Department of Biochemistry and Cell Biology, MFPL, University of Vienna, Dr. Bohrgasse 9, A-1030, Vienna, Austria.
J Exp Bot. 2012 Feb;63(4):1725-33. doi: 10.1093/jxb/err403. Epub 2011 Dec 22.
The role of protein phosphorylation for adjusting chloroplast functions to changing environmental needs is well established, whereas calcium signalling in the chloroplast is only recently becoming appreciated. The work presented here explores the potential cross-talk between calcium signalling and protein phosphorylation in chloroplasts and provides the first evidence for targets of calcium-dependent protein phosphorylation at the thylakoid membrane. Thylakoid proteins were screened for calcium-dependent phosphorylation by 2D gel electrophoresis combined with phospho-specific labelling and PsaN, CAS, and VAR1, among other proteins, were identified repeatedly by mass spectrometry. Subsequently their calcium-dependent phosphorylation was confirmed in kinase assays using the purified proteins and chloroplast extracts. This is the first report on the protein targets of calcium-dependent phosphorylation of thylakoid proteins and provides ground for further studies in this direction.
蛋白质磷酸化在调节叶绿体功能以适应不断变化的环境需求方面的作用已得到充分证实，而叶绿体中的钙信号转导最近才受到重视。这里介绍的工作探讨了钙信号转导与叶绿体中蛋白质磷酸化之间的潜在串扰，并为类囊体膜上钙依赖性蛋白质磷酸化的靶标提供了首个证据。通过二维凝胶电泳结合磷酸特异性标记筛选了对钙依赖性磷酸化的类囊体蛋白，通过质谱鉴定了 PsaN、CAS 和 VAR1 等多种蛋白质，随后使用纯化蛋白和叶绿体提取物在激酶测定中证实了它们的钙依赖性磷酸化。这是关于类囊体蛋白钙依赖性磷酸化的蛋白质靶标的首次报道，为进一步的研究提供了依据。
