4EI2

Crystal Structures of MthK RCK gating ring bound to Barium

Summary for 4EI2

• Entry DOI: 10.2210/pdb4ei2/pdb
• Related: 2FY8 3RBZ
• Descriptor: Calcium-gated potassium channel mthK, BARIUM ION (3 entities in total)
• Functional Keywords: k+ channel, membrane protein, rck domain, ba2+ binding, rossmann-fold, transport protein
• Biological source: Methanothermobacter thermautotrophicus
• Cellular location: Cell membrane; Multi-pass membrane protein: O27564
• Total number of polymer chains: 16
• Total formula weight: 438029.14

Authors

Smith, F.J.,Cingolani, G.,Rothberg, B.S. (deposition date: 2012-04-04, release date: 2012-12-19, Last modification date: 2024-02-28)

Primary citation

Smith, F.J.,Pau, V.P.,Cingolani, G.,Rothberg, B.S.
Crystal Structure of a Ba(2+)-Bound Gating Ring Reveals Elementary Steps in RCK Domain Activation.
Structure, 20:2038-2047, 2012

PubMed Abstract: RCK domains control activity of a variety of K(+) channels and transporters through binding of cytoplasmic ligands. To gain insight toward mechanisms of RCK domain activation, we solved the structure of the RCK domain from the Ca(2+)-gated K(+) channel, MthK, bound with Ba(2+), at 3.1 Å resolution. The Ba(2+)-bound RCK domain was assembled as an octameric gating ring, as observed in structures of the full-length MthK channel, and shows Ba(2+) bound at several positions. One of the Ba(2+) sites, termed C1, overlaps with a known Ca(2+)-activation site, determined by residues D184 and E210. Functionally, Ba(2+) can activate reconstituted MthK channels as observed in electrophysiological recordings, whereas Mg(2+) (up to 100 mM) was ineffective. Ba(2+) activation was abolished by the mutation D184N, suggesting that Ba(2+) activates primarily through the C1 site. Our results suggest a working hypothesis for a sequence of ligand-dependent conformational changes that may underlie RCK domain activation and channel gating.

PubMed: 23085076
DOI: 10.1016/j.str.2012.09.014

Experimental method

X-RAY DIFFRACTION (3.108 Å)