Download MendeleyCalcium stabilizes the flexible N-terminal domain of the bacterial ion channel DeCLIC.
Fan, C., Lycksell, M., Zhuang, Y., Howard, R.J., Lindahl, E.(2025) J Struct Biol X 12: 100139-100139
- PubMed: 41328424
- DOI: https://doi.org/10.1016/j.yjsbx.2025.100139
- Primary Citation of Related Structures:
9EV1, 9EV7, 9EV8, 9EV9, 9EVA, 9EVB - PubMed Abstract:
Pentameric ligand-gated ion channels (pLGICs) are responsible for the rapid conversion of chemical to electrical signals. In addition to the canonical extracellular and transmembrane domains, some prokaryotic pLGICs contain an N-terminal domain (NTD) of unclear structure and function. In one such case, the calcium-sensitive channel DeCLIC, the NTD appears to accelerate gating; however, its evident flexibility has posed a challenge to model building, and its role in calcium sensitivity is unclear. Here we report cryo-EM structures of DeCLIC in circularized lipid nanodiscs, achieving the highest resolution reported so far, and enabling definition of calcium-binding sites in both the N-terminal and canonical extracellular domains. In addition to the symmetric state, calcium depletion promoted an asymmetric conformation of the NTD, offering a structural rationale for small-angle scattering results. Behavior of these structures in molecular dynamics simulations demonstrated calcium stabilization of the NTD. These features of DeCLIC offer a model system for ion-channel modulation by a flexible accessory domain, potentially conserved in structurally homologous systems across evolution.
- Dept. of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden.
Organizational Affiliation:
