J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (3): 731-740.DOI: 10.1111/jipb.13223

• Plant Reproduction Biology • Previous Articles     Next Articles

Molecular basis of CONSTANS oligomerization in FLOWERING LOCUS T activation

Xiaolin Zeng1,2†, Xinchen Lv2,3†, Rui Liu3†, Hang He3, Shiqi Liang3, Lixian Chen3, Fan Zhang3, Liu Chen3, Yuehui He1,2,4* and Jiamu Du3*   

  1. 1 Peking‐Tsinghua Center for Life Sciences, School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
    2 National Key Laboratory of Plant Molecular Genetics & Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai 201602, China
    3 Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
    4 Peking University Institute of Advanced Agricultural Sciences, Weifang 261000, China

    These authors contributed equally to this work.
    *Correspondences: Yuehui He (yhhe@pku.edu.cn); Jiamu Du (dujm@sustech.edu.cn, Dr. Du is responsible for the distribution of the materials associated with this article)
  • Received:2021-09-26 Accepted:2022-01-10 Online:2022-01-13 Published:2022-03-01


The transcription factor CONSTANS (CO) integrates day-length information to induce the expression of florigen FLOWERING LOCUS T (FT) in Arabidopsis. We recently reported that the C-terminal CCT domain of CO forms a complex with NUCLEAR FACTOR-YB/YC to recognize multiple cis-elements in the FT promoter, and the N-terminal tandem B-box domains form a homomultimeric assembly. However, the mechanism and biological function of CO multimerization remained unclear. Here, we report that CO takes on a head-to-tail oligomeric configuration via its B-boxes to mediate FT activation in long days. The crystal structure of B-boxesCO reveals a closely connected tandem B-box fold forming a continuous head-to-tail assembly through unique CDHH zinc fingers. Mutating the key residues involved in CO oligomerization resulted in a non-functional CO, as evidenced by the inability to rescue co mutants. By contrast, a transgene encoding a human p53-derived tetrameric peptide in place of the B-boxesCO rescued co mutant, emphasizing the essential role of B-boxesCO-mediated oligomerization. Furthermore, we found that the four TGTG-bearing cis-elements in FT proximal promoter are required for FT activation in long days. Our results suggest that CO forms a multimer to bind to the four TGTG motifs in the FT promoter to mediate FT activation.

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