Download MendeleypH-dependent activation of the Na + /H + antiporter NhaA and conformational dynamics of its N-terminus.
Weng, T.H., Fabian, B., Olkhova, E., Welsch, S., Schmidt, S.L., Danieli, T., Keren, Y., Rimon, A., Safarian, S., Hummer, G., Padan, E., Michel, H.(2026) Nat Commun
- PubMed: 42285937 Search on PubMed
- DOI: https://doi.org/10.1038/s41467-026-73424-2
- Primary Citation Related Structures:
9RH1, 9RH2, 9RH3, 9RH4, 9RH5, 9RH6, 9RH7, 9RH8, 9RH9, 9RHA, 9RHB, 9RHC, 9RHD, 9RHE, 9RHF - PubMed Abstract:
Na⁺/H⁺ antiporters are vital for regulating intracellular pH and sodium ion levels across all domains of life. In Escherichia coli, NhaA is the principal Na⁺/H⁺ antiporter, exhibiting strong pH sensitivity and rapid turnover, yet the structural transitions underlying its activation and substrate recognition have remained obscure. Here, we use single-particle cryo-electron microscopy to determine the conformational ensemble of NhaA across a physiological pH range and in the presence of Na⁺, complemented by constant-pH molecular dynamics simulations. High-resolution structures of apo and Na⁺-bound NhaA reconstituted in lipid nanodiscs reveal progressive opening of the cytoplasmic funnel with increasing pH. We also visualize the previously unresolved N-terminal tail, which forms a dynamic plug at the cytoplasmic entrance under low-pH conditions and disengages at alkaline pH, coinciding with activation. The Na⁺-bound structure captures Na⁺ coordination at the ion-binding site, and simulations suggest potential roles for the conserved charged residues. Together, these findings illuminate how pH sensing, N-terminal gating, and substrate binding are structurally coordinated in NhaA, providing a framework for understanding Na⁺/H⁺ antiporter activation and regulation, and the basis for targeting clinical important antiporters.
- Emeritus Group Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany.
Organizational Affiliation:
