7vm8
From Proteopedia
Crystal structure of the MtDMI1 gating ring
Structural highlights
FunctionDMI1_MEDTR 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 mycorrhizal symbiosis. May be involved in the regulation of the calcium channel responsible for calcium spiking by mobilizing another cation, and thereby altering the membrane potential.[1] Publication Abstract from PubMedNuclear Ca(2+) oscillations allow symbiosis signaling, facilitating plant recognition of beneficial microsymbionts, nitrogen-fixing rhizobia, and nutrient-capturing arbuscular mycorrhizal fungi. Two classes of channels, DMI1 and CNGC15, in a complex on the nuclear membrane, coordinate symbiotic Ca(2+) oscillations. However, the mechanism of Ca(2+) signature generation is unknown. Here, we demonstrate spontaneous activation of this channel complex, through gain-of-function mutations in DMI1, leading to spontaneous nuclear Ca(2+) oscillations and spontaneous nodulation, in a CNGC15-dependent manner. The mutations destabilize a hydrogen-bond or salt-bridge network between two RCK domains, with the resultant structural changes, alongside DMI1 cation permeability, activating the channel complex. This channel complex was reconstituted in human HEK293T cell lines, with the resultant calcium influx enhanced by autoactivated DMI1 and CNGC15s. Our results demonstrate the mode of activation of this nuclear channel complex, show that DMI1 and CNGC15 are sufficient to create oscillatory Ca(2+) signals, and provide insights into its native mode of induction. Constitutive activation of a nuclear-localized calcium channel complex in Medicago truncatula.,Liu H, Lin JS, Luo Z, Sun J, Huang X, Yang Y, Xu J, Wang YF, Zhang P, Oldroyd GED, Xie F Proc Natl Acad Sci U S A. 2022 Aug 23;119(34):e2205920119. doi:, 10.1073/pnas.2205920119. Epub 2022 Aug 16. PMID:35972963[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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