title: Essential role of proximal histidine-asparagine interaction in mammalian peroxidases.
abstract: In heme enzymes belonging to the peroxidase-cyclooxygenase superfamily the proximal histidine is in close interaction with a fully conserved asparagine. The crystal structure of a mixture of glycoforms of myeloperoxidase (MPO) purified from granules of human leukocytes prompted us to revise the orientation of this asparagine and the protonation status of the proximal histidine. The data we present contrast with previous MPO structures, but are strongly supported by molecular dynamics simulations. Moreover, comprehensive analysis of published lactoperoxidase structures suggest that the described proximal heme architecture is a general structural feature of animal heme peroxidases. Its importance is underlined by the fact that the MPO variant N421D, recombinantly expressed in mammalian cell lines, exhibited modified spectral properties and diminished catalytic activity compared with wild-type recombinant MPO. It completely lost its ability to oxidize chloride to hypochlorous acid, which is a characteristic feature of MPO and essential for its role in host defense. The presented crystal structure of MPO revealed further important differences compared with the published structures including the extent of glycosylation, interaction between light and heavy polypeptides, as well as heme to protein covalent bonds. These data are discussed with respect to biosynthesis and post-translational maturation of MPO as well as to its peculiar biochemical and biophysical properties.
authors.affiliation: Institute of Research in Biomedicine (IRB-Barcelona), Parc Científic, Baldiri i Reixac 10, 08028 Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Carpena
authors.forename: Pietro
authors.initials: P
authors.lastname: Vidossich
authors.forename: Klarissa
authors.initials: K
authors.lastname: Schroettner
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Calisto
authors.forename: Srijib
authors.initials: S
authors.lastname: Banerjee
authors.forename: Johanna
authors.initials: J
authors.lastname: Stampler
authors.forename: Monika
authors.initials: M
authors.lastname: Soudi
authors.forename: Paul G
authors.initials: PG
authors.lastname: Furtmüller
authors.forename: Carme
authors.initials: C
authors.lastname: Rovira
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fita
authors.forename: Christian
authors.initials: C
authors.lastname: Obinger
mesh_terms: D001216:Asparagine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D018360:Crystallography, X-Ray; D006031:Glycosylation; D006418:Heme / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006997:Hypochlorous Acid / Q000378:metabolism; D007784:Lactoperoxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007962:Leukocytes / Q000201:enzymology*; D020125:Mutation, Missense; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology
chemical_list: D002712:Chlorides; D006418:Heme; D006639:Histidine; D001216:Asparagine; D006997:Hypochlorous Acid; D007784:Lactoperoxidase; D009195:Peroxidase