Laboratory of Plant Stress Biology, Department of Biology, Henan University, Kaifeng, China.
Plant Signal Behav. 2011 Jun;6(6):889-91. doi: 10.4161/psb.6.6.15308. Epub 2011 Jun 1.
Nitrate reductase is a central enzyme of nitrogen assimilation in plants. In a recent work, we have revealed MPK6 could phosphorylate Arabidopsis NIA2 at the serine 627 in hinge 2 region, this phosporylation may represent a rapid activation mechnism when plant need excessive nitrate reduction. Interestingly, all eukaryotic NRs have conserved docking sequence in their FAD domains, and many plant NR proteins have the conserved MAPK phosphorylation site. Those results indicated the MAPK cascades, the conserved signaling pathway also involved in lateral root development, mediated of NR phosporylation and NO generation. We noticed that the phosphorylation of S627 residue by MPK6 have a specially influence on the NO generation activity of NIA2. Although no homology of mammalian NOS has been identified in plants, NR may still share a similar regulation mechanism with mammalian NOS.
硝酸还原酶是植物氮同化过程中的一种关键酶。在最近的一项研究中，我们揭示了 MPK6 可以在 hinge 2 区域的丝氨酸 627 处磷酸化拟南芥 NIA2，这种磷酸化可能代表了植物需要过量硝酸盐还原时的一种快速激活机制。有趣的是，所有真核生物的 NR 都在其 FAD 结构域中具有保守的对接序列，并且许多植物 NR 蛋白具有保守的 MAPK 磷酸化位点。这些结果表明，MAPK 级联途径，即参与侧根发育的保守信号通路，也介导了 NR 的磷酸化和 NO 的产生。我们注意到，MPK6 对 S627 残基的磷酸化对 NIA2 的 NO 生成活性有特殊影响。尽管在植物中尚未鉴定出与哺乳动物 NOS 同源的物质，但 NR 可能仍然与哺乳动物 NOS 具有相似的调节机制。
