Journal
BIOCHEMICAL JOURNAL
Volume 476, Issue -, Pages 2595-2606Publisher
PORTLAND PRESS LTD
DOI: 10.1042/BCJ20190110
Keywords
-
Categories
Funding
- Biotechnology and Biological Sciences Research Council (BBSRC) [IWYP163, BB/S005072/1]
- Rothamsted Research Institute Strategic Program 20:20 Wheat(R) [BBSRC BB/J/00426X/1 20:20 Wheat(R)]
- Rothamsted Research Institute Strategic Program Designing Future Wheat [BBSRC BB/P016855/1]
- Rothamsted Research Fellowship
- Lancaster Environment Centre
- BBSRC [BBS/E/C/00005202, BBS/E/C/000I0220, BB/S005072/1] Funding Source: UKRI
Ask authors/readers for more resources
Rubisco activase (Rca) is a catalytic chaperone that remodels the active site, promotes the release of inhibitors and restores catalytic competence to Rubisco. Rca activity and its consequent effect on Rubisco activation and photosynthesis are modulated by changes to the chloroplast environment induced by fluctuations in light levels that reach the leaf, including redox status and adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio. The Triticum aestivum (wheat) genome encodes for three Rca protein isoforms: 1 beta (42.7 kDa), 2 beta (42.2 kDa) and 2 alpha (46.0 kDa). The regulatory properties of these isoforms were characterised by measuring rates of Rubisco activation and ATP hydrolysis by purified recombinant Rca proteins in the presence of physiological ADP/ATP ratios. ATP hydrolysis by all three isoforms was sensitive to inhibition by increasing amounts of ADP in the assay. In contrast, Rubisco activation activity of Rca 2 beta was insensitive to ADP inhibition, while Rca 1 beta and 2a were inhibited. Two double and one quadruple site-directed mutants were designed to elucidate if differences in the amino acid sequences between Rca 1 beta and 2 beta could explain the differences in ADP sensitivity. Changing two amino acids in Rca 2 beta to the corresponding residues in 1 beta (T358K & Q362E) resulted in significant inhibition of Rubisco activation in presence of ADP. The results show that the wheat Rca isoforms differ in their regulatory properties and that amino acid changes in the C domain influence ADP sensitivity. Advances in the understanding of Rubisco regulation will aid efforts to improve the efficiency of photosynthetic CO2 assimilation.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available