The ectopic expression of methionine sulfoxide reductase 4 results in enhanced growth performance in arabidopsis

In response to challenging oxidative environments, most aerobic organisms have developed cellular defense systems that either repair or degrade damaged proteins to prevent them from adversely affecting cellular reactions. For instance, oxidized methionine can be reduced to methionine by the enzyme methionine sulfoxide reductase (MSR). Previously, we reported that the Arabidopsis gene MSR4 (AT4G25130) is induced by salt stress, and during our investigations into this gene, we generated a transgenic Arabidopsis that overexpressed a mutant form of MSR4 (mMSR4). The transgenic plants exhibited enhanced sensitivity to high salt stress. Consistent with this observation, the ectopic expression of MSR4 enhanced growth performance in normal as well as in stress medium. To determine the targets of MSR4, we performed two-dimensional electrophoresis analyses and observed a significant reduction in the levels of chloroplast heat shock proteins, which may explain the enhanced salt stress sensitivity of mMSR4 transgenic plants.