title: Beta-tubulin genes from the parasitic nematode Haemonchus contortus modulate drug resistance in Caenorhabditis elegans.
abstract: Resistance to antimitotic chemotherapeutics in pathogenic nematodes, fungi and mammalian cells is closely associated with structural changes in cytoskeletal beta-tubulin. We investigated the possibility of using the well-characterised free-living nematode Caenorhabditis elegans as a model for studying the mechanism of resistance against benzimidazole (BZ) drugs in the parasitic nematode Haemonchus contortus. Functional analysis of a conserved beta-tubulin isotype (tub-1) mutation near GTP-binding domain II, which is linked to BZ resistance, was carried out in C. elegans by heterologous expression of: (1) parasite BZ-sensitive alleles; (2) BZ-resistant alleles; and (3) in vitro mutagenised beta-tubulin gene constructs. The injected heterologous gene constructs were not only stably maintained, but also expressed as shown by reverse transcriptase-polymerase chain reaction analysis. The degree of BZ drug susceptibility of the transformants was assayed and quantified by incubation with both benomyl and thiabendazol. All H. contortus tub-1 constructs, which encoded Phe at position 200, conferred susceptibility to thiabendazole in BZ-resistant C. elegans ben-1 mutants. In contrast, constructs carrying Tyr200 did not alter the BZ drug phenotype. From these experiments we conclude that: (1) C. elegans can be used as an expression host, since injected parasite genes were biologically active; and (2) the single Phe to Tyr mutation at position 200 in beta-tubulin isotype 1 is the cause of BZ resistance in H. contortus.
authors.affiliation: Department of Parasitology and Tropical Veterinary Medicine, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
authors.forename: M S
authors.initials: MS
authors.lastname: Kwa
authors.forename: J G
authors.initials: JG
authors.lastname: Veenstra
authors.forename: M
authors.initials: M
authors.lastname: Van Dijk
authors.forename: M H
authors.initials: MH
authors.lastname: Roos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology*; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics; D006189:Haemonchus / Q000187:drug effects* / Q000235:genetics*; D015801:Helminth Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D013329:Structure-Activity Relationship; D014170:Transformation, Genetic; D014404:Tubulin / Q000235:genetics*
chemical_list: D000969:Antinematodal Agents; D015801:Helminth Proteins; D014404:Tubulin