Wang Qin, Barshop William D, Bian Mingdi, Vashisht Ajay A, He Reqing, Yu Xuhong, Liu Bin, Nguyen Paula, Liu Xuanming, Zhao Xiaoying, Wohlschlegel James A, Lin Chentao
Basic Forestry and Proteomics Research Center, Fujian Agriculture and Forestry University, Fuzhou, China; Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China; Department of Molecular, Cell & Developmental Biology, University of California, Los Angeles, CA 90095, USA.
Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA.
Mol Plant. 2015 Apr;8(4):631-43. doi: 10.1016/j.molp.2015.03.005. Epub 2015 Mar 17.
Arabidopsis cryptochrome 2 (CRY2) is a blue light receptor that mediates light inhibition of hypocotyl elongation and long-day promotion of floral initiation. CRY2 is known to undergo blue light-dependent phosphorylation, which is believed to serve regulatory roles in the function of CRY2. We report here on a biochemical and genetics study of CRY2 phosphorylation. Using mass spectrometry analysis, we identified three serine residues in the CCE domain of CRY2 (S598, S599, and S605) that undergo blue light-dependent phosphorylation in Arabidopsis seedlings. A study of serine-substitution mutations in the CCE domain of CRY2 demonstrates that CRY2 contains two types of phosphorylation in the CCE domain, one in the serine cluster that causes electrophoretic mobility upshift and the other outside the serine cluster that does not seem to cause mobility upshift. We showed that mutations in the serine residues within and outside the serine cluster diminished blue light-dependent CRY2 phosphorylation, degradation, and physiological activities. These results support the hypothesis that blue light-dependent phosphorylation of the CCE domain determines the photosensitivity of Arabidopsis CRY2.
拟南芥隐花色素2（CRY2）是一种蓝光受体，可介导光对下胚轴伸长的抑制以及长日照对开花起始的促进作用。已知CRY2会发生蓝光依赖的磷酸化，据信这在CRY2的功能中起调节作用。我们在此报告一项关于CRY2磷酸化的生化和遗传学研究。通过质谱分析，我们在拟南芥幼苗中鉴定出CRY2的CCE结构域中的三个丝氨酸残基（S598、S599和S605）会发生蓝光依赖的磷酸化。对CRY2的CCE结构域中的丝氨酸替代突变的研究表明，CRY2在CCE结构域中包含两种类型的磷酸化，一种在丝氨酸簇中，会导致电泳迁移率上移，另一种在丝氨酸簇之外，似乎不会导致迁移率上移。我们表明，丝氨酸簇内外的丝氨酸残基发生突变会减少蓝光依赖的CRY2磷酸化、降解和生理活性。这些结果支持了CCE结构域的蓝光依赖磷酸化决定拟南芥CRY2光敏性的假说。
