Abstract
Pentameric ligand-gated ion channels undergo subtle conformational cycling to control electrochemical signal transduction in many kingdoms of life. Several crystal structures have now been reported in this family, but the functional relevance of such models remains unclear. Here, we used small-angle neutron scattering (SANS) to probe ambient solution-phase properties of the pH-gated bacterial ion channel GLIC under resting and activating conditions. Data collection was optimized by inline paused-flow size-exclusion chromatography, and exchanging into deuterated detergent to hide the micelle contribution. Resting-state GLIC was the best-fit crystal structure to SANS curves, with no evidence for divergent mechanisms. Moreover, enhanced-sampling molecular-dynamics simulations enabled differential modeling in resting versus activating conditions, with the latter corresponding to an intermediate ensemble of both the extracellular and transmembrane domains. This work demonstrates state-dependent changes in a pentameric ion channel by SANS, an increasingly accessible method for macromolecular characterization with the coming generation of neutron sources.
Highlights
Pentameric ligand-gated ion channels undergo subtle conformational cycling to control electrochemical signal transduction in many kingdoms of life
The proton-gated cation channel GLIC, from the prokaryote Gloeobacter violaceus, has been a popular model system for structure–function studies in this superfamily [3]; it accounts for 40% of all Pentameric ligand-gated ion channels (pLGICs) structures in the Protein Data Bank (PDB)
These values are in line with what is expected from the crystal structures (Rg of 37.9 Afor the closed structure, and 37.4 Afor the open), and from the amino acid sequence of the construct (182.7 kDa)
Summary
Pentameric ligand-gated ion channels undergo subtle conformational cycling to control electrochemical signal transduction in many kingdoms of life. Several prokaryotic pLGICs have been identified, possibly involved in chemotaxis or quorum sensing [2] Despite their physiological significance, our picture of the pLGIC gating landscape is still incomplete, and we only have limited knowledge, e.g., about the structural dynamics of conformations at room temperature or intermediate states, both of which are essential for understanding of fundamental channel biophysics as well as potential drug development. The proton-gated cation channel GLIC, from the prokaryote Gloeobacter violaceus, has been a popular model system for structure–function studies in this superfamily [3]; it accounts for 40% of all pLGIC structures in the Protein Data Bank (PDB) This channel is pH gated, and its structure has been solved at both high and low pH in apparent closed and open states, respectively [4,5,6,7].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
