Na⁺ bridges allosteric activation and osmotic sensing in the BetT transporter for cellular osmotic homeostasis

This dataset comprises structural and cellular imaging data characterizing the Escherichia coli choline transporter BetT. Structural data include cryo-EM structures and corresponding density maps of BetT determined under varied conditions, including different osmotic pressures, pH values, apo states and choline-bound states, as well as multiple truncated constructs. Cellular imaging data consist of phase-contrast microscopy images of E. coli strains: wild-type, BetT knockout, and knockout strains complemented with distinct BetT mutant variants. Images were acquired under three growth conditions: standard M9 medium, M9 medium supplemented with 0.5 M NaCl (hyperosmotic stress), and M9 medium containing 0.5 M NaCl plus choline.