Diversity of plant methionine sulfoxide reductases B and evolution of a form specific for free methionine sulfoxide

PLoS One. 2013 Jun 12;8(6):e65637. doi: 10.1371/journal.pone.0065637. Print 2013.

Abstract

Methionine can be reversibly oxidized to methionine sulfoxide (MetO) under physiological conditions. Organisms evolved two distinct methionine sulfoxide reductase families (MSRA & MSRB) to repair oxidized methionine residues. We found that 5 MSRB genes exist in the soybean genome, including GmMSRB1 and two segmentally duplicated gene pairs (GmMSRB2 and GmMSRB5, GmMSRB3 and GmMSRB4). GmMSRB2 and GmMSRB4 proteins showed MSRB activity toward protein-based MetO with either DTT or thioredoxin (TRX) as reductants, whereas GmMSRB1 was active only with DTT. GmMSRB2 had a typical MSRB mechanism with Cys121 and Cys 68 as catalytic and resolving residues, respectively. Surprisingly, this enzyme also possessed the MSRB activity toward free Met-R-O with kinetic parameters similar to those reported for fRMSR from Escherichia coli, an enzyme specific for free Met-R-O. Overexpression of GmMSRB2 or GmMSRB4 in the yeast cytosol supported the growth of the triple MSRA/MSRB/fRMSR (Δ3MSRs) mutant on MetO and protected cells against H2O2-induced stress. Taken together, our data reveal an unexpected diversity of MSRBs in plants and indicate that, in contrast to mammals that cannot reduce free Met-R-O and microorganisms that use fRMSR for this purpose, plants evolved MSRBs for the reduction of both free and protein-based MetO.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Computational Biology
  • Escherichia coli
  • Evolution, Molecular*
  • Genes, Plant / genetics*
  • Genetic Variation*
  • Methionine / analogs & derivatives*
  • Methionine / metabolism
  • Methionine Sulfoxide Reductases / genetics*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plants / enzymology*
  • Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Soybeans / genetics
  • Soybeans / growth & development
  • Stress, Physiological / physiology
  • Synteny / genetics
  • Yeasts

Substances

  • Methionine
  • Methionine Sulfoxide Reductases
  • methionine sulfoxide reductase
  • methionine sulfoxide