14-3-3 proteins regulate photomorphogenesis by facilitating light-induced degradation of PIF3.

Pengyu Song, Zidan Yang, Can Guo, Run Han, Huaichang Wang, Jie Dong, Dingming Kang, Yan Guo, Shuhua Yang, Jigang Li

The New phytologist 2023 Jan

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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. © 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.

Citation

Pengyu Song, Zidan Yang, Can Guo, Run Han, Huaichang Wang, Jie Dong, Dingming Kang, Yan Guo, Shuhua Yang, Jigang Li. 14-3-3 proteins regulate photomorphogenesis by facilitating light-induced degradation of PIF3. The New phytologist. 2023 Jan;237(1):140-159