7W6K

Cryo-EM structure of GmALMT12/QUAC1 anion channel

Summary for 7W6K

• Entry DOI: 10.2210/pdb7w6k/pdb
• EMDB information: 32328
• Descriptor: GmALMT12/QUAC1 (1 entity in total)
• Functional Keywords: symmetrical dimer, t-shaped pore, twisted two-layer architecture, malate-modulation, membrane protein
• Biological source: Glycine max (soybean)
• Total number of polymer chains: 2
• Total formula weight: 120643.94

Authors

Qin, L.,Tang, L.H.,Xu, J.S.,Zhang, X.H.,Zhu, Y.,Sun, F.,Su, M.,Zhai, Y.J.,Chen, Y.H. (deposition date: 2021-12-01, release date: 2022-03-16, Last modification date: 2024-06-26)

Primary citation

Qin, L.,Tang, L.H.,Xu, J.S.,Zhang, X.H.,Zhu, Y.,Zhang, C.R.,Wang, M.H.,Liu, X.L.,Li, F.,Sun, F.,Su, M.,Zhai, Y.,Chen, Y.H.
Cryo-EM structure and electrophysiological characterization of ALMT from Glycine max reveal a previously uncharacterized class of anion channels.
Sci Adv, 8:eabm3238-eabm3238, 2022

PubMed Abstract: Aluminum-activated malate transporters (ALMTs) form an anion channel family that plays essential roles in diverse functions in plants. ALMT12, also named QUAC1 (quick anion channel 1), regulates stomatal closure in response to environmental stimuli. However, the molecular basis of ALMT12/QUAC1 activity remains elusive. Here, we describe the cryo-EM structure of ALMT12/QUAC1 from at 3.5-Å resolution. ALMT12/QUAC1 is a symmetrical dimer, forming a single electropositive T-shaped pore across the membrane. The transmembrane and cytoplasmic domains are assembled into a twisted two-layer architecture, with their associated dimeric interfaces nearly perpendicular. ALMT12/QUAC1-mediated currents display rapid kinetics of activation/deactivation and a bell-shaped voltage dependency, reminiscent of the rapid (R)-type anion currents. Our structural and functional analyses reveal a domain-twisting mechanism for malate-mediated activation. Together, our study uncovers the molecular basis for a previously uncharacterized class of anion channels and provides insights into the gating and modulation of the ALMT12/QUAC1 anion channel.

PubMed: 35235352
DOI: 10.1126/sciadv.abm3238

Experimental method

ELECTRON MICROSCOPY (3.5 Å)