| Structural highlights
Function
ALMT1_ARATH Malate transporter critical for aluminum tolerance. The STOP1 transcription factor is required for ALMT1 expression.[1] [2] [3] [4]
Publication Abstract from PubMed
In plant cells, ALMTs are key plasma and vacuolar membrane-localized anion channels regulating plant responses to the environment. Vacuolar ALMTs control anion accumulation in plant cells and, in guard cells, they regulate stomata aperture. The activation of vacuolar ALMTs depends on voltage and cytosolic malate, but the underlying molecular mechanisms remain elusive. Here we report the cryo-EM structures of ALMT9 from Arabidopsis thaliana (AtALMT9), a malate-activated vacuolar anion channel, in plugged and unplugged lipid-bound states. In all these states, membrane lipids interact with the ion conduction pathway of AtALMT9. We identify two unplugged states presenting two distinct pore width profiles. Combining structural and functional analysis we identified conserved residues involved in ion conduction and in the pore lipid interaction. Molecular dynamics simulations revealed a peculiar anion conduction mechanism in AtALMT9. We propose a voltage-dependent activation mechanism based on the competition between pore lipids and malate at the cytosolic entrance of the channel.
Structural basis for malate-driven, pore lipid-regulated activation of the Arabidopsis vacuolar anion channel ALMT9.,Lee Y, Demes-Causse E, Yoo J, Jang SY, Jung S, Jaslan J, Hwang GS, Yoo J, De Angeli A, Lee S Nat Commun. 2025 Feb 20;16(1):1817. doi: 10.1038/s41467-025-56940-5. PMID:39979303[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hoekenga OA, Maron LG, Pineros MA, Cancado GM, Shaff J, Kobayashi Y, Ryan PR, Dong B, Delhaize E, Sasaki T, Matsumoto H, Yamamoto Y, Koyama H, Kochian LV. AtALMT1, which encodes a malate transporter, is identified as one of several genes critical for aluminum tolerance in Arabidopsis. Proc Natl Acad Sci U S A. 2006 Jun 20;103(25):9738-43. Epub 2006 Jun 1. PMID:16740662 doi:https://dx.doi.org/0602868103
- ↑ Kobayashi Y, Hoekenga OA, Itoh H, Nakashima M, Saito S, Shaff JE, Maron LG, Pineros MA, Kochian LV, Koyama H. Characterization of AtALMT1 expression in aluminum-inducible malate release and its role for rhizotoxic stress tolerance in Arabidopsis. Plant Physiol. 2007 Nov;145(3):843-52. doi: 10.1104/pp.107.102335. Epub 2007 Sep , 20. PMID:17885092 doi:https://dx.doi.org/10.1104/pp.107.102335
- ↑ Liu J, Magalhaes JV, Shaff J, Kochian LV. Aluminum-activated citrate and malate transporters from the MATE and ALMT families function independently to confer Arabidopsis aluminum tolerance. Plant J. 2009 Feb;57(3):389-99. doi: 10.1111/j.1365-313X.2008.03696.x. Epub 2008 , Oct 30. PMID:18826429 doi:https://dx.doi.org/10.1111/j.1365-313X.2008.03696.x
- ↑ Sawaki Y, Iuchi S, Kobayashi Y, Kobayashi Y, Ikka T, Sakurai N, Fujita M, Shinozaki K, Shibata D, Kobayashi M, Koyama H. STOP1 regulates multiple genes that protect arabidopsis from proton and aluminum toxicities. Plant Physiol. 2009 May;150(1):281-94. doi: 10.1104/pp.108.134700. Epub 2009 Mar , 25. PMID:19321711 doi:https://dx.doi.org/10.1104/pp.108.134700
- ↑ Lee Y, Demes-Causse E, Yoo J, Jang SY, Jung S, Jaślan J, Hwang GS, Yoo J, De Angeli A, Lee S. Structural basis for malate-driven, pore lipid-regulated activation of the Arabidopsis vacuolar anion channel ALMT9. Nat Commun. 2025 Feb 20;16(1):1817. PMID:39979303 doi:10.1038/s41467-025-56940-5
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