title: A plant spermine oxidase/dehydrogenase regulated by the proteasome and polyamines.
abstract: Polyamine oxidases (PAOs) are flavin-dependent enzymes involved in polyamine catabolism. In Arabidopsis five PAO genes (AtPAO1-AtPAO5) have been identified which present some common characteristics, but also important differences in primary structure, substrate specificity, subcellular localization, and tissue-specific expression pattern, differences which may suggest distinct physiological roles. In the present work, AtPAO5, the only so far uncharacterized AtPAO which is specifically expressed in the vascular system, was partially purified from 35S::AtPAO5-6His Arabidopsis transgenic plants and biochemically characterized. Data presented here allow AtPAO5 to be classified as a spermine dehydrogenase. It is also shown that AtPAO5 oxidizes the polyamines spermine, thermospermine, and N(1)-acetylspermine, the latter being the best in vitro substrate of the recombinant enzyme. AtPAO5 also oxidizes these polyamines in vivo, as was evidenced by analysis of polyamine levels in the 35S::AtPAO5-6His Arabidopsis transgenic plants, as well as in a loss-of-function atpao5 mutant. Furthermore, subcellular localization studies indicate that AtPAO5 is a cytosolic protein undergoing proteasomal control. Positive regulation of AtPAO5 expression by polyamines at the transcriptional and post-transcriptional level is also shown. These data provide new insights into the catalytic properties of the PAO gene family and the complex regulatory network controlling polyamine metabolism.
authors.affiliation: Department of Science, University 'ROMA TRE', Rome, Italy.
authors.forename: Abdellah
authors.initials: A
authors.lastname: Ahou
authors.forename: Damiano
authors.initials: D
authors.lastname: Martignago
authors.forename: Osama
authors.initials: O
authors.lastname: Alabdallah
authors.forename: Raffaela
authors.initials: R
authors.lastname: Tavazza
authors.forename: Pasquale
authors.initials: P
authors.lastname: Stano
authors.forename: Alberto
authors.initials: A
authors.lastname: Macone
authors.forename: Micaela
authors.initials: M
authors.lastname: Pivato
authors.forename: Antonio
authors.initials: A
authors.lastname: Masi
authors.forename: Jose L
authors.initials: JL
authors.lastname: Rambla
authors.forename: Francisco
authors.initials: F
authors.lastname: Vera-Sirera
authors.forename: Riccardo
authors.initials: R
authors.lastname: Angelini
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Federico
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Tavladoraki
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D011073:Polyamines / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D015854:Up-Regulation; D000097667:Polyamine Oxidase
chemical_list: D000587:Oxidoreductases Acting on CH-NH Group Donors; D011073:Polyamines; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins; D000097667:Polyamine Oxidase
keywords: Acetylated polyamines; dehydrogenase; polyamine oxidase; polyamines; spermidine; spermine; thermospermine.