44NI

Crystal structure of a reduced form of mouse MsrA

This is a non-PDB format compatible entry.

Summary for 44NI

• Entry DOI: 10.2210/pdb44ni/pdb
• Descriptor: Mitochondrial peptide methionine sulfoxide reductase (1 entity in total)
• Functional Keywords: reduced form, oxidoreductase
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 1
• Total formula weight: 26023.40

Authors

Shin, B.M.,Hawkes, H.-J.K.,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 (3 Å)