Ataxin-3 consists of an N-terminal globular Josephin domain and an unstructured C-terminal region containing a stretch of consecutive glutamines that triggers an inherited neurodegenerative disorder, spinocerebellar ataxia type 3, when its length exceeds a critical threshold. The pathology results from protein misfolding and intracellular accumulation of fibrillar amyloid-like aggregates. Plenty of work has been carried out to elucidate the protein's physiological role(s), which has shown that ataxin-3 is multifunctional; it acts as a transcriptional repressor, and also has polyubiquitin-binding/ubiquitin-hydrolase activity. In addition, a recent report shows that it participates in sorting misfolded protein to aggresomes, close to the microtubule-organizing center. Since a thorough understanding of the protein's physiological role(s) requires the identification of all the molecular partners interacting with ataxin-3, we pursued this goal by taking advantage of two-dimensional chromatography coupled to tandem mass spectrometry. We found that different ataxin-3 constructs, including the sole Josephin domain, bound alpha- and beta-tubulin from soluble rat brain extracts. Coimmunoprecipitation experiments confirmed this interaction. Also, normal ataxin-3 overexpressed in COS7 cultured cells partially colocalized with microtubules, whereas an expanded variant only occasionally did so, probably due to aggregation. Furthermore, by surface plasmon resonance we determined a dissociation constant of 50-70nM between ataxin-3 and tubulin dimer, which strongly supports the hypothesis of a direct interaction of this protein with microtubules in vivo. These findings suggest an involvement of ataxin-3 in directing aggregated protein to aggresomes, and shed light on the mode of interaction among the different molecular partners participating in the process.
Mazzucchelli, S., De Palma, A., Riva, M., D'Urzo, A., Pozzi, C., Pastori, V., et al. (2009). Proteomic and biochemical analyses unveil tight interaction of ataxin-3 with tubulin. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY & CELL BIOLOGY, 41, 2485-2492.
|Citazione:||Mazzucchelli, S., De Palma, A., Riva, M., D'Urzo, A., Pozzi, C., Pastori, V., et al. (2009). Proteomic and biochemical analyses unveil tight interaction of ataxin-3 with tubulin. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY & CELL BIOLOGY, 41, 2485-2492.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Titolo:||Proteomic and biochemical analyses unveil tight interaction of ataxin-3 with tubulin|
|Autori:||Mazzucchelli, S; De Palma, A; Riva, M; D'Urzo, A; Pozzi, C; Pastori, V; Comelli, F; Fusi, PA; Vanoni, ME; Tortora, P; Mauri, P; Regonesi, ME|
|Data di pubblicazione:||ago-2009|
|Rivista:||THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY & CELL BIOLOGY|
|Appare nelle tipologie:||01 - Articolo su rivista|