Structural Dynamics of the Slide Helix of Inactive/Closed Conformation of KirBac1.1 in Micelles and Membranes: A Fluorescence Approach DOI Creative Commons

Arpan Bysack,

Chandrima Jash,

H. Raghuraman

et al.

The Journal of Membrane Biology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 9, 2025

Inward rectifying potassium (Kir) channels play a critical role in maintaining the resting membrane potential and cellular homeostasis. The high-resolution crystal structure of homotetrameric KirBac1.1 detergent micelles provides snapshot closed state. Similar to micelles, is reported be inactive/closed conformation POPC membranes. slide helix an important structural motif that regulates channel gating. Despite importance lipid-dependent gating, conflicting models have emerged for location its dynamics mimetics poorly understood. Here, we monitored (residues 46–57) both DM membranes utilizing various site-directed fluorescence approaches. We show, using ACMA-based liposome-flux assay, cysteine mutants are not functional, ensuring similar wild-type channel. Time-resolved water accessibility measurements NBD-labeled single-cysteine slide-helix residues suggest at interfacial region might shallower compared micelles. Interestingly, more dynamic physiologically relevant environment, which accompanied by differential hydration throughout helix. Further, REES lifetime distribution analyses significant changes conformational heterogeneity mimetics. Overall, our results give insight into how affect organization state KirBac1.1, highlight lipid–protein interactions

Language: Английский

Structural Dynamics of the Slide Helix of Inactive/Closed Conformation of KirBac1.1 in Micelles and Membranes: A Fluorescence Approach DOI Creative Commons

Arpan Bysack,

Chandrima Jash,

H. Raghuraman

et al.

The Journal of Membrane Biology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 9, 2025

Inward rectifying potassium (Kir) channels play a critical role in maintaining the resting membrane potential and cellular homeostasis. The high-resolution crystal structure of homotetrameric KirBac1.1 detergent micelles provides snapshot closed state. Similar to micelles, is reported be inactive/closed conformation POPC membranes. slide helix an important structural motif that regulates channel gating. Despite importance lipid-dependent gating, conflicting models have emerged for location its dynamics mimetics poorly understood. Here, we monitored (residues 46–57) both DM membranes utilizing various site-directed fluorescence approaches. We show, using ACMA-based liposome-flux assay, cysteine mutants are not functional, ensuring similar wild-type channel. Time-resolved water accessibility measurements NBD-labeled single-cysteine slide-helix residues suggest at interfacial region might shallower compared micelles. Interestingly, more dynamic physiologically relevant environment, which accompanied by differential hydration throughout helix. Further, REES lifetime distribution analyses significant changes conformational heterogeneity mimetics. Overall, our results give insight into how affect organization state KirBac1.1, highlight lipid–protein interactions

Language: Английский

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