AI Article Synopsis
- CoMsrA is a selenocysteine-containing methionine-S-sulfoxide reductase that typically functions as a monomer but can dimerize during catalysis when interacting with its substrate, methionine sulfoxide.
- The dimerization occurs through an intermolecular disulfide bond between the catalytic Cys16 residues and is dependent on the concentration of the substrate and time.
- Structural analysis shows a unique crystal structure of the dimer with a cone-shaped opening at the interface, highlighting a new mechanism of enzyme catalysis and regeneration involving glutaredoxin.
Article Abstract
Clostridium oremlandii MsrA (CoMsrA) is a natively selenocysteine-containing methionine-S-sulfoxide reductase and classified into a 1-Cys type MsrA. CoMsrA exists as a monomer in solution. Herein, we report evidence that CoMsrA can undergo homodimerization during catalysis. The monomeric CoMsrA dimerizes in the presence of its substrate methionine sulfoxide via an intermolecular disulfide bond between catalytic Cys16 residues. The dimeric CoMsrA is resolved by the reductant glutaredoxin, suggesting the relevance of dimerization in catalysis. The dimerization reaction occurs in a concentration- and time-dependent manner. In addition, the occurrence of homodimer formation in the native selenoprotein CoMsrA is confirmed. We also determine the crystal structure of the dimeric CoMsrA, having the dimer interface around the two catalytic Cys16 residues. A central cone-shaped hole is present in the surface model of dimeric structure, and the two Cys16 residues constitute the base of the hole. Collectively, our biochemical and structural analyses suggest a novel dimerization-mediated mechanism for CoMsrA catalysis that is additionally involved in CoMsrA regeneration by glutaredoxin.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4479559 | PMC |
| http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131523 | PLOS |
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Article Synopsis
- CoMsrA is a selenocysteine-containing methionine-S-sulfoxide reductase that typically functions as a monomer but can dimerize during catalysis when interacting with its substrate, methionine sulfoxide.
- The dimerization occurs through an intermolecular disulfide bond between the catalytic Cys16 residues and is dependent on the concentration of the substrate and time.
- Structural analysis shows a unique crystal structure of the dimer with a cone-shaped opening at the interface, highlighting a new mechanism of enzyme catalysis and regeneration involving glutaredoxin.
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