Dataset for: Structural mechanisms for the S-nitrosylation-derived protection of mouse galectin-2 from oxidation-induced inactivation revealed by NMR

Galectin-2 (Gal-2) is a lectin thought to play protective roles in the gastrointestinal tract. Oxidation of mouse Gal-2 (mGal-2) by hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) results in the loss of sugar-binding activity, whereas S-nitrosylation of mGal-2, which does not change its sugar-binding profile, has been shown to protect the protein from H<sub>2</sub>O<sub>2</sub>-induced inactivation. One of the two cysteine residues, C57, has been identified as being responsible for controlling H<sub>2</sub>O<sub>2</sub>-induced inactivation; however, the underlying molecular mechanism has not been elucidated. We performed structural analyses of mGal-2 using NMR and found that residues near C57 experienced significant chemical shift changes following S-nitrosylation, and that S-nitrosylation slowed the H<sub>2</sub>O<sub>2</sub>-induced aggregation of mGal-2. We also revealed that S-nitrosylation improves the thermal stability of mGal-2, and that the solvent accessibility and/or local dynamics of residues near C57 and the local dynamics of the core-forming residues in mGal-2 are reduced by S-nitrosylation. Structural models of Gal-2 indicated that C57 is located in a hydrophobic pocket that can be plugged by S-nitrosylation, which was supported by the NMR experiments. Based on these results, we propose two structural mechanisms by which S-nitrosylation protects mGal-2 from H<sub>2</sub>O<sub>2</sub>-induced aggregation without changing its sugar-binding profile: (1) steric prevention of H<sub>2</sub>O<sub>2</sub> access to C57 by filling the hydrophobic pocket where the residue is located, and (2) dynamic prevention of H<sub>2</sub>O<sub>2</sub> access to C57 by reducing the population of the transiently unfolded state of the protein, in which the residue is exposed to H<sub>2</sub>O<sub>2</sub>.