Abstract
The plant aluminum (Al)-activated malate transporter ALMT1 mediates the efflux of malate to chelate the Al in acidic soils and underlies the plant Al resistance. Here we present cryo-electron microscopy (cryo-EM) structures of Arabidopsis thaliana ALMT1 (AtALMT1) in the apo, malate-bound, and Al-bound states at neutral and/or acidic pH at up to 3.0 Å resolution. The AtALMT1 dimer assembles an anion channel and each subunit contains six transmembrane helices (TMs) and six cytosolic α-helices. Two pairs of Arg residues are located in the center of the channel pore and contribute to malate recognition. Al binds at the extracellular side of AtALMT1 and induces conformational changes of the TM1–2 loop and the TM5–6 loop, resulting in the opening of the extracellular gate. These structures, along with electrophysiological measurements, molecular dynamic simulations, and mutagenesis study in Arabidopsis, elucidate the structural basis for Al-activated malate transport by ALMT1.
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Data availability
The cryo-EM density maps and coordinates of ALMT1apo/pH5, ALMT1apo/pH7.5, ALMT1malate/pH7.5, ALMT1Al/pH5, and ALMT1M60A/Al/pH5 have been deposited in the Electron Microscopy Data Bank (EMDB) under accession numbers EMD-32084, EMD-32085, EMD-32086, EMD-32087, and EMD-32050, and in the RCSB Protein Data Bank (PDB) under accession codes 7VQ3, 7VQ4, 7VQ5, 7VQ7, and 7VOJ.
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Acknowledgements
Single-particle cryo-EM data were collected at the Center of Cryo-Electron Microscopy at Zhejiang University. We thank Dr. Xing Zhang and Dr. Shenghai Chang for support in facility access and data acquisition. We thank Dr. Chao Feng Huang for kindly providing the almt1 mutant seeds. We thank Dr. Nam Nguyen for his assistance in the paper preparation. This work was supported in part by the Ministry of Science and Technology (2020YFA0908501 and 2018YFA0508100 to J.G., 2016YFA0501100 to X.Z.), the National Natural Science Foundation of China (31870724 to J.G., 82030108, 31872796 and 81571127 to W.Y., 31730006 to S.J.Z., and 31600606 to X.Z.), National Major Special Project on New Drug Innovation of China (2018ZX09711001-004-005 to W.Y.), Zhejiang Provincial Natural Science Foundation (LR19C050002 to J.G., LR16H090001 to W.Y.), and the Fundamental Research Funds for the Central Universities (2021FZZX001-28 to J.G. and S.J.Z.). J.G. is supported by MOE Frontier Science Center for Brain Science & Brain-Machine Integration, Zhejiang University. X.Z. is supported by Guangdong Provincial Key Laboratory of Brain Connectome and Behavior (2017B030301017) and CAS Key Laboratory of Brain Connectome and Manipulation (2019DP173024).
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J.G., W.Y., and S.J.Z. conceived and supervised the project. J.W., X.Z., Y.X., and X.L. prepared the samples, performed data acquisition, structure determination, and data analysis. X.Y. and Y.L. performed electrophysiological studies. Z.J.D. and T.Y. performed the in vivo mutagenesis studies. X.X. performed molecular dynamics simulation. All authors participated in the data analysis and paper preparation.
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Wang, J., Yu, X., Ding, Z.J. et al. Structural basis of ALMT1-mediated aluminum resistance in Arabidopsis. Cell Res 32, 89–98 (2022). https://doi.org/10.1038/s41422-021-00587-6
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DOI: https://doi.org/10.1038/s41422-021-00587-6
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