The Pseudoenzyme PDX1.2 Boosts Vitamin B6 Biosynthesis under Heat and Oxidative Stress in Arabidopsis

Vitamin B6 is an indispensable compound for survival, well known as a cofactor for numerous central metabolic enzymes and more recently for playing a role in several stress responses, particularly in association with oxidative stress. Regulatory aspects for the use of the vitamin in these roles are...

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Published inThe Journal of biological chemistry Vol. 289; no. 12; pp. 8203 - 8216
Main Authors Moccand, Cyril, Boycheva, Svetlana, Surriabre, Pedro, Tambasco-Studart, Marina, Raschke, Maja, Kaufmann, Markus, Fitzpatrick, Teresa B.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 21.03.2014
American Society for Biochemistry and Molecular Biology
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Summary:Vitamin B6 is an indispensable compound for survival, well known as a cofactor for numerous central metabolic enzymes and more recently for playing a role in several stress responses, particularly in association with oxidative stress. Regulatory aspects for the use of the vitamin in these roles are not known. Here we show that certain plants carry a pseudoenzyme (PDX1.2), which is involved in regulating vitamin B6 biosynthesis de novo under stress conditions. Specifically, we demonstrate that Arabidopsis PDX1.2 enhances the activity of its catalytic paralogs by forming a heterododecameric complex. PDX1.2 is strongly induced by heat as well as singlet oxygen stress, concomitant with an enhancement of vitamin B6 production. Analysis of pdx1.2 knockdown lines demonstrates that boosting vitamin B6 content is dependent on PDX1.2, revealing that this pseudoenzyme acts as a positive regulator of vitamin B6 biosynthesis during such stress conditions in plants. Background: A non-catalytic vitamin B6 biosynthesis protein (PDX1.2) exists in plants, but its role is unknown. Results: PDX1.2 interacts with its catalytic counterparts, enhancing their activity and forming a dodecameric complex induced under abiotic stress. Conclusion: PDX1.2 is a pesudoenzyme that regulates vitamin B6 biosynthesis under abiotic stress. Significance: This work presents a model for regulation of vitamin B6 biosynthesis and the existence/significance of pseudoenzymes in plants.
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Both authors contributed equally to this work.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M113.540526