title: Physiological and biochemical characterization of three nucleoside diphosphate kinase isozymes from rice (Oryza sativa L.).
abstract: Nucleoside diphosphate kinase (NDPK) is a ubiquitous enzyme that catalyzes the transfer of the γ-phosphoryl group from a nucleoside triphosphate to a nucleoside diphosphate. In this study, we examined the subcellular localization, tissue-specific gene expression, and enzymatic characteristics of three rice NDPK isozymes (OsNDPK1-OsNDPK3). Sequence comparison of the three OsNDPKs suggested differential subcellular localization. Transient expression of green fluorescence protein-fused proteins in onion cells indicated that OsNDPK2 and OsNDPK3 are localized to plastid and mitochondria respectively, while OsNDPK1 is localized to the cytosol. Expression analysis indicated that all the OsNDPKs are expressed in the leaf, leaf sheath, and immature seeds, except for OsNDPK1, in the leaf sheath. Recombinant OsNDPK2 and OsNDPK3 showed lower optimum pH and higher stability under acidic pH than OsNDPK1. In ATP formation, all the OsNDPKs displayed lower K(m) values for the second substrate, ADP, than for the first substrate, NTP, and showed lowest and highest K(m) values for GTP and CTP respectively.
authors: Laboratory of Biochemistry, Research Faculty of Agriculture, Hokkaido University.
authors: Akihiko
authors: A
authors: Kihara
authors: Wataru
authors: W
authors: Saburi
authors: Shinji
authors: S
authors: Wakuta
authors: Myung-Hee
authors: MH
authors: Kim
authors: Shigeki
authors: S
authors: Hamada
authors: Hiroyuki
authors: H
authors: Ito
authors: Ryozo
authors: R
authors: Imai
authors: Hirokazu
authors: H
authors: Matsui
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D004795:Enzyme Stability; D004926:Escherichia coli; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology; D009701:Nucleoside-Diphosphate Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019697:Onions / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology; D010957:Plasmids; D018087:Plastids / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology; D013379:Substrate Specificity; D014169:Transformation, Bacterial
chemical_list: D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000244:Adenosine Diphosphate; D009701:Nucleoside-Diphosphate Kinase