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Ornithine: the overlooked molecule in the regulation of polyamine metabolismAuthor(s): Rajtilak Majumdar; Lin Shao; Rakesh Minocha; Stephanie Long; Subhash C. Minocha
Source: Plant & Cell Physiology. 54(6): 990-1004.[with supplementary document].
Publication Series: Scientific Journal (JRNL)
Station: Northern Research Station
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DescriptionWe overexpressed a mouse ornithine decarboxylase gene under the control of a constitutive and an estradiol-inducible promoter in Arabidopsis thaliana to increase our understanding of the regulation of polyamine metabolism. Of particular interest was the role of the substrate ornithine not only in the regulation of polyamine biosynthesis, but also in the accumulation of related amino acids in response to short-term induction of this enzyme. We hypothesized that the inducible expression of the transgene would mimic the natural responses of plants to changing conditions, e.g. under stress conditions and during rapid growth. Our results reveal that ornithine, even though present in relatively small quantities (compared with other amino acids of the glutamate-arginine-proline pathway), may not only be the key regulator of polyamine biosynthesis in Arabidopsis, but it may also regulate the entire subset of pathways for glutamate to arginine and to proline. Indirectly, it could also regulate putrescine catabolism, therefore contributing to the λ-aminobutyric acid content of the cells. Furthermore, the induction of mouse ornithine decarboxylase resulted in up- and down-regulation of several amino acids in the transgenic plants. It was learned that the turnover of putrescine in both the wild type and the transgenic plants occurs rapidly, with a half-life of 6-8 h.
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CitationMajumdar, Rajtilak; Shao, Lin; Minocha, Rakesh; Long, Stephanie; Minocha, Subhash C. 2013. Ornithine: the overlooked molecule in the regulation of polyamine metabolism. Plant & Cell Physiology. 54(6): 990-1004.[with supplementary document].
KeywordsArabidopsis thaliana, Polyamines, Metabolism, Ornithine, Putrescine
- Ornithine: at the crossroads of multiple paths to amino acids and polyamines
- Transgenic manipulation of a single polyamine in poplar cells affects the accumulation of all amino acids
- Living with high putrescine: expression of ornithine and arginine biosynthetic pathway genes in high and low putrescine producing poplar cells
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