Evaluating beta-tubulin variants as predictors of benzimidazole resistance across Caenorhabditis nematodes
Data, analysis scripts, and results from the article "Evaluating beta-tubulin variants as predictors of benzimidazole resistance across Caenorhabditis nematodes"
Benzimidazoles, a widely used class of anthelmintic drugs, target beta-tubulin, disrupt microtubule formation, and delay nematode development. In parasitic nematodes, mutations in beta-tubulin genes are predicted to inhibit benzimidazole binding and are associated with resistance. In the free-living nematode Caenorhabditis elegans, loss-of-function mutations in the beta-tubulin gene ben-1 cause benzimidazole resistance. Although several beta-tubulin mutations serve as established markers of resistance, the prediction of the effects of novel variants in different nematode species remains challenging. Here, we identified novel beta-tubulin variants predicted to confer benzimidazole resistance across wild strains in three Caenorhabditis species: C. elegans, Caenorhabditis briggsae, and Caenorhabditis tropicalis. The three Caenorhabditis species are experimentally tractable, have characterized beta-tubulin gene complements, and defined natural niches, which allowed us to identify variants in beta-tubulin genes and test which variants are associated with resistance. We hypothesized that, if these species experienced similar selective pressures, they would evolve resistance to benzimidazoles by mutations in a beta-tubulin gene (tbb-1, tbb-2, mec-7, tbb-4, and ben-1). In the three Caenorhabditis species, we tested all strains harboring variants in the five conserved beta-tubulin genes for benzimidazole resistance. In C. elegans, we found that a heterogeneous set of variants in ben-1 were associated with resistance. By contrast, only two variants in C. briggsae ben-1 (W21stop and Q134H) were associated with resistance. C. tropicalis was distinct from the other two species, where no strains with variants in any beta-tubulin gene were resistant. We generated deletions of ben-1 in C. briggsae and C. tropicalis and confirmed that loss of ben-1 confers resistance in both species. Our findings reveal species-specific patterns of beta-tubulin-mediated benzimidazole resistance and emphasize that prediction of variants in beta-tubulin genes alone is not sufficient to predict resistance, especially across diverse nematode species.