Holothurin: an activator of bovine brain 3'-5' phosphodiesterase

The effect of marine toxin, holothurin A, on calmodulin(CaM)-dependent bovine brain 3'-5' phosphodiesterase (PDE) was studied. Holothurin stimulated CaM-depleted PDE in a concentration dependent manner and this interaction was independent of Ca2+ concentrations. Activation of PDE by holothurin was pH and incubation temperature dependent. Heat treatment of holothurin (at 95 degrees C) at various time intervals (2-8 min) decreased its ability to stimulate PDE. CaM-dependent dependent PDE activity was decreased by holothurin. CaM antagonist W-7 and an organochlorine compound chlordecone significantly inhibited holothurin stimulated PDE. These data indicate that holothurin activates CaM-deficient 3'-5' PDE which is antagonized by classical CaM antagonists.