title: Characterization of the spermidine synthase-related gene family in Arabidopsis thaliana.
abstract: The Arabidopsis genome contains four genes that encode proteins similar to both spermidine synthase and spermine synthase of other organisms. Our previous study revealed that one of these genes, designated ACAULIS5 (ACL5), encodes spermine synthase and that its null mutation results in a severe defect in the elongation of stem internodes. Here we report the characterization of the other three genes, designated SPDS1, SPDS2 and SPDS3. Our results showed that SPDS1 and SPDS2 possess spermidine synthase activity in yeast spermidine synthase-deficient mutants, but the enzyme activity of SPDS3 remained to be determined. RNA gel blot analysis revealed that all of these genes are expressed in all plant organs but show different responses to exogenous plant hormones, suggesting that they are involved in different aspects of growth by modulating the contents of polyamines in plant cells.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, 060-0810, Sapporo, Japan.
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Hanzawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Imai
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Michael
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Komeda
authors.forename: Taku
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D005091:Exons; D018506:Gene Expression Regulation, Plant; D007438:Introns; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D011073:Polyamines / Q000378:metabolism; D011700:Putrescine / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D011436:Spermidine Synthase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D015003:Yeasts / Q000235:genetics
chemical_list: C414439:ACAULIS5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D011073:Polyamines; D011436:Spermidine Synthase; D011700:Putrescine