Domain 2 of gelsolin binds directly to tropomyosin

Gelsolin is an actin filament severing protein composed of sis similar stru ctured domains that differ with respect to actin, calcium and polyphospho-i nositide binding. Previous work has established that gelsolin binds tropomy osin [Koepf, E.K. and Burtnick, L.D. (1992) FEES Lett. 309, 56-58]. We have produced various specific gelsolin domains in Escherichia coli in order to establish which of the sis domains binds tropomyosin. Gelsolin domains 1-3 (G1-3), G1-2 and G2 all bind tropomyosin in a pH and calcium insensitive m anner whereas binding of G4-6 to tropomyosin was barely detectable under th e conditions tested. We conclude that gelsolin binds tropomyosin via domain 2 (G2). (C) 2000 Federation of European Biochemical Societies.