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In Vitro Characterization of Thermostable CAM Rubisco Activase Reveals a Rubisco Interacting Surface Loop
- Source :
- Plant Physiology. 174:1505-1516
- Publication Year :
- 2017
- Publisher :
- Oxford University Press (OUP), 2017.
-
Abstract
- To maintain metabolic flux through the Calvin-Benson-Bassham cycle in higher plants, dead-end inhibited complexes of Rubisco must constantly be engaged and remodeled by the molecular chaperone Rubisco activase (Rca). In C3 plants, the thermolability of Rca is responsible for the deactivation of Rubisco and reduction of photosynthesis at moderately elevated temperatures. We reasoned that crassulacean acid metabolism (CAM) plants must possess thermostable Rca to support Calvin-Benson-Bassham cycle flux during the day when stomata are closed. A comparative biochemical characterization of rice (Oryza sativa) and Agave tequilana Rca isoforms demonstrated that the CAM Rca isoforms are approximately10°C more thermostable than the C3 isoforms. Agave Rca also possessed a much higher in vitro biochemical activity, even at low assay temperatures. Mixtures of rice and agave Rca form functional hetero-oligomers in vitro, but only the rice isoforms denature at nonpermissive temperatures. The high thermostability and activity of agave Rca mapped to the N-terminal 244 residues. A Glu-217-Gln amino acid substitution was found to confer high Rca activity to rice Rca. Further mutational analysis suggested that Glu-217 restricts the flexibility of the α4-β4 surface loop that interacts with Rubisco via Lys-216. CAM plants thus promise to be a source of highly functional, thermostable Rca candidates for thermal fortification of crop photosynthesis. Careful characterization of their properties will likely reveal further protein-protein interaction motifs to enrich our mechanistic model of Rca function. MOE (Min. of Education, S’pore) Published version
- Subjects :
- Models, Molecular
0106 biological sciences
0301 basic medicine
Agave tequilana
Rubisco
Physiology
Ribulose-Bisphosphate Carboxylase
Amino Acid Motifs
Carboxylic Acids
Plant Science
Photosynthesis
01 natural sciences
03 medical and health sciences
food
Agave
Enzyme Stability
Genetics
Amino Acid Sequence
Thermostable
Plant Proteins
Thermostability
Oryza sativa
biology
fungi
RuBisCO
Temperature
food and beverages
Oryza
Articles
biology.organism_classification
food.food
030104 developmental biology
Biochemistry
biology.protein
Crassulacean acid metabolism
Protein Multimerization
Flux (metabolism)
Protein Binding
010606 plant biology & botany
Subjects
Details
- ISSN :
- 15322548 and 00320889
- Volume :
- 174
- Database :
- OpenAIRE
- Journal :
- Plant Physiology
- Accession number :
- edsair.doi.dedup.....eb722dda9b621a9bf11bf441dd590de0