title: Structure of human promyeloperoxidase (proMPO) and the role of the propeptide in processing and maturation.
abstract: Myeloperoxidase (MPO) is synthesized by neutrophil and monocyte precursor cells and contributes to host defense by mediating microbial killing. Although several steps in MPO biosynthesis and processing have been elucidated, many questions remained, such as the structure-function relationship of monomeric unprocessed proMPOversusthe mature dimeric MPO and the functional role of the propeptide. Here we have presented the first and high resolution (at 1.25 Å) crystal structure of proMPO and its solution structure obtained by small-angle X-ray scattering. Promyeloperoxidase hosts five occupied glycosylation sites and six intrachain cystine bridges with Cys-158 of the very flexible N-terminal propeptide being covalently linked to Cys-319 and thereby hindering homodimerization. Furthermore, the structure revealed (i) the binding site of proMPO-processing proconvertase, (ii) the structural motif for subsequent cleavage to the heavy and light chains of mature MPO protomers, and (iii) three covalent bonds between heme and the protein. Studies of the mutants C158A, C319A, and C158A/C319A demonstrated significant differences from the wild-type protein, including diminished enzymatic activity and prevention of export to the Golgi due to prolonged association with the chaperone calnexin. These structural and functional findings provide novel insights into MPO biosynthesis and processing.
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
authors.forename: Irina
authors.initials: I
authors.lastname: Grishkovskaya
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Martina
authors.initials: M
authors.lastname: Paumann-Page
authors.affiliation: Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, A-1190 Vienna, Austria.
authors.forename: Rupert
authors.initials: R
authors.lastname: Tscheliessnig
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Johanna
authors.initials: J
authors.lastname: Stampler
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hofbauer
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Soudi
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Sevcnikar
authors.affiliation: Department of Material Sciences and Process Engineering, Institute of Molecular Modeling and Simulation, BOKU-University of Natural Resources and Life Sciences, A-1190 Vienna, Austria.
authors.forename: Chris
authors.initials: C
authors.lastname: Oostenbrink
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Furtmüller
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria; Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Veĉna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Kristina
authors.initials: K
authors.lastname: Djinović-Carugo
authors.affiliation: Inflammation Program and Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242. Electronic address: william-nauseef@uiowa.edu.
authors.forename: William M
authors.initials: WM
authors.lastname: Nauseef
authors.affiliation: Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria. Electronic address: christian.obinger@boku.ac.at.
authors.forename: Christian
authors.initials: C
authors.lastname: Obinger
mesh_terms: D019943:Amino Acid Substitution; D037281:Calnexin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D004789:Enzyme Activation / Q000502:physiology; D004792:Enzyme Precursors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D006056:Golgi Apparatus / Q000201:enzymology / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D020014:K562 Cells; D020125:Mutation, Missense; D009195:Peroxidase / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D000072417:Protein Domains
chemical_list: D004792:Enzyme Precursors; D037281:Calnexin; D009195:Peroxidase
keywords: biosynthesis; crystallography; heme; innate immunity; myeloperoxidase