Functional dissection of KATP channel structures reveals the importance of a conserved interface.

ATP-sensitive potassium channels (KATP) are inhibited by ATP but activated by Mg-ADP, coupling the intracellular ATP/ADP ratio to the potassium conductance of the plasma membrane. Although there has been progress in determining the structure of KATP, the functional significance of the domain-domain interface in the gating properties of KATP channels remains incompletely understood. In this study, we define the structure of KATP as two modules: KATP core and SUR ABC. Based on this model, we identified two functionally important interfaces between these two modules, namely interface I and interface II. Further structure-guided mutagenesis experiments indicate that destabilizing interface II by deleting ECL3 on the SUR1 subunit impairs KNtp-independent Mg-ADP activation, demonstrating the essential role of intramolecular interactions between KATP core and SUR ABC in Mg-ADP activation. Additionally, interface II is functionally conserved between SUR1 and SUR2, and the hydrophobic residue F351 on ECL3 of SUR1 is crucial for maintaining the stability of this interface. [Display omitted] • Interfaces I and II between KATP core and SUR ABC are important for KATP gating • Destabilizing interface II by deleting ECL3 impairs KNtp-independent Mg-ADP activation • Interface II is functionally conserved between SUR1 and SUR2 • F351 on ECL3 of SUR1 is crucial for the stability of interface II Yang et al. identified two functionally important interfaces between KATP core and SUR ABC in KATP channels. Structure-guided mutagenesis together with electrophysiological measurements demonstrated the essential role of ECL3 on the interface II of SUR during Mg-ADP activation of KATP channels. [ABSTRACT FROM AUTHOR]