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. 2024 Sep 16:S0092-8674(24)01023-7.
doi: 10.1016/j.cell.2024.09.005. Online ahead of print.

Light-induced remodeling of phytochrome B enables signal transduction by phytochrome-interacting factor

Zhengdong Wang  1 , Wenfeng Wang  2 , Didi Zhao  2 , Yanping Song  1 , Xiaoli Lin  2 , Meng Shen  3 , Cheng Chi  2 , Bin Xu  2 , Jun Zhao  2 , Xing Wang Deng  4 , Jizong Wang  5
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Free article

Light-induced remodeling of phytochrome B enables signal transduction by phytochrome-interacting factor

Zhengdong Wang et al. Cell. .
Free article

Abstract

Phytochrome B (phyB) and phytochrome-interacting factors (PIFs) constitute a well-established signaling module critical for plants adapting to ambient light. However, mechanisms underlying phyB photoactivation and PIF binding for signal transduction remain elusive. Here, we report the cryo-electron microscopy (cryo-EM) structures of the photoactivated phyB or the constitutively active phyBY276H mutant in complex with PIF6, revealing a similar trimer. The light-induced configuration switch of the chromophore drives a conformational transition of the nearby tongue signature within the phytochrome-specific (PHY) domain of phyB. The resulting α-helical PHY tongue further disrupts the head-to-tail dimer of phyB in the dark-adapted state. These structural remodelings of phyB facilitate the induced-fit recognition of PIF6, consequently stabilizing the N-terminal extension domain and a head-to-head dimer of activated phyB. Interestingly, the phyB dimer exhibits slight asymmetry, resulting in the binding of only one PIF6 molecule. Overall, our findings solve a key question with respect to how light-induced remodeling of phyB enables PIF signaling in phytochrome research.

Keywords: photoactivation; phytochrome B; phytochrome-interacting factors; signal transduction.

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Conflict of interest statement

Declaration of interests The authors declare no competing interests.

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