title: Structure of Nm23-H1 under oxidative conditions.
abstract: Nm23-H1/NDPK-A, a tumour metastasis suppressor, is a multifunctional housekeeping enzyme with nucleoside diphosphate kinase activity. Hexameric Nm23-H1 is required for suppression of tumour metastasis and it is dissociated into dimers under oxidative conditions. Here, the crystal structure of oxidized Nm23-H1 is presented. It reveals the formation of an intramolecular disulfide bond between Cys4 and Cys145 that triggers a large conformational change that destabilizes the hexameric state. The dependence of the dissociation dynamics on the H2O2 concentration was determined using hydrogen/deuterium-exchange experiments. The quaternary conformational change provides a suitable environment for the oxidation of Cys109 to sulfonic acid, as demonstrated by peptide sequencing using nanoUPLC-ESI-q-TOF tandem MS. From these and other data, it is proposed that the molecular and cellular functions of Nm23-H1 are regulated by a series of oxidative modifications coupled to its oligomeric states and that the modified cysteines are resolvable by NADPH-dependent reduction systems. These findings broaden the understanding of the complicated enzyme-regulatory mechanisms that operate under oxidative conditions.
authors.affiliation: The Center for Cell Signaling and Drug Discovery Research, College of Pharmacy, Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul, Republic of Korea.
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Jaeho
authors.initials: J
authors.lastname: Jeong
authors.forename: Jihye
authors.initials: J
authors.lastname: Jeong
authors.forename: Dong-Hae
authors.initials: DH
authors.lastname: Shin
authors.forename: Kong-Joo
authors.initials: KJ
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry / Q000235:genetics; D004220:Disulfides / Q000737:chemistry; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D054778:NM23 Nucleoside Diphosphate Kinases / Q000737:chemistry* / Q000235:genetics; D018384:Oxidative Stress / Q000235:genetics*; D011487:Protein Conformation; D055550:Protein Stability
chemical_list: D003432:Cross-Linking Reagents; D004220:Disulfides; D054778:NM23 Nucleoside Diphosphate Kinases; C517938:NME1 protein, human; D003545:Cysteine
keywords: conformational change; disulfides; hydrogen/deuterium exchange; mass spectrometry; oxidative modification; sulfonic acid