Modulating protein activity and cellular function by methionine residue oxidation.

The sulfur-containing amino acid residue methionine (Met) in a peptide/protein is readily oxidized to methionine sulfoxide [Met(O)] by reactive oxygen species both in vitro and in vivo. Methionine residue oxidation by oxidants is found in an accumulating number of important proteins. Met sulfoxidation activates calcium/calmodulin-dependent protein kinase II and the large conductance calcium-activated potassium channels, delays inactivation of the Shaker potassium channel ShC/B and L-type voltage-dependent calcium channels. Sulfoxidation at critical Met residues inhibits fibrillation of atherosclerosis-related apolipoproteins and multiple neurodegenerative disease-related proteins, such as amyloid beta, α-synuclein, prion, and others. Methionine residue oxidation is also correlated with marked changes in cellular activities. Controlled key methionine residue oxidation may be used as an oxi-genetics tool to dissect specific protein function in situ.