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Structural basis for brassinosteroid response by BIL1/BZR1


BRZ-INSENSITIVE-LONG HYPOCOTYL 1 (BIL1)/BRASSINAZOLE-RESISTANT 1 (BZR1) is a master transcription factor of brassinosteroid (BR) signalling. The varieties of nucleobase recognition of the NN-BRRE-core motif (NNCGTG), one of variant G-box motifs, distinguish BIL1/BZR1 from basic helix-loop-helix transcription factors, underlying the specific regulation of BR-responsive genes. Here, we show the non-canonical bHLH dimer formation of BIL1/BZR1 to optimize the interaction network with DNA and the orientation of a key residue for NN-BRRE-core motif recognition.

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Figure 1: Characterization and structure of the BIL1/BZR1 DBD.
Figure 2: DNA binding mode of BIL1/BZR1.

Data availability

The atomic coordinates and structural factors are available from the PDB under accession code 5ZD4 for the mutant MBP-fused BIL1/BZR1-DNA complex. The other data that support the findings of this study are available from the corresponding author on request.


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The synchrotron-radiation experiments were performed on beamlines AR NE3A at the Photon Factory with the approval of the High Energy Accelerator Research Organization (Proposal No. 2016G648). This work was supported by a Grant-in-Aid for Scientific Research on Innovative Areas No. 17H05835 from the Japan Society for the Promotion of Science (JSPS) (T.M.), the Platform for Drug Discovery, Informatics, and Structural Life Science from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) (M.T.), the Basis for Supporting Innovative Drug Discovery and Life Science Research from the MEXT (T.M.), and the Core Research for Evolutional Science and Technology (CREST) Program of Japan Science and Technology Agency (JST) (T.A. and T.N.).

Author information




M.T. conceived and designed the research. S.N., T.M., Y.X. and A.N. performed the biochemical experiments and collected X-ray diffraction data. S.N., T.M., Y.X., A.N. and K.H. analysed the data. S.N., T.M., T.A., T.N. and M.T. wrote the paper. M.T. edited the manuscript.

Corresponding author

Correspondence to Masaru Tanokura.

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The authors declare no competing interests.

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Supplementary Information

Supplementary Tables 1–3, Supplementary Figures 1–12, Supplementary References

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Nosaki, S., Miyakawa, T., Xu, Y. et al. Structural basis for brassinosteroid response by BIL1/BZR1. Nature Plants 4, 771–776 (2018).

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