Abstract
AbstractThe Calvin-Benson-Bassham cycle (CBBC) performs carbon fixation in photosynthetic organisms. Among the eleven enzymes that participate in the pathway, sedoheptulose-1,7-bisphosphatase (SBPase) is expressed in photo-autotrophs and contributes to the regeneration of ribulose-1,5-bisphosphate, the carbon fixation co-substrate used by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). While SBPase is structurally similar to fructose-1,6-bisphosphatase (FBPase) involved in both neoglucogenesis and the CBBC, it exclusively functions in the CBBC and is indispensable for building a productive cycle. In this study we report the first structure of an SBPase from a chlorophyte, the model unicellular green microalgaChlamydomonas reinhardtii. By combining experimental and computational structural analyses, we describe the topology, conformations and quaternary structure ofChlamydomonas reinhardtiiSBPase. We identify active site residues and locate sites of redox- and phospho-post-translational modifications that contribute to enzymatic functions. Finally, we observe that CrSBPase adopts distinct oligomeric states that may dynamically contribute to the control of its activity.
Publisher
Cold Spring Harbor Laboratory
Reference49 articles.
1. The Phenix software for automated determination of macromolecular structures
2. Almagro Armenteros, J. J., M. Salvatore , O. Emanuelsson , O. Winther , G. von Heijne , A. Elofsson and H. Nielsen (2019). “Detecting sequence signals in targeting peptides using deep learning.” Life Sci Alliance 2(5).
3. “Activation of pea leaf chloroplast sedoheptulose 1,7-diphosphate phosphatase by light and dithiothreitol.”;Biochem Biophys Res Commun,1974
4. “T-to-R switch of muscle fructose-1,6-bisphosphatase involves fundamental changes of secondary and quaternary structure.”;Acta Crystallogr D Struct Biol,2016