14-3-3是高度保守的磷酸肽结合蛋白,在植物的各种发育和信号通路中起重要作用。然而,尽管蛋白质磷酸化已被证明是调节光信号通路许多关键成分的关键机制,14-3-3蛋白在光形态发生中的作用仍然很模糊。植物铬相互作用因子3(PIF3)是一种广泛研究的抑制光形态发生的转录因子,众所周知,在红色(R)光照射下,光活化的植物色素B(phyB)与PIF3相互作用并诱导其快速磷酸化和降解。光调节蛋白激酶(PPKs),一个核蛋白激酶家族,在R光中与phyB和PIF3相互作用,并在体内介导PIF3的多位点磷酸化。这里,我们报道了14-3-3蛋白家族的两个成员,14-3-3λ和κ,与PIF3的bHLH结构域中的丝氨酸残基结合,该残基可以被PPKs磷酸化,并充当R光诱导的光形态发生的关键正调节剂。此外,14-3-3λ和κ优先与光活化的phyB相互作用,促进phyB-PIF3-PPK复合物的形成,从而在R光暴露时促进phyB诱导的PIF3的磷酸化和降解。一起,我们的数据表明,14-3-3λ和κ与phyB-PIF3模块紧密合作,以调节拟南芥中的光信号传导。
14-3-3s are highly conserved phosphopeptide-binding proteins that play important roles in various developmental and signaling pathways in plants. However, although protein phosphorylation has been proven to be a key mechanism for regulating many pivotal components of the light signaling pathway, the role of 14-3-3 proteins in photomorphogenesis remains largely obscure. PHYTOCHROME-INTERACTING FACTOR3 (PIF3) is an extensively studied transcription factor repressing photomorphogenesis, and it is well-established that upon red (R) light exposure, photo-activated phytochrome B (phyB) interacts with PIF3 and induces its rapid phosphorylation and degradation. PHOTOREGULATORY PROTEIN KINASES (PPKs), a family of nuclear protein kinases, interact with phyB and
PIF3 in R light and mediate multisite phosphorylation of
PIF3 in vivo. Here, we report that two members of the 14-3-3 protein family, 14-3-3λ and κ, bind to a serine residue in the bHLH domain of PIF3 that can be phosphorylated by PPKs, and act as key positive regulators of R light-induced photomorphogenesis. Moreover, 14-3-3λ and κ preferentially interact with photo-activated phyB and promote the phyB-
PIF3-PPK complex formation, thereby facilitating phyB-induced phosphorylation and degradation of
PIF3 upon R light exposure. Together, our data demonstrate that 14-3-3λ and κ work in close concert with the phyB-
PIF3 module to regulate light signaling in Arabidopsis.