Abstract
It was shown that substoichiometric concentrations of chaetoglobosin J, one of the fungal metabolites belonging to cytochalasins, inhibited the elongation at the barbed end of an actin filament. Stoichiometric concentrations of chaetoglobosin J decreased both the rate and the extent of actin polymerization in the presence of 75 mM KCI, 0.2 mM ATP and 10 mM Tris-HCI buffer at pH 8.0 and 25°C. In contrast, stoichiometric concentrations of cytochalasin D accelerated actin polymerization. Chaetoglobosin J slowly depolymerized F-actin to G-actin until an equilibrium was reached. Analyses by a number of different methods showed the increase of monomer concentration at equilibrium to depend on chaetoglobosin J concentrations. F-actin under the influence of stoichiometric concentrations of chaetoglobosin J only slightly activated the Mg 2+-enhanced ATPase activity of myosin at low ionic strenght. It is suggested that when the structure of the chaetoglobosin-affected actin filaments is modified, the equilibrium is shifted to the monomer side, and the interaction with myosin is weakened.
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Schedule a callMore From: Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
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