Rubisco Activases: AAA+ Chaperones Adapted to Enzyme Repair
Javaid Y Bhat1, Gabriel Thieulin-Pardo1, F Ulrich Hartl1
1Department of Cellular Biochemistry, Max-Planck-Institute of BiochemistryMartinsried, Germany.
Frontiers in Molecular Biosciences
|April 27, 2017
Summary
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is essential for photosynthesis but inefficient. Rubisco activase (Rca) repairs Rubisco
Area of Science:
- Biochemistry
- Photosynthesis
- Enzymology
Background:
- Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the central enzyme in the Calvin-Benson-Bassham cycle, responsible for fixing atmospheric CO2.
- Rubisco is inherently inefficient and prone to inhibition by sugar phosphates, necessitating a complex activation and maintenance machinery.
- Rubisco activase (Rca) is an AAA+ protein crucial for Rubisco function, mediating ATP-dependent conformational changes to release inhibitors and restore activity.
Purpose of the Study:
- To review recent advancements in understanding the structure and function of Rubisco activase (Rca).
- To highlight the role of Rca in the biogenesis and metabolic maintenance of Rubisco.
- To explore the diversity and convergent evolution of Rca enzymes across photosynthetic organisms.
Main Methods:
- Review of existing literature on Rubisco and Rubisco activase.
- Analysis of structural and mechanistic studies of AAA+ proteins, specifically Rca.
- Comparative analysis of Rca sequences and mechanisms across different photosynthetic organisms.
Main Results:
- Rubisco activase (Rca) utilizes ATP hydrolysis to remodel Rubisco's structure, facilitating its activation and releasing inhibitory sugar phosphates.
- Rca proteins, despite sequence diversity, share a conserved AAA+ domain architecture and form hexameric ring complexes.
- The diverse mechanisms and sequences of Rca suggest convergent evolution to fulfill its essential role in Rubisco function.
Conclusions:
- Rubisco activase (Rca) is indispensable for efficient photosynthesis by ensuring the proper activation and maintenance of Rubisco.
- Understanding Rca's structure-function relationship is key to addressing Rubisco's inefficiency, a major bottleneck in crop yield improvement.
- The study of Rca provides insights into client-specific AAA+ protein function and the evolution of essential metabolic enzymes.
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