title: Methionine sulfoxide reductase contributes to meeting dietary methionine requirements.
abstract: Methionine sulfoxide reductases are present in all aerobic organisms. They contribute to antioxidant defenses by reducing methionine sulfoxide in proteins back to methionine. However, the actual in vivo roles of these reductases are not well defined. Since methionine is an essential amino acid in mammals, we hypothesized that methionine sulfoxide reductases may provide a portion of the dietary methionine requirement by recycling methionine sulfoxide. We used a classical bioassay, the growth of weanling mice fed diets varying in methionine, and applied it to mice genetically engineered to alter the levels of methionine sulfoxide reductase A or B1. Mice of all genotypes were growth retarded when raised on chow containing 0.10% methionine instead of the standard 0.45% methionine. Retardation was significantly greater in knockout mice lacking both reductases. We conclude that the methionine sulfoxide reductases can provide methionine for growth in mice with limited intake of methionine, such as may occur in the wild.
authors.affiliation: Laboratory of Biochemistry, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA.
authors.forename: Hang
authors.initials: H
authors.lastname: Zhao
authors.forename: Geumsoo
authors.initials: G
authors.lastname: Kim
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Levine
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D004032:Diet; D050938:Glycine N-Methyltransferase / Q000378:metabolism; D008715:Methionine / Q000008:administration & dosage* / Q000097:blood; D051150:Methionine Sulfoxide Reductases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D017931:DNA Primers; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D008715:Methionine; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; D050938:Glycine N-Methyltransferase; C494511:Gnmt protein, mouse