3KXD

Crystal structure of the mthk rck in complex with cadmium

Summary for 3KXD

• Entry DOI: 10.2210/pdb3kxd/pdb
• Related: 2AEF 2AEJ
• Descriptor: Calcium-gated potassium channel mthK, CADMIUM ION (3 entities in total)
• Functional Keywords: rck, mthk, cadmium, potassium channel, alternative initiation, ion transport, ionic channel, membrane, metal-binding, potassium, potassium transport, transmembrane, transport, cell membrane, transport protein
• Biological source: Methanothermobacter thermautotrophicus str. Delta H
• Cellular location: Cell membrane; Multi-pass membrane protein: O27564
• Total number of polymer chains: 2
• Total formula weight: 50132.18

Authors

Dvir, H.,Choe, S. (deposition date: 2009-12-02, release date: 2010-04-21, Last modification date: 2023-09-06)

Primary citation

Dvir, H.,Valera, E.,Choe, S.
Structure of the MthK RCK in complex with cadmium.
J.Struct.Biol., 171:231-237, 2010

PubMed Abstract: RCK is a cytoplasmic regulatory domain of calcium-gated potassium channels. Binding of Ca(2+) by RCK leads to channel activation through a series of yet unknown conformational changes. Structures of the K(+) channel, MthK, and its cytoplasmic RCK domain revealed two binding sites for Ca(2+) per dimer. We determined the crystal structure of RCK in complex with Cd(2+) at 2.2A resolution. Cd(2+) activates MthK more efficiently, and binds at the same binding sites for Ca(2+) but with reduced coordination number. Two additional binding sites for Cd(2+) are found per dimer; one on the main Rossman-fold lobe, and the other on the small lobe of RCK. Using patch-clamp experiments, we demonstrate that Cd(2+) binding to these novel sites enhances activation by Cd(2+) and not by Ca(2+). The structure reveals a large negatively charged surface patch in the proximity of the Ca(2+)/Cd(2+) binding sites, charge neutralization of which appears to promote the channel open state.

PubMed: 20371380
DOI: 10.1016/j.jsb.2010.03.020

Experimental method

X-RAY DIFFRACTION (2.2 Å)