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A Putative Peroxisomal Polyamine Oxidase, AtPAO4, is Involved in Polyamine Catabolism in Arabidopsis thaliana

Kamada-Nobusada, Tomoe, Hayashi, Makoto, Fukazawa, Mitsue, Sakakibara, Hitoshi, Nishimura, Mikio
Plant & cell physiology 2008 v.49 no.9 pp. 1272-1282
Arabidopsis thaliana, RNA interference, biosynthesis, gene expression, genes, microarray technology, mutants, peroxisomes, quantitative analysis, recombinant proteins, roots, spermidine, spermine, stress response, transfer DNA, water stress
We characterized three Arabidopsis polyamine oxidase genes, AtPAO2, AtPAO3 and AtPAO4. Transient expression of these genes as monomeric red fluorescent protein fusion proteins in Arabidopsis root cells revealed that all are peroxisomal proteins. Quantitative analysis of their transcripts in various organs suggested that AtPAO4 is the major isoform in root peroxisomes. Analysis of recombinant AtPAO4 protein indicated that it is a flavoprotein that catalyzed the oxidative conversion of spermine to spermidine. AtPAO4-deficient mutants established by using T-DNA insertion and RNA interference techniques had markedly increased spermine and decreased spermidine levels in the roots. These results suggest that AtPAO4 is a root peroxisomal polyamine oxidase that participates in polyamine catabolism. Microarray analysis showed that AtPAO4 deficiency induced alterations in the expression of genes related to the drought stress response and flavonoid biosynthesis.