Colchicine binding in the free-living nematode Caenorhabditis elegans.
The [3H]colchicine-binding activity of a crude supernatant of the free-living nematode Caenorhabditis elegans was resolved into a non-saturable component and a tubulin-specific component after partial purification of tubulin by polylysine affinity chromatography. The two fractions displayed opposing thermal dependencies of [3H]colchicine binding, with non-saturable binding increasing, and tubulin binding decreasing, at 4 degrees C. Binding of [3H]colchicine to C.elegans tubulin at 37 degrees C is a pseudo-first-order rate process with a long equilibration time. The affinity of C. elegans tubulin for [3H]colchicine is relatively low (Ka = 1.7 x 10(5) M(-1)) and is characteristic of the colchicine binding affinities observed for tubulins derived from parasitic nematodes. [3H]Colchicine binding to C. elegans tubulin was inhibited by unlabelled colchicine, podophyllotoxin and mebendazole, and was enhanced by vinblastine. The inhibition of [3H]colchicine binding by mebendazole was 10-fold greater for C. elegans tubulin than for ovine brain tubulin. The inhibition of [3H]colchicine binding to C. elegans tubulin by mebendazole is consistent with the recognised anthelmintic action of the benzimidazole carbamates. These data indicate that C. elegans is a useful model for examining the interactions between microtubule inhibitors and the colchicine binding site of nematode tubulin.
Russell
G J
GJ
Department of Veterinary Pathology, University of Sydney, Australia.
Lacey
E
E
D000818:Animals; D001665:Binding Sites; D001921:Brain; D002107:Caenorhabditis / Q000378:metabolism*; D003078:Colchicine / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008463:Mebendazole / Q000494:pharmacology; D011034:Podophyllotoxin / Q000494:pharmacology; D012756:Sheep; D014404:Tubulin / Q000378:metabolism*; D014747:Vinblastine / Q000494:pharmacology
D014404:Tubulin; D014747:Vinblastine; D008463:Mebendazole; D011034:Podophyllotoxin; D003078:Colchicine