Methionine sulfoxide reduction and the aging process

Abstract

Aging has been described for multicellular and asymmetri-cally dividing organisms, but the mechanisms are poorly understood. Ox-idation of proteins is considered to be one of the major factors that leadsto aging. Oxidative damage to proteins results in the oxidation of certainamino acid residues, among which oxidation of sulfur-containing aminoacids, methionine and cysteine, is notable because of the susceptibility ofthese residues to damage, and occurrence of repair mechanisms. Methio-nine sulfoxide reductases, MsrA and MsrB, are thioredoxin-dependentoxidoreductases that reduce oxidized forms of methionine, methioninesulfoxides, in a stereospecific manner. These enzymes are present in allcell types and have shown to be regulating life spans in mammals, insects,and yeast. Here, their roles in modulating yeast life span are discussed.