Letter | Published:

Allosteric receptor activation by the plant peptide hormone phytosulfokine

Nature volume 525, pages 265268 (10 September 2015) | Download Citation

Abstract

Phytosulfokine (PSK) is a disulfated pentapeptide that has a ubiquitous role in plant growth and development1,2. PSK is perceived by its receptor PSKR3,4, a leucine-rich repeat receptor kinase (LRR-RK). The mechanisms underlying the recognition of PSK, the activation of PSKR and the identity of the components downstream of the initial binding remain elusive. Here we report the crystal structures of the extracellular LRR domain of PSKR in free, PSK- and co-receptor-bound forms. The structures reveal that PSK interacts mainly with a β-strand from the island domain of PSKR, forming an anti-β-sheet. The two sulfate moieties of PSK interact directly with PSKR, sensitizing PSKR recognition of PSK. Supported by biochemical, structural and genetic evidence, PSK binding enhances PSKR heterodimerization with the somatic embryogenesis receptor-like kinases (SERKs). However, PSK is not directly involved in PSKR–SERK interaction but stabilizes PSKR island domain for recruitment of a SERK. Our data reveal the structural basis for PSKR recognition of PSK and allosteric activation of PSKR by PSK, opening up new avenues for the design of PSKR-specific small molecules.

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Acknowledgements

We thank S. Huang and J. He for assistance with data collection, J. Li for the serk1, serk2, bak1 single and triple mutant seeds and W. Li and W. Chu for providing facility support. This research was funded by Projects of International Cooperation and Exchanges NSFC (31420103906), Chinese Ministry of Science and Technology (2015CB910200) and State Key Program of National Natural Science of China (31130063) to J.C.; Chinese Natural Science Foundation (31330053) to W.Y. and Ministry of Science and Technology of China (2015CB910202) to H.L.

Author information

Author notes

    • Jizong Wang
    •  & Hongju Li

    These authors contributed equally to this work.

Affiliations

  1. Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China

    • Jizong Wang
    • , Zhifu Han
    • , Heqiao Zhang
    • , Guangzhong Lin
    •  & Jijie Chai
  2. State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China

    • Hongju Li
    • , Tong Wang
    •  & Weicai Yang
  3. School of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China

    • Junbiao Chang

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Contributions

J.C., W.Y., J.W., H.L. and Z.H. designed the experiments. J.W., H.L., H.Z., T.W. and G.L. performed the experiments. Data were analysed by J.C., W.Y., J.W., H.L. and J.C.; J.C., W.Y., J.W., H.L. and Z.H. contributed to manuscript preparation. J.C. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Weicai Yang or Jijie Chai.

The atomic coordinates and structure factors have been deposited in the Protein Data Bank. The PDB code of free DcPSKRLRR is 4Z62. The PDB codes of PSK–PSKR1LRR and PSK–DcPSKRLRR are 4Z63 and 4Z5W, respectively. The PDB codes of PSK–PSKR1LRR–SERK1LRR and PSK–DcPSKRLRR–SERK2LRR are 4Z64 and 4Z61, respectively.

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    Supplementary Data

    This file contains the full blots for figures 2c, 2d, 4c and 4e.

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DOI

https://doi.org/10.1038/nature14858

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