Ciorba M A, Heinemann S H, Weissbach H, Brot N, Hoshi T
Department of Physiology and Biophysics, Bowen 5660, The University of Iowa, Iowa City, IA 52242, USA.
Proc Natl Acad Sci U S A. 1997 Sep 2;94(18):9932-7. doi: 10.1073/pnas.94.18.9932.
Oxidation of amino acid residues in proteins can be caused by a variety of oxidizing agents normally produced by cells. The oxidation of methionine in proteins to methionine sulfoxide is implicated in aging as well as in pathological conditions, and it is a reversible reaction mediated by a ubiquitous enzyme, peptide methionine sulfoxide reductase. The reversibility of methionine oxidation suggests that it could act as a cellular regulatory mechanism although no such in vivo activity has been demonstrated. We show here that oxidation of a methionine residue in a voltage-dependent potassium channel modulates its inactivation. When this methionine residue is oxidized to methionine sulfoxide, the inactivation is disrupted, and it is reversed by coexpression with peptide methionine sulfoxide reductase. The results suggest that oxidation and reduction of methionine could play a dynamic role in the cellular signal transduction process in a variety of systems.
蛋白质中氨基酸残基的氧化可由细胞通常产生的多种氧化剂引起。蛋白质中的甲硫氨酸氧化为甲硫氨酸亚砜与衰老以及病理状况有关,并且这是一个由一种普遍存在的酶——肽甲硫氨酸亚砜还原酶介导的可逆反应。甲硫氨酸氧化的可逆性表明它可能作为一种细胞调节机制,尽管尚未证明有这种体内活性。我们在此表明,电压依赖性钾通道中甲硫氨酸残基的氧化会调节其失活。当这个甲硫氨酸残基氧化为甲硫氨酸亚砜时,失活被破坏,并且通过与肽甲硫氨酸亚砜还原酶共表达可使其逆转。结果表明,甲硫氨酸的氧化和还原可能在多种系统的细胞信号转导过程中发挥动态作用。