Ca2+-regulated Ca2+ channels with an RCK gating ring control plant symbiotic associations

Sunghoon Kim, Weizhong Zeng, Shane Bernard, Jun Liao, Muthusubramanian Venkateshwaran, Jean Michel Ane, Youxing Jiang

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


A family of plant nuclear ion channels, including DMI1 (Does not Make Infections 1) and its homologs CASTOR and POLLUX, are required for the establishment of legume-microbe symbioses by generating nuclear and perinuclear Ca2+ spiking. Here we show that CASTOR from Lotus japonicus is a highly selective Ca2+ channel whose activation requires cytosolic/nucleosolic Ca2+, 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 (Regulator of Conductance for K+) domains, and four subunits assemble into the gating ring architecture, similar to that of large conductance, Ca2+-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 Ca2+ sites. Our in vitro and in vivo assays also demonstrate the importance of these gating-ring Ca2+ binding sites to the physiological function of CASTOR as well as DMI1.

Original languageEnglish (US)
Article number3703
JournalNature communications
Issue number1
StatePublished - Dec 1 2019

ASJC Scopus subject areas

  • General
  • Physics and Astronomy(all)
  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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