participates in the degradation and remodeling of internalized dipalmitoylphosphatidylcholine (DPPC), the major phospholipid component of lung surfactant. We have shown previously that the PLA2 activity of Prdx6 is inhibited by the lung surfactant-associated protein called surfactant protein A (SP-A) through direct protein-protein interaction. Docking of SPA and Prdx6 was modeled using the ZDOCK (zlab.bu.edu) program in order to predict molecular sites for binding of the two proteins. The predicted peptide sequences were evaluated for binding to the opposite protein using isothermal titration calorimetry and circular dichroism measurement followed by determination of the effect of the SP-A peptide on the PLA2 activity of Prdx6. The sequences 195EEEAKKLFPK204.in the Prdx6 helix and 83DEELQTELYEIKHQIL99 in SP-A were identified as the sites for hydrophobic interaction and H(+)-bonding between the 2 proteins. Treatment of mouse endothelial cells with the SP-A peptide inhibited their recovery from lipid peroxidation associated with oxidative stress indicating inhibition of Prdx6 activity by the peptide in the intact cell.
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Saikumari Y
authors.initials: SY
authors.lastname: Krishnaiah
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Chandra
authors.initials: C
authors.lastname: Dodia
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Elena M
authors.initials: EM
authors.lastname: Sorokina
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Haitao
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Sheldon I
authors.initials: SI
authors.lastname: Feinstein
authors.affiliation: Institute for Environmental Medicine and Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Electronic address: abf@mail.med.upenn.edu.
authors.forename: Aron B
authors.initials: AB
authors.lastname: Fisher
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D054465:Peroxiredoxin VI / Q000737:chemistry*; D054467:Phospholipases A2 / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A / Q000737:chemistry*
chemical_list: D037662:Pulmonary Surfactant-Associated Protein A; D054465:Peroxiredoxin VI; D054467:Phospholipases A2
keywords: Circular dichroism; Isothermal titration calorimetry; Lung lamellar bodies; Lung surfactant; Phospholipase A(2)