6o7a | pdb_00006o7a
Crystal structure of the LjCASTOR gating ring in the Ca2+-free state
Structural highlights
Function[CASTO_LOTJA] Ion channel with a moderate preference for potassium over sodium and calcium. Involved in perinuclear calcium spiking but not in cytosolic calcium influx. Closed at negative voltages in presence of magnesium. Required for early signal transduction events leading to endosymbiosis. Acts early in a signal transduction chain leading from the perception of Nod factor to the activation of calcium spiking. Also involved in fungal entry into root epidermal cells during the establishment of the arbuscular mycorrhizal symbiosis.[1] [2] Publication Abstract from PubMedA 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 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 (Regulator of Conductance 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. Ca(2+)-regulated Ca(2+) channels with an RCK gating ring control plant symbiotic associations.,Kim S, Zeng W, Bernard S, Liao J, Venkateshwaran M, Ane JM, Jiang Y Nat Commun. 2019 Aug 16;10(1):3703. doi: 10.1038/s41467-019-11698-5. PMID:31420535[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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