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PubMed · 7961961

Mycalolide B, a novel actin depolymerizing agent.

S Saito·S Watabe·H Ozaki·N Fusetani·H Karaki
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Abstract

We investigated the effects of a novel marine toxin, mycalolide B, on actin polymerization and actin-activated myosin Mg(2+)-ATPase activity using purified actin and myosin from rabbit skeletal muscle. The results were compared with cytochalasin D which inhibits actin polymerization by binding to the barbed end of F-actin. By monitoring fluorescent intensity of pyrenyl-actin, mycalolide B did not accelerate actin polymerization but quickly depolymerized F-actin, whereas cytochalasin D accelerated actin nucleation and depolymerized F-actin at slower rate. The kinetics of depolymerization suggest that mycalolide B severs F-actin. The relationship between the concentration of total actin and F-actin at different concentration of mycalolide B suggests that mycalolide B forms 1:1 complex with G-actin. Viscometry and electron microscopic observation further suggest that actin filament was depolymerized by mycalolide B. Unlike cytochalasin D, furthermore, mycalolide B suppressed actin-activated myosin Mg(2+)-ATPase activity. We concluded that mycalolide B severs F-actin and sequesters G-actin and may serve as a novel pharmacological tool for analyzing actin-mediated cell functions.

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ActinsAnimalsBiopolymersKineticsMarine ToxinsMicroscopy, ElectronMuscle, SkeletalOxazolesPoriferaRabbitsJournal ArticleResearch Support, Non-U.S. Gov't

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S Saito, S Watabe, H Ozaki, N Fusetani, H Karaki. 1994-11-25. Mycalolide B, a novel actin depolymerizing agent.. https://pubmed.ncbi.nlm.nih.gov/7961961/

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