An improved Escherichia coli screen for Rubisco identifies a protein-protein interface that can enhance CO 2 -fixation kinetics.

Autor: Wilson RH; Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia., Martin-Avila E; Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia., Conlan C; Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia., Whitney SM; Research School of Biology, Australian National University, Acton, Australian Capital Territory 2601, Australia. Electronic address: spencer.whitney@anu.edu.au.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2018 Jan 05; Vol. 293 (1), pp. 18-27. Date of Electronic Publication: 2017 Oct 06.
DOI: 10.1074/jbc.M117.810861
Abstrakt: An overarching goal of photosynthesis research is to identify how components of the process can be improved to benefit crop productivity, global food security, and renewable energy storage. Improving carbon fixation has mostly focused on enhancing the CO 2 fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This grand challenge has mostly proved ineffective because of catalytic mechanism constraints and required chaperone complementarity that hinder Rubisco biogenesis in alternative hosts. Here we refashion Escherichia coli metabolism by expressing a phosphoribulokinase-neomycin phosphotransferase fusion protein to produce a high-fidelity, high-throughput Rubisco-directed evolution (RDE2) screen that negates false-positive selection. Successive evolution rounds using the plant-like Te -Rubisco from the cyanobacterium Thermosynechococcus elongatus BP1 identified two large subunit and six small subunit mutations that improved carboxylation rate, efficiency, and specificity. Structural analysis revealed the amino acids clustered in an unexplored subunit interface of the holoenzyme. To study its effect on plant growth, the Te -Rubisco was transformed into tobacco by chloroplast transformation. As previously seen for Synechocccus PCC6301 Rubisco, the specialized folding and assembly requirements of Te -Rubisco hinder its heterologous expression in leaf chloroplasts. Our findings suggest that the ongoing efforts to improve crop photosynthesis by integrating components of a cyanobacteria CO 2 -concentrating mechanism will necessitate co-introduction of the ancillary molecular components required for Rubisco biogenesis.
(© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)
Databáze: MEDLINE
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