Mechanism of activation gating in the full-length KcsA K[superscript +] channel
- UC
Using a constitutively active channel mutant, we solved the structure of full-length KcsA in the open conformation at 3.9 {angstrom}. The structure reveals that the activation gate expands about 20 {angstrom}, exerting a strain on the bulge helices in the C-terminal domain and generating side windows large enough to accommodate hydrated K{sup +} ions. Functional and spectroscopic analysis of the gating transition provides direct insight into the allosteric coupling between the activation gate and the selectivity filter. We show that the movement of the inner gate helix is transmitted to the C-terminus as a straightforward expansion, leading to an upward movement and the insertion of the top third of the bulge helix into the membrane. We suggest that by limiting the extent to which the inner gate can open, the cytoplasmic domain also modulates the level of inactivation occurring at the selectivity filter.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- UNIVERSITYNIH
- OSTI ID:
- 1039456
- Journal Information:
- Proc. Natl. Acad. Sci. USA, Vol. 108, Issue (29) ; 07, 2011; ISSN 1091-6490
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Crystal structure of full-length KcsA in its closed conformation
Rapid constriction of the selectivity filter underlies C-type inactivation in the KcsA potassium channel