ATP is essential for cellular energy metabolism, but accumulating evidence suggests that it also acts as an extracellular signaling molecule in mammals through two classes of membrane-bound receptors. Plants are known to release ATP in response to wounding, and elevated extracellular ATP triggers responses such as calcium ion release in plant cells. However, homology-based searches have failed to find ATP receptor candidates in plants. Choi et al. now report the identification of the first ATP receptor in Arabidopsis thaliana. A genetic screen of mutagenized Arabidopsis seedlings identified two mutants, referred to as “Does not respond to nucleotides 1” (dorn1-1 and dorn1-2), which lack a cytoplasmic calcium release response in the presence of extracellular ATP. The dorn1 point mutations both mapped to a gene encoding lectin receptor kinase-I.9 (LecRK-I.9), a transmembrane protein with a putative extracellular ligand-binding domain and an intracellular kinase domain. The mutations blocked LecRK-I.9 kinase activity in vitro and in planta, but ATP signaling could be rescued by ectopic expression of wild-type LecRK-I.9. Competition assays using radiolabeled nucleotides and 8-azido-ATP revealed that ATP is the preferred nucleotide ligand of DORN1. Transcriptomic analysis revealed that the ATP-dependent changes in gene expression, which were blocked by dorn1 mutations, overlapped significantly with gene expression changes that occur in response to plant wounding, suggesting that DORN1 may mediate the physiological response to the wounding-induced release of ATP in plants.
About this article
Cite this article
Sheppard, T. Plants pick up ATP. Nat Chem Biol 10, 168 (2014). https://doi.org/10.1038/nchembio.1464