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Characterization of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase activase isoforms reveals hexameric assemblies with increased thermal stability
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Keown, Jeremy R. and Pearce, Frederick Grant (2014) Characterization of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase activase isoforms reveals hexameric assemblies with increased thermal stability. Biochemical Journal, 464 (3). pp. 413-423. doi:10.1042/BJ20140676 ISSN 0264-6021.
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Official URL: http://doi.org/10.1042/BJ20140676
Abstract
Most plants contain two isoforms of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (Rca), a chloroplast protein that maintains the activity of Rubisco during photosynthesis. The longer (α-) Rca isoform has previously been shown to regulate the activity of Rubisco in response to both the ADP:ATP ratio and redox potential via thioredoxin-f. We have characterized the arrangement of the different spinach (Spinacia oleracea) isoforms in solution, and show how the presence of nucleotides changes the oligomeric state. Although the shorter (β-) isoform from both tobacco (Nicotiana tabacum) and spinach tend to form a range of oligomers in solution, the size of which are relatively unaffected by the addition of nucleotide, the spinach α-isoform assembles as a hexamer in the presence of adenosine 5′-[γ-thio]triphosphate (ATPγS). These hexamers have significantly higher heat stability, and may play a role in optimizing photosynthesis at higher temperatures. Hexamers were also observed for mixtures of the two isoforms, suggesting that the α-isoform can act as a structural scaffold for hexamer formation by the β-isoform. Additionally, it is shown that a variant of the tobacco β-isoform acts in a similar fashion to the α-isoform of spinach, forming thermally stable hexamers in the presence of ATPγS. Both isoforms had similar rates of ATP hydrolysis, suggesting that a propensity for hexamer formation may not necessarily be correlated with activity. Modelling of the hexameric structures suggests that although the N-terminus of Rca forms a highly dynamic, extended structure, the C-terminus is located adjacent to the intersubunit interface.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- ) | ||||
Journal or Publication Title: | Biochemical Journal | ||||
Publisher: | Portland Press | ||||
ISSN: | 0264-6021 | ||||
Official Date: | December 2014 | ||||
Dates: |
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Volume: | 464 | ||||
Number: | 3 | ||||
Page Range: | pp. 413-423 | ||||
DOI: | 10.1042/BJ20140676 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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