Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 61186, Korea.
Int J Mol Sci. 2019 Jul 13;20(14):3450. doi: 10.3390/ijms20143450.
Extensive research over several decades in plant light signaling mediated by photoreceptors has identified the molecular mechanisms for how phytochromes regulate photomorphogenic development, which includes degradation of phytochrome-interacting factors (PIFs) and inactivation of COP1-SPA complexes with the accumulation of master transcription factors for photomorphogenesis, such as HY5. However, the initial biochemical mechanism for the function of phytochromes has not been fully elucidated. Plant phytochromes have long been known as phosphoproteins, and a few protein phosphatases that directly interact with and dephosphorylate phytochromes have been identified. However, there is no report thus far of a protein kinase that acts on phytochromes. On the other hand, plant phytochromes have been suggested as autophosphorylating serine/threonine protein kinases, proposing that the kinase activity might be important for their functions. Indeed, the autophosphorylation of phytochromes has been reported to play an important role in the regulation of plant light signaling. More recently, evidence that phytochromes function as protein kinases in plant light signaling has been provided using phytochrome mutants displaying reduced kinase activities. In this review, we highlight recent advances in the reversible phosphorylation of phytochromes and their functions as protein kinases in plant light signaling.
几十年来，对植物光信号转导中介导的光受体的广泛研究已经确定了植物色素如何调节光形态发生发育的分子机制，包括植物色素相互作用因子（PIFs）的降解和 COP1-SPA 复合物的失活，同时积累光形态发生的主转录因子，如 HY5。然而，植物色素功能的初始生化机制尚未完全阐明。植物色素长期以来一直被认为是磷酸化蛋白，已经鉴定出一些与植物色素直接相互作用并去磷酸化的蛋白磷酸酶。然而，迄今为止还没有报道一种作用于植物色素的蛋白激酶。另一方面，植物色素被认为是自磷酸化丝氨酸/苏氨酸蛋白激酶，这表明激酶活性可能对其功能很重要。事实上，已经报道植物色素的自磷酸化在植物光信号转导的调控中起着重要作用。最近，使用显示激酶活性降低的植物色素突变体，提供了植物光信号转导中植物色素作为蛋白激酶的功能的证据。在这篇综述中，我们强调了植物色素可逆磷酸化及其作为蛋白激酶在植物光信号转导中的功能的最新进展。
