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Structural mechanisms for the S‐nitrosylation‐derived protection of mouse galectin‐2 from oxidation‐induced inactivation revealed by NMR
Author(s) -
Sakakura Masayoshi,
Tamura Mayumi,
Fujii Norihiko,
Takeuchi Tomoharu,
Hatanaka Tomomi,
Kishimoto Seishi,
Arata Yoichiro,
Takahashi Hideo
Publication year - 2018
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14397
Subject(s) - chemistry , galectin , microbiology and biotechnology , s nitrosylation , galectin 3 , biochemistry , biophysics , biology , cysteine , immunology , enzyme
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 2 O 2 ) 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 2 O 2 -induced inactivation. One of the two cysteine residues, C57, has been identified as being responsible for controlling H 2 O 2 -induced inactivation; however, the underlying molecular mechanism has not been elucidated. We performed structural analyses of mGal-2 using nuclear magnetic resonance (NMR) and found that residues near C57 experienced significant chemical shift changes following S-nitrosylation, and that S-nitrosylation slowed the H 2 O 2 -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 2 O 2 -induced aggregation without changing its sugar-binding profile: (a) stabilization of the hydrophobic pocket around C57 that prevents oxidation-induced destabilization of the pocket, and (b) prevention of oxidation of C57 during the transiently unfolded state of the protein, in which the residue is exposed to H 2 O 2 .