6U2T
Crystal structure of the T-state of maize C4-phosphoenolpyruvate carboxylase in complex with malate
Summary for 6U2T
| Entry DOI | 10.2210/pdb6u2t/pdb |
| Descriptor | Phosphoenolpyruvate carboxylase, D-MALATE, SULFATE ION, ... (5 entities in total) |
| Functional Keywords | c4 metabolism, allosteric regulation, r and t states, plant protein, lyase |
| Biological source | Zea mays (Maize) |
| Total number of polymer chains | 4 |
| Total formula weight | 439621.20 |
| Authors | Carrizosa-Carbajal, E.l.,Munoz-Clares, R.A.,Gonzalez-Segura, L. (deposition date: 2019-08-20, release date: 2020-09-09, Last modification date: 2024-09-11) |
| Primary citation | Carrizosa-Carbajal, E.I.,Gonzalez-Segura, L.,Munoz-Clares, R.A. Two new T-state crystal structures of maize C 4 -phosphoenolpyruvate carboxylase reveal and suggest novel structural features of the allosteric regulation and carboxylation step. Int.J.Biol.Macromol., :135134-135134, 2024 Cited by PubMed Abstract: To get a deeper understanding of the structural bases of the allosteric transition between T and R states of plant and bacterial phosphoenolpyruvate carboxylases (PEPCs), we obtained the first T-state crystal structures of the maize photosynthetic PEPC (ZmPEPC-C) and exhaustively compared them with the previously reported R-state ZmPEPC-C and other T-state structures. We identified previously unrecognized significant conformational changes in the T state: that of the α8-α9 loop, which connects the two kinds of activator allosteric sites with the active site, the conversion of the α30 helix into a 3 helix, leading to the disorganization of the active site lid and activators allosteric sites, and the closure of the inhibitor allosteric-site lid. Additionally, we identified previously overlooked, highly conserved residues of potential interest in the allosteric transition, including two histidines whose protonation might stabilize the T state. The crystal structures reported here also suggest similar tetrameric quaternary arrangements of PEPC enzymes in the R and T states, and the location of the bicarbonate binding site, as well as the conformational changes required for the carboxylation step. Our findings and working hypothesis advance the understanding of the structural features of the allosteric PEPC enzymes and provide a foundation for future experiments. PubMed: 39208913DOI: 10.1016/j.ijbiomac.2024.135134 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.8 Å) |
Structure validation
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