Constitutively and highly expressed Oryza sativa polyamine oxidases localize in peroxisomes and catalyze polyamine back conversion
Constitutively and highly expressed Oryza sativa polyamine oxidases localize in peroxisomes and catalyze polyamine back conversion
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DOI：
10.1007/s00726-011-1002-3
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发表时间：
2012-02
期刊：
影响因子：
3.5
通讯作者：
Y. Ono;D. W. Kim;Kanako Watanabe;A. Sasaki;M. Niitsu;T. Berberich;T. Kusano;Yoshihiro Takahashi-Yoshihiro-Ta
中科院分区：
文献类型：
--
作者：
Y. Ono;D. W. Kim;Kanako Watanabe;A. Sasaki;M. Niitsu;T. Berberich;T. Kusano;Yoshihiro Takahashi-Yoshihiro-Ta
多胺氧化酶（PAO）是参与多胺（PA）催化的FAD依赖性酶。最近的研究表明，植物PAO不仅在PAs的末端催化剂中具有活性，如玉米质外体PAO所示，而且在大多数拟南芥PAO所示的多胺反向转化途径中也具有活性。我们在分子水平和生化水平上对水稻PAOs进行了表征。水稻基因组含有7种PAO异构体，命名为OsPAO 1至OsPAO 7。OsPAO 3、OsPAO 4和OsPAO 5在2周龄幼苗和成熟植株中表达量最高，而OsPAO 1、OsPAO 2、OsPAO 6和OsPAO 7的表达量很低，并具有不同的组织特异性。克隆了表达量较高的三种PAOs-OsPAO 3、OsPAO 4和OsPAO 5-，并在大肠杆菌中表达了它们的基因产物。检测了纯化的OsPAO 3至OsPAO 5蛋白的酶活性。OsPAO 3以亚精胺（Spd）为底物，其次为热精胺（T-Spm）和精胺（Spm），表现出完全的PA反转化活性。OsPAO 4和OsPAO 5对Spm和T-Spm的底物专一性相似，对Spd的底物专一性不明显。这些酶还将Spm和T-Spm转化为Spd，再次表明PA的反转化活性。最后，我们发现OsPAO 3，OsPAO 4和OsPAO 5定位于过氧化物酶体。总之，这些数据揭示了组成型和高表达的O. sativa PAO定位于过氧化物酶体中并催化PA反向转化过程。
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 back-conversion pathway as shown for most Arabidopsis PAOs. We have characterizedOryza sativaPAOs at molecular and biochemical levels. The rice genome contains 7PAOisoforms that are termedOsPAO1toOsPAO7. Of the seven PAOs,OsPAO3,OsPAO4, andOsPAO5transcripts were most abundant in 2-week-old seedlings and mature plants, whileOsPAO1,OsPAO2,OsPAO6, andOsPAO7were expressed at very low levels with different tissue specificities. The more abundantly expressed PAOs—OsPAO3,OsPAO4, andOsPAO5—were cloned, and their gene products were produced inEscherichia 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 expressedO. sativaPAOs are localized in peroxisomes and catalyze PA back-conversion processes.