Insights into eukaryotic Rubisco assembly — Crystal structures of RbcX chaperones from Arabidopsis thaliana |
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Authors: | Piotr Kolesinski Przemyslaw Golik Przemyslaw Grudnik Janusz Piechota Michał Markiewicz Miroslaw Tarnawski Grzegorz Dubin Andrzej Szczepaniak |
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Affiliation: | 1. Laboratory of Biophysics, Faculty of Biotechnology, University of Wroclaw, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland;2. Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland;3. Department of Computational Biophysics and Bioinformatics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland;4. Malopolska Centre of Biotechnology, Gronostajowa 7a, 30-387, Krakow, Poland |
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Abstract: | BackgroundChloroplasts were formed by uptake of cyanobacteria into eukaryotic cells ca. 1.6 billion years ago. During evolution most of the cyanobacterial genes were transferred from the chloroplast to the nuclear genome. The rbcX gene, encoding an assembly chaperone required for Rubisco biosynthesis in cyanobacteria, was duplicated. Here we demonstrate that homologous eukaryotic chaperones (AtRbcX1 and AtRbcX2) demonstrate different affinities for the C-terminus of Rubisco large subunit and determine their crystal structures.MethodsThree-dimensional structures of AtRbcX1 and AtRbcX2 were resolved by the molecular replacement method. Equilibrium binding constants of the C-terminal RbcL peptide by AtRbcX proteins were determined by spectrofluorimetric titration. The binding mode of RbcX–RbcL was predicted using molecular dynamic simulation.ResultsWe provide crystal structures of both chaperones from Arabidopsis thaliana providing the first structural insight into Rubisco assembly chaperones form higher plants. Despite the low sequence homology of eukaryotic and cyanobacterial Rubisco chaperones the eukaryotic counterparts exhibit surprisingly high similarity of the overall fold to previously determined prokaryotic structures. Modeling studies demonstrate that the overall mode of the binding of RbcL peptide is conserved among these proteins. As such, the evolution of RbcX chaperones is another example of maintaining conserved structural features despite significant drift in the primary amino acid sequence.General significanceThe presented results are the approach to elucidate the role of RbcX proteins in Rubisco assembly in higher plants. |
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Keywords: | RbcX Rubisco assembly Arabidopsis thaliana |
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