Phosphorylation of vimentin head domain inhibits interaction with the carboxyl-terminal end of alpha-helical rod domain studied by surface plasmon resonance measurements

The amino-terminal head domain of vimentin is the target site for several p rotein kinases and phosphorylation induces disassembly of the vimentin inte rmediate filaments in vivo and in vitro. To better understand molecular mec hanisms involved in phosphorylation-dependent disassembly, we examined doma in interactions involving the head domain and the effect of phosphorylation on the interaction, using surface plasmon resonance. We observed that the head domain binds to the carboxyl-terminal helix 2B in the rod domain, unde r physiological ionic strength. This interaction,vas interfered with by A-k inase phosphorylation of the head domain. Deletion of the carboxyl-terminal 20 amino acids of helix 2B resulted in loss of the interaction. Furthermor e, peptide representing the carboxyl-terminal 20 residues of helix 2B had a substantial affinity,vith the head domain but not with the phosphorylated one, These findings support the idea that the interaction between the head domain and the last 20 residues of helix 2B is essential for association of vimentin tetramers into the intermediate filaments and that the phosphoryl ation-dependent disassembly is the result of loss of the interaction. (C) 2 001 Federation of European Biochemical Societies. Published by Elsevier Sci ence B.V. All rights reserved.