Os01g0710200

This is the Oryza sativa Polyamine oxidase 1(OsPAO1)encoding gene.

Annotated Information

Oryza sativa contains seven genes encoding polyamine oxidases, termed OsPAO1 to OsPAO7 based on their chromosomal number and gene ID number.

Function

Polyamine oxidases (PAOs) are FAD-dependent enzymes involved in polyamine (PA) catabolism. In plants, the major PAs are the diamine, putrescine (Put), triamine, spermidine (Spd), tetrraamines, spermine (Spm) and thermospermine (T-Spm). These aliphatic amines of small molecular mass are involved in various biological processes, as growth factors, they play important roles in plant development, sex differentiation, fruit ripening, senility and adversity adapting.

In plants, the concentrations of all the PAs are regulated by a dynamic balance between biosynthesis and catabolism. In the latter process, two kinds of enzymes are involved: a copper-dependent diamine oxidase and a flavine adenine dinucleotide (FAD)-dependent polyamine oxidases (PAOs). Recent studies revealed that PAOs are not only active in the terminal catabolism but also in a polyamine back-conversion pathway.

Rice plant appears to contain two types of PAO enzymes: one functioning as a back-conversion enzyme, and the other as a terminal catabolism enzyme. It has been demonstrated that OsPAO1, as well as OsPAO3, OsPAO4 and OsPAO5, can catalyze the back-conversion reactions of some PAs. At different pH, T-Spm, Spm or other PAs can be chosen as the preferred substrate of OsPAO1; both these substrates will be converted to Spd but no further to Put.

Expression

Compared with other PAOs, expression of OsPAO1 appears to be quiet low under physiological conditions, and mainly localizes to the cytoplasm of onion epidermal cells. While expression of OsPAO1 can be markedly induced by spermine (Spm) or T-Spm treatmemt in rice roots, a plausible explanation of this tetraamine-induced OsPAO1 production is that excess amount of tetraamines may be detrimental for root metabolism or growth and thus OsPAO1 is inductively produced to catabolize them immediately.

Evolution

Phylogenetic analysis of the amino acid sequences of the seven O. sativa PAOs, five Arabidopsis PAOs, and several other plant PAOs have been performed [Fig.2]. Plant PAOs were divided into four clades: clade I includes Arabidopsis AtPAO1, tobacco NtPAO, and apple MdPAO1. Clade II comprises the three rice members, OsPAO2, OsPAO6, and OsPAO7, along with maize ZmPAO, barley HvPAO1, and HvPAO2. Clade III is built by OsPAO1, Brassica juncea BjPAO, and AtPAO5. In clade IV, three rice PAOs, OsPAO3, OsPAO4, and OsPAO5 were grouped together with Arabidopsis peroxisome-localized members, AtPAO2, AtPAO3, and AtPAO4.

Labs working on this gene

Graduate School of Life Sciences, Tohoku University, Japan

Faculty of Pharmaceutical Sciences, Josai University, Japan

Biodiversity and Climate Research Center, Laboratory Centre, German

References

Liu, T., Kim, D.W., Niitsu, M., Maeda, S., Watanabe, M., Kamio, Y., Berberich, T., and Kusano, T. (2014a). Polyamine Oxidase 7 is a Terminal Catabolism-Type Enzyme in Oryza sativa and is Specifically Expressed in Anthers. Plant & cell physiology.

Liu, T.B., Kim, D.W., Niitsu, M., Berberich, T., and Kusano, T. (2014b). Oryza sativa polyamine oxidase 1 back-converts tetraamines, spermine and thermospermine, to spermidine. Plant Cell Rep 33, 143-151.

Ono, Y., Kim, D.W., Watanabe, K., Sasaki, A., Niitsu, M., Berberich, T., Kusano, T., and Takahashi, Y. (2012). Constitutively and highly expressed Oryza sativa polyamine oxidases localize in peroxisomes and catalyze polyamine back conversion. Amino Acids 42, 867-876.