Identification of polyphosphate recognition sites communicating with actin sites on the skeletal myosin subfragment 1 heavy chain.

Abstract

Using the thrombin-cut [68-30 kilodalton (kDa)] myosin subfragment 1 (S-1) whose heavy chain has been selectively split within the central 50-kDa region, at Lys-560, with concomitant specific alterations of the ATPase and actin binding properties [Chaussepied, P., Mornet, D., Audemard, E., Derancourt, J., & Kassab, R. (1986) Biochemistry 25, 1134-1140; Chaussepied, P., Mornet, D., Barman, T., Travers, F., & Kassab, R. (1986) Biochemistry 25, 1141-1149], we have isolated and renatured the COOH-terminal 30-kDa fragment associated with the alkali light chains by the procedure recently described [Chaussepied, P., Mornet, D., Audemard, E., Kassab, R., Goodearl, J., Levine, B., & Trayer, I. P. (1986) Biochemistry 25, 4540-4547]. The 30-kDa peptide preparation was found to exhibit a crucial feature of the native S-1; namely, it interacts with F-actin in an adenosine 5'-triphosphate (ATP)-dependent manner. Studies by ultracentrifugation, turbidity measurements, and chemical cross-linking experiments showed that the acto-30-kDa peptide complex was dissociated almost completely by the gamma-phosphoryl group containing ligands ATP, 5'-adenylyl imidodiphosphate, and pyrophosphate, to a lesser extent by ADP, and not at all by AMP and inorganic phosphate. The maximal dissociating effect is operating with the thrombic 30-kDa entity, whereas the 22-kDa fragment produced by staphylococcal protease is only slightly dissociated. In contrast, the tryptic 20-kDa fragment binds irreversibly to actin.(ABSTRACT TRUNCATED AT 250 WORDS)