title: Molecular cloning of plant spermidine synthases.
abstract: Four cDNAs for spermidine synthase (SPDS), which converts the diamine putrescine to the higher polyamine spermidine using decarboxylated S-adenosylmethionine as the co-factor, were isolated from Nicotiana sylvestris, Hyoscyamus niger, and Arabidopsis thaliana. When the N.sylvestris SPDS cDNA was expressed in a SPDS-deficient E. coli mutant, the recombinant protein showed high SPDS activity, but did not have any spermine synthase activity. The plant SPDSs have molecular masses of about 34 kDa, possess the co-factor binding motifs which have been proposed for S-adenosylmethionine, and are more homologous in amino acid sequence to tobacco putrescine N-methyltransferase (PMT) than to SPDSs from mammals and E. coli. The SPDS gene is expressed in root, stem, and leaf in N.sylvestris, whereas the PMT gene is expressed only in root. The potential evolution of plant SPDS and PMT, and their evolutionary relationships with animal SPDS are discussed.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: K
authors.initials: K
authors.lastname: Tamaki
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology; D001483:Base Sequence; D003001:Cloning, Molecular; D018744:DNA, Plant; D004926:Escherichia coli; D015870:Gene Expression; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D010947:Plants, Toxic; D017386:Sequence Homology, Amino Acid; D019657:Solanaceae / Q000201:enzymology; D011436:Spermidine Synthase / Q000235:genetics*; D014026:Nicotiana / Q000201:enzymology
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D011436:Spermidine Synthase