Coupling oxidative signals to protein phosphorylation via methionine oxidation in Arabidopsis.
Coupling oxidative signals to protein phosphorylation via methionine oxidation in Arabidopsis.
复制标题
通过拟南芥中的蛋氨酸氧化，将氧化信号与蛋白质磷酸化偶联。
DOI：
10.1042/bj20090764
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发表时间：
2009-08-13
期刊：
影响因子：
--
通讯作者：
Huber SC
中科院分区：
文献类型：
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作者：
Hardin SC;Larue CT;Oh MH;Jain V;Huber SC
在植物和动物细胞中，参与感知氧化信号分子（如H2 O2）的机制尚未完全了解。在本研究中，我们测试的假设，氧化蛋氨酸（蛋氨酸）MetSO（蛋氨酸亚砜）可以耦合氧化信号的蛋白质磷酸化的变化。我们证明，当Met残基作为磷酸化基序内的疏水识别元件时，其氧化可以强烈抑制体外肽磷酸化。这表明重组大豆CDPKs（钙依赖性蛋白激酶）和人AMPK（AMP依赖性蛋白激酶）会发生。为了确定这种影响是否可能发生在体内，我们监测的磷酸化状态的拟南芥叶NR（硝酸还原酶）Ser 534使用修饰特异性抗体。NR是该机制的候选蛋白，因为位于P+4位置的Met 538充当Ser 534磷酸化的疏水识别元件，并且其氧化在体外基本上抑制Ser 534的磷酸化。两条证据表明，Met氧化可以抑制体内NR-Ser 534的磷酸化。首先，NR在Ser 534位点的磷酸化对外源性H2 O2敏感，其次，在正常变暗的叶片中的磷酸化通过过表达胞质MetSO修复酶PMSRA 3（肽MetSO还原酶A3）而增加。这些结果与激酶底物蛋白（如NR）中表面暴露的Met残基的氧化可以抑制附近位点的磷酸化，从而将氧化信号与蛋白磷酸化的变化偶联的观点一致。
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.