Center for Plant Molecular Biology (ZMBP) - Plant Physiology, University of Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany.
Eur J Cell Biol. 2010 Feb-Mar;89(2-3):175-83. doi: 10.1016/j.ejcb.2009.11.023. Epub 2010 Jan 4.
Reversible phosphorylation plays a crucial role in regulating the activity of enzymes and other proteins in all living organisms. Particularly, the phosphorylation of transcription factors can modulate their capability to regulate downstream target genes. In plants, basic domain-containing leucine-zipper (bZIP) transcription factors have an important function in the regulation of many developmental processes and adaptive responses to the environment. By a comprehensive sequence analysis, we identified a set of highly conserved, potentially phospho-accepting serines within the DNA-binding domain of plant bZIPs. Structural modelling revealed that these serines are in physical contact with the DNA and predicts that their phosphorylation will have a major influence on the DNA-binding activity of plant bZIPs. In support of this, we show, by means of a quantitative in vitro binding assay, that phosphorylation-mimicking substitutions of some of these serines strongly interfere with the DNA binding of two prototypical Arabidopsis bZIPs, namely AtZIP63 and HY5. Our data suggest that the identified serines could serve as in vivo targets for kinases and phosphatases, allowing the fine-tuning of bZIP factor activity at the DNA-protein interaction level.
可逆磷酸化在调节所有生物体内酶和其他蛋白质的活性方面起着至关重要的作用。特别是，转录因子的磷酸化可以调节它们调节下游靶基因的能力。在植物中，碱性亮氨酸拉链(bZIP)转录因子在许多发育过程的调节和对环境的适应性反应中具有重要功能。通过全面的序列分析，我们在植物 bZIP 的 DNA 结合域中鉴定出一组高度保守的、潜在的磷酸化接受丝氨酸。结构建模表明，这些丝氨酸与 DNA 直接接触，并预测它们的磷酸化将对植物 bZIP 的 DNA 结合活性产生重大影响。为了支持这一点，我们通过定量体外结合测定表明，这些丝氨酸中的一些磷酸化模拟取代强烈干扰了两个拟南芥 bZIP 原型蛋白 AtZIP63 和 HY5 的 DNA 结合。我们的数据表明，鉴定出的丝氨酸可以作为激酶和磷酸酶的体内靶标，允许在 DNA-蛋白相互作用水平上精细调节 bZIP 因子的活性。
