EAT-18 is an essential auxiliary protein interacting with the non-alpha nAChR subunit EAT-2 to form a functional receptor
Open Access
- 3 April 2020
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Pathogens
- Vol. 16 (4), e1008396
- https://doi.org/10.1371/journal.ppat.1008396
Abstract
Nematode parasites infect approximately 1.5 billion people globally and are a significant public health concern. There is an accepted need for new, more effective anthelmintic drugs. Nicotinic acetylcholine receptors on parasite nerve and somatic muscle are targets of the cholinomimetic anthelmintics, while glutamate-gated chloride channels in the pharynx of the nematode are affected by the avermectins. Here we describe a novel nicotinic acetylcholine receptor on the nematode pharynx that is a potential new drug target. This homomeric receptor is comprised of five non-α EAT-2 subunits and is not sensitive to existing cholinomimetic anthelmintics. We found that EAT-18, a novel auxiliary subunit protein, is essential for functional expression of the receptor. EAT-18 directly interacts with the mature receptor, and different homologs alter the pharmacological properties. Thus we have described not only a novel potential drug target but also a new type of obligate auxiliary protein for nAChRs. Soil-transmitted helminths affect about a quarter of the worlds’ population. Chemical anthelmintics not only alleviate the threat to human and animal health but also improve agricultural economics and food security. Here we have identified a “druggable” nicotinic acetylcholine receptor (nAChR) subunit, EAT-2, that constitutes the pharyngeal cholinergic receptor in nematodes. The receptor is required for feeding and possibly for reproductive behavior in worms. A selective therapeutic compound targeting this nAChR should either starve the worms or make them sluggish, helping with faster expulsion from the host. The EAT-2 pharyngeal nAChR is a unique receptor formed by five non-α subunits that lack vicinal cysteines in the ligand binding loop-C. To date, all cation selective nAChRs contain at least two α subunits. It is possible that EAT-2 subunits have retained functionality without the vicinal cysteines due to evolutionary modifications and expresses as a new nAChR subtype which doesn’t fit the established dogma based on the study of vertebrate receptors. Our findings also identified a new type of auxiliary protein subunit, which is essential for functional expression of the pharyngeal nAChR and also modulates its pharmacology. To the best of our knowledge, this is the first report of an auxiliary protein that is essential for functional expression in any cys-loop ligand-gated ion channel.Keywords
This publication has 53 references indexed in Scilit:
- A Rapid Western Blotting Protocol for the Xenopus OocyteCold Spring Harbor Protocols, 2013
- Neto1 and Neto2: auxiliary subunits that determine key properties of native kainate receptorsJournal Of Physiology-London, 2012
- Defined criteria for auxiliary subunits of glutamate receptorsJournal Of Physiology-London, 2011
- Eight genes are required for functional reconstitution of the Caenorhabditis elegans levamisole-sensitive acetylcholine receptorProceedings of the National Academy of Sciences of the United States of America, 2008
- RIC‐3: a nicotinic acetylcholine receptor chaperoneBritish Journal of Pharmacology, 2008
- The α-Bungarotoxin-binding Nicotinic Acetylcholine Receptor from Rat Brain Contains Only the α7 SubunitOnline Journal of Public Health Informatics, 1997
- Nicotinic Acetylcholine Receptors in the NematodeCaenorhabditis elegansJournal of Molecular Biology, 1996
- Diversity of neuronal nicotinic acetylcholine receptors: Lessons from behavior and implications for cns therapeuticsLife Sciences, 1995
- Effects of starvation and neuroactive drugs on feeding in Caenorhabditis elegansJournal of Experimental Zoology, 1990
- The structure of the nervous system of the nematodeCaenorhabditis elegansPhilosophical Transactions of the Royal Society of London. B, Biological Sciences, 1986