Conformational changes and gating at the selectivity filter of potassium channels

Area of Science:

• Biophysics
• Molecular Biology
• Structural Biology

Background:

• Ion and water transport across cell membranes is vital for life.
• Potassium (K+) channels are integral membrane proteins facilitating selective K+ passage.
• The mechanisms of K+ channel gating (opening/closing) and inactivation are debated.

Purpose of the Study:

• To investigate the conformational changes in K+ channels during gating and inactivation.
• To computationally study the KirBac channel to identify physical gating mechanisms.
• To elucidate the structural basis of C-type inactivation in K+ channels.

Main Methods:

• Extensive computational simulations of the KirBac channel.
• Analysis of channel structure and dynamics.
• Identification of key residues and structural motifs involved in gating.

Main Results:

• Evidence for a physical gate or constriction within the selectivity filter (SF) of K+ channels.
• Identification of a novel selectivity filter structure associated with C-type inactivation.
• Observed alternating left- and right-handed Ramachandran angles in the SF peptide chains.

Conclusions:

• The study supports a physical gate in the K+ channel SF, likely responsible for C-type inactivation.
• A unique SF structure with alternating dihedral angles is identified.
• The findings justify the evolutionary conservation of glycine in the K+ SF due to its bifunctional role.