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Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
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Highly-expressed polyamine oxidases catalyze polyamine back conversion in Brachypodium distachyon
Yoshihiro Takahashi1, Kaede Ono2, Yuuta Akamine2
1Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kyushu Sangyo University, 2-3-1 Matsukadai Higashi-ku, Fukuoka, 813-8503, Japan. ytaka@ip.kyusan-u.ac.jp.
Journal of Plant Research
|October 25, 2017
Summary
This study identifies five polyamine oxidase (PAO) enzymes in Brachypodium distachyon, revealing that BdPAO2 and BdPAO3 exhibit distinct substrate specificities, indicating significant back-conversion activity in polyamine catabolism.
Area of Science:
- Plant molecular biology
- Biochemistry
- Enzymology
Background:
- Polyamines (PAs) are crucial for plant growth and development.
- Understanding PA catabolic pathways is essential for regulating PA homeostasis.
- Flavin-containing polyamine oxidases (PAOs) are key enzymes in PA catabolism.
Purpose of the Study:
- To characterize the molecular and biochemical properties of PAO enzymes in Brachypodium distachyon.
- To elucidate the substrate specificity and catabolic pathways of major PAO isoforms.
- To investigate the role of peroxisome-targeting signals in PAO localization and function.
Main Methods:
- Bioinformatic identification of PAO isoforms in Brachypodium distachyon.
- Gene expression analysis in various above-ground tissues.
- Sequence analysis for peroxisome-targeting signals.
- Biochemical characterization of substrate specificity for selected PAO isoforms.
Main Results:
- Five PAO isoforms (BdPAO1-BdPAO5) were identified in Brachypodium distachyon.
- BdPAO2 showed the highest expression and primarily converted spermidine to putrescine.
- BdPAO3, lacking a peroxisome-targeting signal, favored spermine conversion to spermidine.
- Both characterized PAOs demonstrated significant back-conversion activity.
Conclusions:
- The major PAOs in Brachypodium distachyon possess back-conversion activity, contributing to polyamine homeostasis.
- Differential substrate specificities of BdPAO2 and BdPAO3 suggest distinct roles in polyamine catabolism.
- The presence or absence of peroxisome-targeting signals may influence PAO function and localization.
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