Abstract

Expansion of unstable CAG trinucleotide repeats coding for polyglutamine is the cause of at least nine inherited neurodegenerative disorders, that include Huntington’s disease, Machado–Joseph disease and several other spinocerebellar ataxias. Although the disease mechanisms have not yet been fully elucidated, protein misfolding and aggregation seem to be critical steps in disease initiation. Structural information on polyglutamine and on the causative proteins is therefore an essential prerequisite for understanding pathogenesis and designing effective therapeutic strategies. Using a wide range of biophysical techniques, we have investigated the structural properties of proteins carrying polyglutamine stretches, their domain architecture, stability, aggregation properties, and modes of interaction with partners. Our work on a polyglutamine model system and on the protein ataxin-3, that causes Machado–Joseph disease, represents the first structural characterisation of polyglutamine within a protein context and has highlighted the role of flanking domains in modulating aggregation, thereby providing further insights into the mechanisms of neurodegeneration.