| Download | - View final version: Identification of interactions between abscisic acid and ribulose-1,5-bisphosphate carboxylase/oxygenase (PDF, 1.3 MiB)
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| DOI | Resolve DOI: https://doi.org/10.1371/journal.pone.0133033 |
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| Author | Search for: Galka, Marek M.1; Search for: Rajagopalan, Nandhakishore (Kishore)1; Search for: Buhrow, Leann M.1; Search for: Nelson, Kenneth (Ken)1; Search for: Switala, Jacek; Search for: Cutler, Adrian J.1; Search for: Palmer, David R. J.; Search for: Loewen, Peter C.; Search for: Abrams, Suzanne R (Sue)1; Search for: Loewen, Michele C.1 |
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| Affiliation | - National Research Council of Canada. Aquatic and Crop Resource Development
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| Format | Text, Article |
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| Subject | abscisic acid; hormone binding protein; oxygenase; ribulose 1,5 bisphosphate oxygenase; ribulosebisphosphate carboxylase; unclassified drug; vegetable protein; binding affinity; catalysis; comparative study; computer model; electron; enzyme activation; enzyme active site; enzyme activity; enzyme inhibition; enzyme structure; enzyme substrate; isothermal titration calorimetry; molecular docking; protein protein interaction; spinach; structure analysis; validation study |
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| Abstract | Abscisic acid ((+)-ABA) is a phytohormone involved in the modulation of developmental processes and stress responses in plants. A chemical proteomics approach using an ABA mimetic probe was combined with in vitro assays, isothermal titration calorimetry (ITC), xray crystallography and in silico modelling to identify putative (+)-ABA binding-proteins in crude extracts of Arabidopsis thaliana. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was identified as a putative ABA-binding protein. Radiolabelled-binding assays yielded a Kd of 47 nM for (+)-ABA binding to spinach Rubisco, which was validated by ITC, and found to be similar to reported and experimentally derived values for the native ribulose- 1,5-bisphosphate (RuBP) substrate. Functionally, (+)-ABA caused only weak inhibition of Rubisco catalytic activity (Ki of 2.1 mM), but more potent inhibition of Rubisco activation (Ki of ~ 130 μM). Comparative structural analysis of Rubisco in the presence of (+)-ABA with RuBP in the active site revealed only a putative low occupancy (+)-ABA binding site on the surface of the large subunit at a location distal from the active site. However, subtle distortions in electron density in the binding pocket and in silico docking support the possibility of a higher affinity (+)-ABA binding site in the RuBP binding pocket. Overall we conclude that (+)-ABA interacts with Rubisco. While the low occupancy (+)-ABA binding site and weak non-competitive inhibition of catalysis may not be relevant, the high affinity site may allow ABA to act as a negative effector of Rubisco activation. |
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| Publication date | 2015-07-21 |
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| Publisher | PLOS |
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| In | |
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| Language | English |
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| Peer reviewed | Yes |
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| NPARC number | 21277062 |
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| Export citation | Export as RIS |
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| Report a correction | Report a correction (opens in a new tab) |
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| Record identifier | 2fc07f90-67d4-4e1e-b2e5-1d8ffc21c44e |
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| Record created | 2015-11-10 |
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| Record modified | 2020-06-02 |
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