Molecular defects of the dystonia-causing torsinA mutation

The DeltaGAG deletion mutation in DYT1, causing a loss of a glutamic acid near the carboxyl terminus of torsinA protein (torsinADeltaE), is dominantly inherited and tends to result in a severe generalized form of dystonia with childhood onset. We have used a yeast two-hybrid interaction assay to examine torsinA and its mutant torsinADeltaE interactions. Our data showed that torsinA monomers are capable of interacting with themselves and that mutant torsinADeltaE fails to interact with itself or with torsinA. We also demonstrated that purified torsinA protein is an ATPase, which forms a multimeric complex in vitro and that the DeltaGAG mutation disrupts the formation of multimeric complex and decreases torsinA's ATPase activity.