Section of Molecular Cell and Developmental Biology and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX, USA.
Plant Signal Behav. 2011 Aug;6(8):1119-21. doi: 10.4161/psb.6.8.16049. Epub 2011 Aug 1.
Phytochrome (phy) family of photoreceptors is a broad sensor of environmental light signals that promote photomorphogenic development of plants. Phytochrome Interacting Factors (PIFs), bHLH family of transcription factors, repress photomorphogenesis in the dark in an overlapping manner. Phytochromes interact with PIFs in response to light and induce rapid phosphorylation, poly-ubiquitylation and degradation of PIFs through the ubiquitin/26S proteasome pathway to promote photomorphogenesis. Structure-function analyses with PIF family members revealed that multiple domains are necessary for the light-induced phosphorylation and degradation of PIFs. CK2, a ubiquitious Ser/Thr kinase, phosphorylates PIF1 independent of light. In addition, PIF1 mutants deficient in CK2 phosphorylation sites are still robustly phosphorylated but not efficiently degraded in response to light. These data suggest that multiple kinases phosphorylate PIF1 to promote light-induced degradation and photomorphogenesis.
植物光敏色素（phy）家族是环境光信号的广泛传感器，促进植物的光形态建成发育。光敏色素相互作用因子（PIFs）是 bHLH 转录因子家族，以重叠的方式在黑暗中抑制光形态建成。光敏色素与 PIFs 相互作用以响应光，并通过泛素/26S 蛋白酶体途径诱导 PIFs 的快速磷酸化、多泛素化和降解，以促进光形态建成。对 PIF 家族成员的结构-功能分析表明，多个结构域对于光诱导的 PIF 磷酸化和降解是必要的。CK2 是一种普遍存在的 Ser/Thr 激酶，可独立于光对 PIF1 进行磷酸化。此外，CK2 磷酸化位点缺失的 PIF1 突变体仍能被强烈磷酸化，但在光下不能有效降解。这些数据表明，多种激酶磷酸化 PIF1 以促进光诱导的降解和光形态建成。
