44ND

Crystal structure of an oxidized form of mouse MsrA

Summary for 44ND

• Entry DOI: 10.2210/pdb44nd/pdb
• Descriptor: Mitochondrial peptide methionine sulfoxide reductase (2 entities in total)
• Functional Keywords: oxidized form, oxidoreductase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 1
• Total formula weight: 26181.56

Authors

Shin, B.M.,Kim Hawkes, H.J.,Park, S.H.,Ki, H.S.,Kim, S.H.,Shah, F.,Di Trapani, G.,Tonissen, K.F.,Hwang, K.Y. (deposition date: 2026-08-05, release date: 2026-10-28)

Primary citation

Shin, B.,Hawkes, H.K.,Park, S.,Ki, H.,Kim, S.,Shah, F.,Di Trapani, G.,Tonissen, K.F.,Hwang, K.Y.
Structural basis for cysteine-linked redox-state plasticity in mammalian methionine sulfoxide reductase A.
Redox Biol, 97:104436-104436, 2026

PubMed Abstract: Methionine sulfoxide reductase A (MsrA) protects proteins from oxidative damage through cysteine-based redox cycling, but how mammalian MsrA is structurally regulated during oxidation and reductive recycling has remained unclear. We report three crystal structures of mouse MsrA (mMsrA) that capture distinct redox states - reduced (3.0 Å), BME-trapped intermediate-like (BTIL; 1.6 Å), and oxidized (1.9 Å) - and reveal an unrecognized layer of regulation centered on Cys107. The BTIL structure visualizes catalytic Cys72 as a mixed disulfide with β-mercaptoethanol (BME) alongside a sulfenic acid at Cys107, a configuration not previously observed. The oxidized structure resolves the canonical Cys72-Cys218 disulfide together with an unexpected Cys107-Cys227 pairing that locks a C-terminal loop into a cap over the active site. LC-MS/MS mapping, MD simulations, activity assays, and thioredoxin (Trx)-trapping experiments converge on a model in which Cys72 drives catalysis, while Cys107-mediated disulfide rearrangement and Cys227-directed Trx entry gate substrate access and enzymatic regeneration - defining a noncanonical oxidized state that expands the mechanistic repertoire of mammalian MsrA under oxidative stress.

PubMed: 42860110
DOI: 10.1016/j.redox.2026.104436

Experimental method

X-RAY DIFFRACTION (1.89 Å)