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Structure and mechanism of peptide methionine sulfoxide reductase, an "anti-oxidation" enzyme

W T Lowther1, N Brot, H Weissbach

  • 1Institute of Molecular Biology, Howard Hughes Medical Institute and Department of Physics, University of Oregon, Eugene, Oregon 97403, USA.

Biochemistry
|November 7, 2000
PubMed

Insights

Peptide methionine sulfoxide reductase (MsrA) repairs oxidative damage to proteins, protecting cells from death. Structural studies reveal its unique catalytic mechanism involving cysteine residues and conformational changes.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biology

Background:

  • Oxidative stress causes damage to proteins, including methionine oxidation.
  • Peptide methionine sulfoxide reductase (MsrA) is a key enzyme that repairs methionine oxidation.
  • Cellular protection against oxidative damage is crucial for survival.

Purpose of the Study:

  • To elucidate the structural basis of bovine MsrA function.
  • To understand the catalytic mechanism of MsrA in repairing protein oxidation.
  • To investigate the role of cysteine residues and conformational changes in MsrA activity.

Main Methods:

  • X-ray crystallography was used to determine the structure of bovine MsrA.
  • Analysis of two different MsrA modifications provided insights into its conformational flexibility.
  • Biochemical assays were employed to study the catalytic mechanism.

Main Results:

  • The structures revealed three cysteine residues near the active site.
  • Conformational changes in a glycine-rich C-terminal tail facilitate the convergence of thiols for catalysis.
  • A unique thiol-disulfide exchange mechanism involving essential cysteines and conserved residues was supported.

Conclusions:

  • Bovine MsrA employs a distinct catalytic mechanism to reverse methionine oxidation.
  • Structural insights highlight the importance of conformational flexibility and specific residues in MsrA's protective function.
  • Understanding MsrA's mechanism can inform strategies against oxidative stress-related damage.

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