Structure of the MthK RCK in complex with cadmium.

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

SUBMITTER: Dvir H 

PROVIDER: S-EPMC2956275 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature