Tissue-specific expression and post-translational modifications of plant- and bacterial-type phosphoenolpyruvate carboxylase isozymes of the castor oil plant, Ricinus communis L
| Autor: | Allyson T. Hill, William C. Plaxton, James Bettridge, Brendan O'Leary, Craig A. Leach, Joonho Park, Srinath K. Rao, Eric T. Fedosejevs |
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| Rok vydání: | 2011 |
| Předmět: |
0106 biological sciences
food.ingredient protein:protein interactions Physiology Plant Science 01 natural sciences Endosperm 03 medical and health sciences food Monoubiquitination Phosphorylation Plant Proteins 030304 developmental biology 0303 health sciences Enzyme phosphorylation biology Ricinus food and beverages metabolic control biology.organism_classification Research Papers Phosphoenolpyruvate Carboxylase Isoenzymes Citric acid cycle monoubiquitination post-translational modification Biochemistry tissue-specific gene expression Phosphoenolpyruvate carboxykinase Phosphoenolpyruvate carboxylase Protein Processing Post-Translational Cotyledon Protein Binding 010606 plant biology & botany Homotetramer |
| Zdroj: | Journal of Experimental Botany |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/err225 |
| Popis: | This study employs transcript profiling together with immunoblotting and co-immunopurification to assess the tissue-specific expression, protein:protein interactions, and post-translational modifications (PTMs) of plant- and bacterial-type phosphoenolpyruvate carboxylase (PEPC) isozymes (PTPC and BTPC, respectively) in the castor plant, Ricinus communis. Previous studies established that the Class-1 PEPC (PTPC homotetramer) of castor oil seeds (COS) is activated by phosphorylation at Ser-11 and inhibited by monoubiquitination at Lys-628 during endosperm development and germination, respectively. Elimination of photosynthate supply to developing COS by depodding caused the PTPC of the endosperm and cotyledon to be dephosphorylated, and then subsequently monoubiquitinated in vivo. PTPC monoubiquitination rather than phosphorylation is widespread throughout the castor plant and appears to be the predominant PTM of Class-1 PEPC that occurs in planta. The distinctive developmental patterns of PTPC phosphorylation versus monoubiquitination indicates that these two PTMs are mutually exclusive. By contrast, the BTPC: (i) is abundant in the inner integument, cotyledon, and endosperm of developing COS, but occurs at low levels in roots and cotyledons of germinated COS, (ii) shows a unique developmental pattern in leaves such that it is present in leaf buds and young expanding leaves, but undetectable in fully expanded leaves, and (iii) tightly interacts with co-expressed PTPC to form the novel and allosterically-desensitized Class-2 PEPC heteromeric complex. BTPC and thus Class-2 PEPC up-regulation appears to be a distinctive feature of rapidly growing and/or biosynthetically active tissues that require a large anaplerotic flux from phosphoenolpyruvate to replenish tricarboxylic acid cycle C-skeletons being withdrawn for anabolism. |
| Databáze: | OpenAIRE |
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