AI-driven mechanistic analysis of conformational dynamics in CNNM/CorC Mg2+ transporters.

The CNNM/CorC Mg2+ transporters are widely conserved in eukaryotes (cyclin M [CNNM]) and prokaryotes (CorC) and participate in various biological processes. Previous structural analyses of the CorC transmembrane domain in the Mg2+-bound inward-facing conformation revealed the conserved Mg2+ recognition mechanism in the CNNM/CorC family; however, the conformational dynamics in the Mg2+ transport cycle remain unclear because structures in other conformations are unknown. Here, we used AlphaFold structure prediction to predict the occluded-like and outward-facing-like conformations of the CorC and CNNM proteins and identified conserved hydrophilic interactions close to the cytoplasmic side in these conformations. Molecular dynamics simulations and biochemical cross-linking showed that these conserved hydrophilic interactions are stable, especially in the outward-facing-like conformation. Furthermore, mutational analysis revealed that the residues involved in these hydrophilic interactions on the cytoplasmic side are important for Mg2+ transport in the CorC and CNNM proteins. Our work provides mechanistic insights into the transport cycle of the CNNM/CorC family. [Display omitted] • AlphaFold predicted the occluded and outward-facing conformations of CNNM and CorC • The conserved hydrophilic interactions close to the cytoplasmic side were predicted • The predicted structures were validated by MD simulations and functional analyses • A transport cycle mechanism for CNNM/CorC Mg2+ transporters was proposed The CNNM/CorC Mg2+ transporters are widely conserved in eukaryotes and prokaryotes and participate in various biological processes. Ma et al. used AlphaFold to predict their occluded-like and outward-facing-like conformations in the absence of known experimental structures. The predicted structures were subsequently validated by MD simulations and functional analyses. [ABSTRACT FROM AUTHOR]