Functions and evolution of selenoprotein methionine sulfoxide reductases.
Methionine sulfoxide reductases (Msrs) are thiol-dependent enzymes which catalyze conversion of methionine sulfoxide to methionine. Three Msr families, MsrA, MsrB, and fRMsr, are known. MsrA and MsrB are responsible for the reduction of methionine-S-sulfoxide and methionine-R-sulfoxide residues in proteins, respectively, whereas fRMsr reduces free methionine-R-sulfoxide. Besides acting on proteins, MsrA can additionally reduce free methionine-S-sulfoxide. Some MsrAs and MsrBs evolved to utilize catalytic selenocysteine. This includes MsrB1, which is a major MsrB in cytosol and nucleus in mammalian cells. Specialized machinery is used for insertion of selenocysteine into MsrB1 and other selenoproteins at in-frame UGA codons. Selenocysteine offers catalytic advantage to the protein repair function of Msrs, but also makes these proteins dependent on the supply of selenium and requires adjustments in their strategies for regeneration of active enzymes. Msrs have roles in protecting cellular proteins from oxidative stress and through this function they may regulate lifespan in several model organisms.
Lee
Byung Cheon
BC
Redox Biology Center and Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0664, USA.
Dikiy
Alexander
A
Kim
Hwa-Young
HY
Gladyshev
Vadim N
VN
D000375:Aging / Q000378:metabolism / Q000502:physiology; D000818:Animals; D002384:Catalysis; D019143:Evolution, Molecular; D006801:Humans; D008322:Mammals / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051150:Methionine Sulfoxide Reductases; D008954:Models, Biological; D010088:Oxidoreductases / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D051140:Selenoproteins / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology
D051140:Selenoproteins; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase