Structure, function, and ion-binding properties of a K+channel stabilized in the 2,4-ion-bound configuration.Tilegenova, C., Cortes, D.M., Jahovic, N., Hardy, E., Hariharan, P., Guan, L., Cuello, L.G.
(2019) Proc Natl Acad Sci U S A 116: 16829-16834
- PubMed: 31387976
- DOI: https://doi.org/10.1073/pnas.1901888116
- Primary Citation of Related Structures:
6NFU, 6NFV, 6PA0
- PubMed Abstract:
Here, we present the atomic resolution crystallographic structure, the function, and the ion-binding properties of the KcsA mutants, G77A and G77C, that stabilize the 2,4-ion-bound configuration (i.e., water, K + , water, K + -ion-bound configuration) of the K + channel's selectivity filter. A full functional and thermodynamic characterization of the G77A mutant revealed wild-type-like ion selectivity and apparent K + -binding affinity, in addition to showing a lack of C-type inactivation gating and a marked reduction in its single-channel conductance. These structures validate, from a structural point of view, the notion that 2 isoenergetic ion-bound configurations coexist within a K + channel's selectivity filter, which fully agrees with the water-K + -ion-coupled transport detected by streaming potential measurements.
Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430.