This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Flavin, M. Articles by Slaughter, C. Search for Related Content PubMed PubMed Citation Articles by Flavin, M. Articles by Slaughter, C.

Microtubule Assembly and Function in Chlamydomonas: Inhibition of Growth and Flagellar Regeneration by Antitubulins and Other Drugs and Isolation of Resistant Mutants

¹ Laboratory of Biochemistry, National Heart and Lung Institute, National Institutes of Health, Bethesda, Maryland 20014

ABSTRACT

The distribution of microtubules in Chlamydomonas reinhardtii suggests that they are involved in mitosis, cell and nuclear cleavage, and generation of flagella. Vinblastine, colchicine, and podophyllotoxin bind to the protein building block of microtubules (tubulin) and prevent normal assembly. Mutants resistant to these "antitubulin" drugs are candidates to have alterations in tubulin primary structure. We report the ability to inhibit growth, and flagellar regeneration after amputation, of: vinblastine, several colchicine derivatives, two water-soluble derivatives of podophyllotoxin (succinylpodophyllotoxin and epipodophyllotoxin thiuronium bromide), and other substances which may interfere with flagellar assembly or motility (isopropyl N-phenyl carbamate, 2-methoxy-5-nitrotropone, chloral hydrate, caffeine, and nickel acetate). The ability of each drug to inhibit binding of labeled colchicine or podophyllotoxin to mammalian brain tubulin was also determined. The results suggest that only in the cases of colchicine, colcemide, and epipodophyllotoxin thiruonium bromide was the toxicity to Chlamydomonas mediated by inhibition of tubulin assembly. The requirement for high concentrations of colchicine may be due to permeability barriers, since colchicine toxicity was potentiated by deoxycholate. Mutants resistant to antitubulins were isolated after treatment with methyl methanesulfonate. The results with vinblastine were equivocal. Of three mutants resistant to inhibition of growth and flagellar regeneration by colchicine, one was also cross-resistant to epipodophyllotoxin thiuronium bromide.