Polyunsaturated fatty acids (PUFAs) inhibit pentameric ligand-gated ion channels (pLGICs) but the mechanism of inhibition is not well understood. The PUFA, docosahexaenoic acid (DHA), inhibits agonist responses of the pLGIC, ELIC, more effectively than palmitic acid, similar to the effects observed in the GABAA receptor and nicotinic acetylcholine receptor. Using photo-affinity labeling and coarse-grained molecular dynamics simulations, we identified two fatty acid binding sites in the outer transmembrane domain (TMD) of ELIC. Fatty acid binding to the photolabeled sites is selective for DHA over palmitic acid, and specific for an agonist-bound state. Hexadecyl-methanethiosulfonate modification of one of the two fatty acid binding sites in the outer TMD recapitulates the inhibitory effect of PUFAs in ELIC. The results demonstrate that DHA selectively binds to multiple sites in the outer TMD of ELIC, but that state-dependent binding to a single intrasubunit site mediates DHA inhibition of ELIC.
Figure 4- source data 1 contains the numerical data used to generate Figure 4A and 4B. Figure 4- source data 2 contains the numerical data used to generate Figure 4C and Figure 4- figure supplement 5. Figure 4- source data 3 contains the statistical analysis (linear mixed effects model) for Figure 4- figure supplement 5.
- Wayland WL Cheng
- John T Petroff II
- Douglas F Covey
- Douglas F Covey
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Marcel P Goldschen-Ohm, University of Texas at Austin, United States
© 2022, Dietzen et al.
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