Open AccessCa2+-regulated Ca2+ channels with an RCK gating ring control plant symbiotic associations
Author(s) -
Sung Hoon Kim,
Weizhong Zeng,
Shane Bernard,
Jun Liao,
Muthusubramanian Venkateshwaran,
J Ane,
Youxing Jiang
Publication year - 2019
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/s41467-019-11698-5
Subject(s) - gating , lotus japonicus , cytosol , protein subunit , biophysics , ion channel , biology , chemistry , stereochemistry , biochemistry , gene , receptor , mutant , enzyme
A family of plant nuclear ion channels, including DMI1 ( D oes not M ake I nfections 1 ) and its homologs CASTOR and POLLUX, are required for the establishment of legume-microbe symbioses by generating nuclear and perinuclear Ca 2+ spiking. Here we show that CASTOR from Lotus japonicus is a highly selective Ca 2+ channel whose activation requires cytosolic/nucleosolic Ca 2+ , contrary to the previous suggestion of it being a K + channel. Structurally, the cytosolic/nucleosolic ligand-binding soluble region of CASTOR contains two tandem RCK ( R egulator of C onductance for K + ) domains, and four subunits assemble into the gating ring architecture, similar to that of large conductance, Ca 2+ -gated K + (BK) channels despite the lack of sequence similarity. Multiple ion binding sites are clustered at two locations within each subunit, and three of them are identified to be Ca 2+ sites. Our in vitro and in vivo assays also demonstrate the importance of these gating-ring Ca 2+ binding sites to the physiological function of CASTOR as well as DMI1.