The first structure of a ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) from a pulse crop is reported. Rubisco was purified from Pisum sativum (garden pea) and diffraction‐quality crystals were obtained by hanging‐drop vapour diffusion in the presence of the substrate ribulose 1,5‐bisphosphate. X‐ray diffraction data were recorded to 2.20 Å resolution from a single crystal at the Canadian Light Source. The overall quaternary structure of non‐activated P. sativum Rubisco highlights the conservation of the form I Rubisco hexadecameric complex. The electron density places the substrate in the active site at the interface of the large‐subunit dimers. Lys201 in the active site is not carbamylated as expected for this non‐activated structure. Some heterogeneity in the small‐subunit sequence is noted, as well as possible variations in the conformation and contacts of ribulose 1,5‐bisphosphate in the large‐subunit active sites. Overall, the active‐site conformation most closely correlates with the `closed' conformation observed in other substrate/inhibitor‐bound Rubisco structures.
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Document Type: Research Article
Publication date: January 1, 2013