Site-directed mutagenesis of Saccharomyces cerevisiae beta-tubulin: interaction between residue 167 and benzimidazole compounds.
Benzimidazoles are widely used as anthelmintic agents and systemic fungicides. In susceptible organisms, benzimidazoles bind to beta-tubulin and block microtubule polymerization. To further characterize this interaction, site-directed mutagenesis followed by gene replacement was used to change Saccharomyces cerevisiae beta-tubulin residue Phe-167 to Tyr. Consistent with previous studies, this mutation resulted in at least 3-4-fold decreased sensitivity to the benzimidazole derivatives carbendazim and nocodazole. The Tyr-167 mutant was cold sensitive, implying a direct effect on benzimidazole binding rather than a nonspecific increase in microtubule stability. Surprisingly, the mutant had 8-fold increased sensitivity to the derivative benomyl, which is structurally identical to carbendazim except at position 1. This suggests that residue 167 interacts with benzimidazoles in the vicinity of the 1-position.
Li
J
J
Department of Microbiology and Immunology, Medical College of Pennsylvania and Hahnemann University, Philadelphia, 19129, USA.
Katiyar
S K
SK
Edlind
T D
TD
D000935:Antifungal Agents / Q000494:pharmacology*; D001542:Benomyl / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology*; D002219:Carbamates; D005800:Genes, Fungal / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D015739:Nocodazole / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D014170:Transformation, Genetic; D014404:Tubulin / Q000737:chemistry* / Q000187:drug effects* / Q000235:genetics
D000935:Antifungal Agents; D001562:Benzimidazoles; D002219:Carbamates; D014404:Tubulin; C006698:carbendazim; D015739:Nocodazole; D001542:Benomyl