Structural insights into brassinosteroid export mediated by the Arabidopsis ABC transporter ABCB1
Brassinosteroids (BRs) are steroidal phytohormones indispensable for plant growth, development, and responses to environmental stresses. The export of bioactive BRs to the apoplast is essential for BR signaling initiation, which requires binding of a BR molecule to the extracellular domains of the plasma membrane-localized receptor complex. We have previously shown that the Arabidopsis thaliana ATP-binding cassette (ABC) transporter ABCB19 functions as a BR exporter and, together with its close homolog ABCB1, positively regulates BR signaling. Here, we demonstrate that ABCB1 is another BR transporter. The ATP hydrolysis activity of ABCB1 can be stimulated by bioactive BRs, and its transport activity was confirmed in proteoliposomes and protoplasts. Structures of ABCB1 were determined in substrate-unbound (apo), brassinolide (BL)-bound, and ATP plus BL-bound states. In the BL-bound structure, BL is bound to the hydrophobic cavity formed by the transmembrane domain and triggers local conformational changes. Together, our data provide additional insights into ABC transporter-mediated BR export.
Authors
- Linfeng Sun (ORCID: https://orcid.org/0000-0001-9367-2444)
- Miroslav Kvasnica (ORCID: https://orcid.org/0000-0002-0597-3261)
- Jiřı́ Friml (ORCID: https://orcid.org/0000-0002-8302-7596)
- Eugenia Russinova (ORCID: https://orcid.org/0000-0002-0569-1977)
- Hilde Janssens (ORCID: https://orcid.org/0000-0001-6764-7181)
- Johan M. Winne (ORCID: https://orcid.org/0000-0002-9015-4497)
- Shutang Tan (ORCID: https://orcid.org/0000-0002-0471-8285)
- Wei Ying (ORCID: https://orcid.org/0000-0002-6373-9115)
- Xin Liu (ORCID: https://orcid.org/0000-0002-8368-4369)
- Qian Ma (ORCID: https://orcid.org/0000-0001-8718-0005)
- Hong Wei (ORCID: https://orcid.org/0009-0001-8181-9004)
- Heyuan Zhu
- Yongxiang Gao (ORCID: https://orcid.org/0000-0003-1214-889X)
Institutions
- University of Science and Technology of China (CN)
- Institute of Science and Technology Austria (AT)
- Ghent University (BE)
- VIB-UGent Center for Plant Systems Biology (BE)
- Hefei National Center for Physical Sciences at Nanoscale (CN)
- Czech Academy of Sciences, Institute of Experimental Botany (CZ)
- Palacký University Olomouc (CZ)
Publication Details
- Journal
- Plant Communications
- Published
- 2024-11-04
- DOI
- https://doi.org/10.1016/j.xplc.2024.101181
- Citations
- 17
- Primary Topic
- Plant Molecular Biology Research
- Type
- article
- Field-Weighted Citation Impact
- 10.19
Funders
- Cyrus Tang Foundation
- National Natural Science Foundation of China
- Chinese Academy of Sciences
- Fonds Wetenschappelijk Onderzoek
- University of Science and Technology of China
- Vlaamse regering
- Natural Science Foundation of Anhui Province
- Fundamental Research Funds for the Central Universities