Abstract:
:KcsA is a prokaryotic pH-dependent potassium (K) channel. Its activation, by a decrease in the intracellular pH, is coupled with its subsequent inactivation, but the underlying mechanisms remain elusive. Here, we have investigated the conformational changes and equilibrium of KcsA by using solution NMR spectroscopy. Controlling the temperature and pH of KcsA samples produced three distinct methyl-TROSY and NOESY spectra, corresponding to the resting, activated, and inactivated states. The pH-dependence of the signals from the extracellular side was affected by the mutation of H25 on the intracellular side, indicating the coupled conformational changes of the extracellular and intracellular gates. K(+) titration and NOE experiments revealed that the inactivated state was obtained by the replacement of K(+) with H(2)O, which may interfere with the K(+)-permeation. This structural basis of the activation-coupled inactivation is closely related to the C-type inactivation of other K channels.
journal_name
Proc Natl Acad Sci U S Aauthors
Imai S,Osawa M,Takeuchi K,Shimada Idoi
10.1073/pnas.0911270107subject
Has Abstractpub_date
2010-04-06 00:00:00pages
6216-21issue
14eissn
0027-8424issn
1091-6490pii
0911270107journal_volume
107pub_type
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