Constitutively and highly expressed Oryza sativa polyamine oxidases localize in peroxisomes and catalyze polyamine back conversion

Yusuke Ono, Dong Wook Kim, Kanako Watanabe, Ayano Sasaki, Masaru Niitsu, Thomas Berberich, Tomonobu Kusano, Yoshihiro Takahashi

    Research output: Contribution to journalArticlepeer-review

    88 Citations (Scopus)


    Polyamine oxidases (PAOs) are FAD-dependent enzymes involved in polyamine (PA) catabolism. Recent studies have revealed that plant PAOs are not only active in the terminal catabolism of PAs as demonstrated for maize apoplastic PAO but also in a polyamine backconversion pathway as shown for most Arabidopsis PAOs. We have characterized Oryza sativa PAOs at molecular and biochemical levels. The rice genome contains 7 PAO isoforms that are termed OsPAO1 to OsPAO7. Of the seven PAOs, OsPAO3, OsPAO4, and OsPAO5 transcripts were most abundant in 2-week-old seedlings and mature plants, while OsPAO1, OsPAO2, OsPAO6, and OsPAO7 were expressed at very low levels with different tissue specificities. The more abundantly expressed PAOs - OsPAO3, OsPAO4, and OsPAO5 - were cloned, and their gene products were produced in Escherichia coli. The enzymatic activities of the purified OsPAO3 to OsPAO5 proteins were examined. OsPAO3 favored spermidine (Spd) as substrate followed by thermospermine (T-Spm) and spermine (Spm) and showed a full PA back-conversion activity. OsPAO4 substrate specificity was similar to that of OsPAO5 preferring Spm and T-Spm but not Spd. Those enzymes also converted Spm and T-Spm to Spd, again indicative of PA back-conversion activities. Lastly, we show that OsPAO3, OsPAO4, and OsPAO5 are localized in peroxisomes. Together, these data revealed that constitutively and highly expressed O. sativa PAOs are localized in peroxisomes and catalyze PA back-conversion processes.

    Original languageEnglish
    Pages (from-to)867-876
    Number of pages10
    JournalAmino Acids
    Issue number2-3
    Publication statusPublished - 2012 Feb


    • Oryza sativa
    • Peroxisome
    • Polyamine
    • Polyamine oxidase
    • Substrate specificity
    • Tissue Specificity

    ASJC Scopus subject areas

    • Biochemistry
    • Clinical Biochemistry
    • Organic Chemistry


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