1. Oxidation of methionine residues: the missing link between stress and signalling responses in plants
- Author
-
Michael J. Emes
- Subjects
inorganic chemicals ,PMSR, peptide methionine sulfoxide reductase ,calcium-dependent protein kinase (CDPK) ,ACS, 1-amino-cyclopropane-1-carboxylate synthase ,MALDI–TOF-MS, matrix-assisted laser-desorption ionization–time-of-flight MS ,Biology ,SPS, sucrose-phosphate synthase ,Biochemistry ,methionine oxidation ,chemistry.chemical_compound ,Methionine ,ROS, reactive oxygen species ,Met, methionine ,Protein phosphorylation ,ASK1 ,MetSO, methionine sulfoxide ,SnRK1, SNF1-related protein kinase ,Protein kinase A ,Molecular Biology ,phosphorylation motif ,Kinase ,PP1α, protein phosphatase 1α ,Cell Biology ,Autophagy-related protein 13 ,Plants ,pSer, phosphoserine ,NR, nitrate reductase ,Oxidative Stress ,AMPK, AMP-activated protein kinase ,chemistry ,DTT, dithiothreitol ,hydrogen peroxide (H2O2) ,oxidative signalling ,Methionine sulfoxide reductase ,Phosphorylation ,CDPK, calcium-dependent protein kinase ,Oxidation-Reduction ,MAPK, mitogen-activated protein kinase ,Signal Transduction ,Research Article - Abstract
The mechanisms involved in sensing oxidative signalling molecules, such as H2O2, in plant and animal cells are not completely understood. In the present study, we tested the postulate that oxidation of Met (methionine) to MetSO (Met sulfoxide) can couple oxidative signals to changes in protein phosphorylation. We demonstrate that when a Met residue functions as a hydrophobic recognition element within a phosphorylation motif, its oxidation can strongly inhibit peptide phosphorylation in vitro. This is shown to occur with recombinant soybean CDPKs (calcium-dependent protein kinases) and human AMPK (AMP-dependent protein kinase). To determine whether this effect may occur in vivo, we monitored the phosphorylation status of Arabidopsis leaf NR (nitrate reductase) on Ser534 using modification-specific antibodies. NR was a candidate protein for this mechanism because Met538, located at the P+4 position, serves as a hydrophobic recognition element for phosphorylation of Ser534 and its oxidation substantially inhibits phosphorylation of Ser534 in vitro. Two lines of evidence suggest that Met oxidation may inhibit phosphorylation of NR-Ser534 in vivo. First, phosphorylation of NR at the Ser534 site was sensitive to exogenous H2O2 and secondly, phosphorylation in normal darkened leaves was increased by overexpression of the cytosolic MetSO-repair enzyme PMSRA3 (peptide MetSO reductase A3). These results are consistent with the notion that oxidation of surface-exposed Met residues in kinase substrate proteins, such as NR, can inhibit the phosphorylation of nearby sites and thereby couple oxidative signals to changes in protein phosphorylation.
- Published
- 2009