7VM8

Crystal structure of the MtDMI1 gating ring

Summary for 7VM8

• Entry DOI: 10.2210/pdb7vm8/pdb
• Descriptor: Ion channel DMI1 (1 entity in total)
• Functional Keywords: dmi, symbiose, plant protein
• Biological source: Medicago truncatula (Barrel medic, Medicago tribuloides)
• Total number of polymer chains: 1
• Total formula weight: 60475.39

Authors

Huang, X.,Zhang, P. (deposition date: 2021-10-08, release date: 2022-08-24, Last modification date: 2023-11-29)

Primary citation

Liu, H.,Lin, J.S.,Luo, Z.,Sun, J.,Huang, X.,Yang, Y.,Xu, J.,Wang, Y.F.,Zhang, P.,Oldroyd, G.E.D.,Xie, F.
Constitutive activation of a nuclear-localized calcium channel complex in Medicago truncatula.
Proc.Natl.Acad.Sci.USA, 119:e2205920119-e2205920119, 2022

PubMed Abstract: Nuclear Ca 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 oscillations. However, the mechanism of Ca signature generation is unknown. Here, we demonstrate spontaneous activation of this channel complex, through gain-of-function mutations in , leading to spontaneous nuclear Ca oscillations and spontaneous nodulation, in a -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 signals, and provide insights into its native mode of induction.

PubMed: 35972963
DOI: 10.1073/pnas.2205920119

Experimental method

X-RAY DIFFRACTION (3.034 Å)