Activation mechanism of ATP-sensitive K+ channels explored with real-time nucleotide binding

Journal article

The response of ATP-sensitive K+ channels (KATP) to cellular metabolism is coordinated by three classes of nucleotide binding site (NBS). We used a novel approach involving labeling of intact channels in a native, membrane environment with a non-canonical fluorescent amino acid and measurement (using FRET with fluorescent nucleotides) of steady-state and time-resolved nucleotide binding to dissect the role of NBS2 of the accessory SUR1 subunit of KATP in channel gating. Binding to NBS2 was Mg2+-independent, but Mg2+ was required to trigger a conformational change in SUR1. Mutation of a lysine (K1384A) in NBS2 that coordinates bound nucleotides increased the EC50 for trinitrophenyl-ADP binding to NBS2, but only in the presence of Mg2+, indicating that this mutation disrupts the ligand-induced conformational change. Comparison of nucleotide-binding with ionic currents suggests a model in which each nucleotide binding event to NBS2 of SUR1 is independent and promotes KATP activation by the same amount.

Authors: Puljung, M; Vedovato, N; Usher, S; Ashcroft, F

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: eLife Sciences
• Journal: eLife
• Volume: 8
• Issue: 2019
• Article number: e41103
• Publication date: 2019-02-21
• Acceptance date: 2019-02-14
• DOI: 10.7554/eLife.41103
• EISSN: 2050-084X
• ISSN: 2050-084X
• Pmid: 30789344
• Language: English
• Keywords: FFR