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Publication Abstract from PubMed

Nitrate is one of the major nitrogen sources for most plants. Chloride channel (CLC) proteins mediate the transport and vacuole storage of nitrate in plants, but the structural basis of nitrate transport by plant CLC proteins remains unknown. Here, we solved the cryo-EM structure of ATP-bound Arabidopsis thaliana CLCa (AtCLCa) at 2.8 A resolution. Structural comparison between nitrate-selective AtCLCa and chloride-selective CLC-7 reveals key differences in the central anion-binding site. We observed that the central nitrate is shifted by approximately 1.4 A from chloride, which is likely caused by a weaker interaction between the anion and Pro160; the side chains of aromatic residues around the central binding site are rearranged to accommodate the larger nitrate. Additionally, we identified the ATP-binding pocket of AtCLCa to be located between the cytosolic cystathionine beta-synthase domains and the N-terminus. The N-terminus may mediate the ATP inhibition of AtCLCa by interacting with both ATP and the pore-forming transmembrane helix. Together, our studies provide insights into the nitrate selectivity and ATP regulation of plant CLCs.

Cryo-EM structure of the plant nitrate transporter AtCLCa reveals characteristics of the anion-binding site and the ATP-binding pocket.,He J, Wang M, Li S, Chen L, Zhang K, She J J Biol Chem. 2023 Feb;299(2):102833. doi: 10.1016/j.jbc.2022.102833. Epub 2022 , Dec 26. PMID:36581207^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.