9R6M

Crystal structure of C14S mutant of triosephosphate isomerase from Chamydomonas reinhardtii

Summary for 9R6M

• Entry DOI: 10.2210/pdb9r6m/pdb
• Related: 4MKN 9QM7
• Descriptor: Chloroplast triosephosphate isomerase, PHOSPHATE ION (3 entities in total)
• Functional Keywords: isomerase, tim-barrel fold, chloroplast, mutant
• Biological source: Chlamydomonas reinhardtii
• Total number of polymer chains: 2
• Total formula weight: 54434.24

Authors

Fermani, S.,Fanti, S.,Gabellini, G.,Zaffagnini, M.,Meloni, M.,Peppi, G.M.E. (deposition date: 2025-05-13, release date: 2025-10-01)

Primary citation

Meloni, M.,Mattioli, E.J.,Fanti, S.,Peppi, G.M.E.,Bin, T.,Gabellini, G.,Tedesco, D.,Henri, J.,Trost, P.,Lemaire, S.D.,Calvaresi, M.,Fermani, S.,Zaffagnini, M.
Molecular and structural basis for nitrosoglutathione-dependent redox regulation of triosephosphate isomerase from Chlamydomonas reinhardtii.
Plant Sci., 362:112768-112768, 2025

PubMed Abstract: Protein S-nitrosylation is a reversible redox-based post-translational modification that plays an important role in cell signaling by modulating protein function and stability. At the molecular level, S-nitrosylation consists of the formation of a nitrosothiol (-SNO) and is primarily induced by the trans-nitrosylating agent nitrosoglutathione (GSNO). Triosephosphate isomerase (TPI), which catalyzes the interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, has been identified as a putative target of S-nitrosylation in both plant and non-plant systems. Here we investigate the molecular basis for GSNO-dependent regulation of chloroplast TPI from the model green alga Chlamydomonas reinhardtii (CrTPI). Molecular modelling identified Cys14 and Cys219 as potential sites for interaction with GSNO, though crystallography of GSNO-treated CrTPI revealed S-nitrosylation only at Cys14. To disclose GSNO target sites, we generated and characterized Cys-to-Ser variants for Cys14 and Cys219, identifying Cys219 as a key residue mediating the GSNO-dependent modulation of CrTPI activity. Molecular dynamics simulations further revealed the stabilizing interactions of S-nitrosylated cysteines with their local environments. Overall, our results indicate that CrTPI catalysis is modulated by GSNO through a redox-based mechanism involving Cys219, which highlights a conserved regulatory strategy shared with human TPI.

PubMed: 40946919
DOI: 10.1016/j.plantsci.2025.112768

Experimental method

X-RAY DIFFRACTION (3.55 Å)