title: Molecular characterization of tobacco mitochondrial L-galactono-gamma-lactone dehydrogenase and its expression in Escherichia coli.
abstract: A cDNA clone encoding L-galactono-gamma-lactone (GAL) dehydrogenase (EC 1.3.2.3) was isolated from tobacco leaves. The cDNA clone contained an open reading frame encoding the protein of 501 amino acids with a calculated molecular mass of 56,926 Da, preceded by a putative mitochondrial targeting signal consisting of 86 amino acid residues. In fact, GAL dehydrogenase was localized in the mitochondria of tobacco cells. The deduced amino acid sequence of the cDNA showed 77 and 82% homology to cauliflower and sweet potato GAL dehydrogenases, respectively. Southern blot analysis showed that tobacco contains one copy of the gene for the enzyme. Northern blot analysis showed that GAL dehydrogenase mRNA (2.0 kb) is expressed in the leaves, stems, and roots in almost equal quantities. We introduced the cDNA clone encoding tobacco GAL dehydrogenase into a pET expression vector to overexpress this protein in Escherichia coli. The partially purified recombinant enzyme was used for comparative studies on the native enzymes from tobacco and other sources; its enzymatic properties were similar to those of other GAL dehydrogenases.
authors.affiliation: Department of Food and Nutrition, Faculty of Agriculture, Kinki University, Nakamachi, Nara, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yabuta
authors.forename: K
authors.initials: K
authors.lastname: Yoshimura
authors.forename: T
authors.initials: T
authors.lastname: Takeda
authors.forename: S
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004926:Escherichia coli; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D018515:Plant Leaves / Q000201:enzymology; D018517:Plant Roots / Q000201:enzymology; D018547:Plant Stems / Q000201:enzymology; D010947:Plants, Toxic; D010957:Plasmids; D051381:Rats; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics
chemical_list: D011994:Recombinant Proteins; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C093910:galactonolactone dehydrogenase