Unraveling the mechanisms of benzimidazole resistance in hookworms: A molecular docking and dynamics study.

BACKGROUND

Benzimidazole resistance is an emerging challenge among parasitic helminths. It is caused by single nucleotide polymorphisms (SNPs) in specific loci in helminths' β-tubulin genes. Field studies and laboratory investigations reported resistance-associated SNPs in 4 codon locations with 7 allelic variations among hookworms. This study aimed to determine the effects of these mutations on the binding efficiency and behavior of the β-tubulin protein in four hookworm species against four benzimidazole drugs.

METHODS

β-tubulin gene coding sequences of Ancylostoma caninum, A. duodenale, A. ceylanicum, and Necator americanus were retrieved, assessed phylogenetically, and used to construct the 3D structure models of the proteins. The modeled protein structures were verified and edited to contain the reported SNPs: Q134H, F167Y, E198A, E198K, E198V, F200L, and F200Y. Benzimidazole drugs such as albendazole (ABZ), fenbendazole (FBZ), mebendazole (MBZ) and oxfendazole (OBZ) were used as ligands. Molecular docking experiments were performed with the wild-type and mutated proteins. Molecular dynamics simulation assessed the dynamic behavior of the β-tubulin-benzimidazole complex.

RESULTS

In silico docking assessments showed that various amino acid substitutions due to resistance-associated SNPs cause alterations in binding affinities and positions. E198K and Q134H in hookworm β-tubulins substantially weakened the binding affinities and altered the binding positions of benzimidazole drugs. Molecular dynamics analysis revealed that these mutations also caused marked reductions in the binding free energies owing to diminished hydrogen bond contacts with the benzimidazole ligands.

CONCLUSION

The evidence shown herein indicates that mutations at positions 198 and 134 are detrimental to conferring benzimidazole resistance among hookworms. The presence of these mutations may alter the efficacy of pharmacological interventions. Hence, further studies should be conducted to assess their emergence among hookworms in endemic areas with histories of chemotherapy.