Probing Ion Configurations in the KcsA Selectivity Filter with Single-Isotope Labels and 2D IR Spectroscopy.

ABSTRACT: The potassium ion (K⁺) configurations of the selectivity filter of the KcsA ion channel protein are investigated with two-dimensional infrared (2D IR) spectroscopy of amide I vibrations. Single ¹³C-¹⁸O isotope labels are used, for the first time, to selectively probe the S1/S2 or S2/S3 binding sites in the selectivity filter. These binding sites have the largest differences in ion occupancy in two competing K⁺ transport mechanisms: soft-knock and hard-knock. According to the former, water molecules alternate between K⁺ ions in the selectivity filter while the latter assumes that K⁺ ions occupy the adjacent sites. Molecular dynamics simulations and computational spectroscopy are employed to interpret experimental 2D IR spectr

SUBMITTER: Ryan MJ 

PROVIDER: S-EPMC10450685 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature