4QE9

Open MthK pore structure soaked in 10 mM Ba2+/100 mM K+

Summary for 4QE9

• Entry DOI: 10.2210/pdb4qe9/pdb
• Related: 3LDC 3LDD 3LDE 4QE7
• Descriptor: Calcium-gated potassium channel MthK, POTASSIUM ION (3 entities in total)
• Functional Keywords: transmembrane, ion channel, open conformation, transport protein
• Biological source: Methanothermobacter thermautotrophicus
• Cellular location: Cell membrane; Multi-pass membrane protein: O27564
• Total number of polymer chains: 1
• Total formula weight: 9383.27

Authors

Guo, R.,Zeng, W.,Cui, H.,Chen, L.,Ye, S. (deposition date: 2014-05-15, release date: 2014-07-09, Last modification date: 2023-11-08)

Primary citation

Guo, R.,Zeng, W.,Cui, H.,Chen, L.,Ye, S.
Ionic interactions of Ba2+ blockades in the MthK K+ channel
J.Gen.Physiol., 144:193-200, 2014

PubMed Abstract: The movement and interaction of multiple ions passing through in single file underlie various fundamental K(+) channel properties, from the effective conduction of K(+) ions to channel blockade by Ba(2+) ions. In this study, we used single-channel electrophysiology and x-ray crystallography to probe the interactions of Ba(2+) with permeant ions within the ion conduction pathway of the MthK K(+) channel. We found that, as typical of K(+) channels, the MthK channel was blocked by Ba(2+) at the internal side, and the Ba(2+)-blocking effect was enhanced by external K(+). We also obtained crystal structures of the MthK K(+) channel pore in both Ba(2+)-Na(+) and Ba(2+)-K(+) environments. In the Ba(2+)-Na(+) environment, we found that a single Ba(2+) ion remained bound in the selectivity filter, preferably at site 2, whereas in the Ba(2+)-K(+) environment, Ba(2+) ions were predominantly distributed between sites 3 and 4. These ionic configurations are remarkably consistent with the functional studies and identify a molecular basis for Ba(2+) blockade of K(+) channels.

PubMed: 25024268
DOI: 10.1085/jgp.201411192

Experimental method

X-RAY DIFFRACTION (2.15 Å)