Machado–Joseph disease gene products carrying different carboxyl termini

Goto, Jun; Watanabe, Masahiko; Ichikawa, Yaeko; Yee, Su-Bog; Ihara, Noriyo; Endo, Kotaro; Igarashi, Shuichi; Takiyama, Yoshihisa; Gaspar, Cláudia; Maciel, Patrı́cia; Tsuji, Shoji; Rouleau, Guy A.; Kanazawa, Ichiro

doi:10.1016/s0168-0102(97)00056-4

Cited by 73 publications

(75 citation statements)

References 10 publications

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“…Atax3(Q15)-A construct encoding Atax3(Q15) was engineered by modification of the pQE30 Atax3(Q28) vector that had been created previously (24) from a vector encoding the MJD1a gene variant (7,30). EcoN1 sites flanking the polyglutamine-encoding region were introduced using the QuikChange technique sites coupled with a cassette mutagenesis approach allowing for the manipulation of the length of the polyglutamine tract without introducing or substituting amino acids within the protein.…”

Section: Cloning Of Atax3(q15) and Atax3(q50)mentioning

confidence: 99%

Polyglutamine Expansion in Ataxin-3 Does Not Affect Protein Stability

Chow

Ellisdon

Cabrita

et al. 2004

Journal of Biological Chemistry

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Polyglutamine proteins that cause neurodegenerative disease are known to form proteinaceous aggregates, such as nuclear inclusions, in the neurons of affected patients. Although polyglutamine proteins have been shown to form fibrillar aggregates in a variety of contexts, the mechanisms underlying the aberrant conformational changes and aggregation are still not well understood. In this study, we have investigated the hypothesis that polyglutamine expansion in the protein ataxin-3 destabilizes the native protein, leading to the accumulation of a partially unfolded, aggregation-prone intermediate. To examine the relationship between polyglutamine length and native state stability, we produced and analyzed three ataxin-3 variants containing 15, 28, and 50 residues in their respective glutamine tracts. At pH 7.4 and 37°C, Atax3(Q50), which lies within the pathological range, formed fibrils significantly faster than the other proteins. Somewhat surprisingly, we observed no difference in the acid-induced equilibrium and kinetic un/folding transitions of all three proteins, which indicates that the stability of the native conformation was not affected by polyglutamine tract extension. This has led us to reconsider the mechanisms and factors involved in ataxin-3 misfolding, and we have developed a new model for the aggregation process in which the pathways of un/folding and misfolding are distinct and separate. Furthermore, given that native state stability is unaffected by polyglutamine length, we consider the possible role and influence of other factors in the fibrillization of ataxin-3.

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Section: Cloning Of Atax3(q15) and Atax3(q50)mentioning

confidence: 99%

Polyglutamine Expansion in Ataxin-3 Does Not Affect Protein Stability

Chow

Ellisdon

Cabrita

et al. 2004

Journal of Biological Chemistry

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“…Section 1734 solely to indicate this fact. 1 3 The abbreviations used are: poly(Q), polyglutamine; at3, ataxin-3; TEM, transmission electron microscopy; SCA, spinocerebellar ataxia; TBS, Tris-buffered saline; ThT, thioflavin T; SEC, size exclusion chromatography; at3(QHQ), at3 without a poly(Q) tract; at3(Q15), non-pathological length at3 variant with 15 glutamines; at3(Q64), pathological length at3 with 64 glutamines. …”

mentioning

confidence: 99%

The Two-stage Pathway of Ataxin-3 Fibrillogenesis Involves a Polyglutamine-independent Step

Ellisdon¹,

Thomas

Bottomley

2006

Journal of Biological Chemistry

157

196

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The aggregation of ataxin-3 is associated with spinocerebellar ataxia type 3, which is characterized by the formation of intraneuronal aggregates. However, the mechanism of aggregation is currently not well understood. Ataxin-3 consists of a folded Josephin domain followed by two ubiquitin-interacting motifs and a C-terminal polyglutamine tract, which in the non-pathological form is less than 45 residues in length. We demonstrate that ataxin-3 with 64 glutamines (at(Q64)) undergoes a two-stage aggregation. The first stage involves formation of SDS-soluble aggregates, and the second stage results in formation of SDS-insoluble aggregates via the poly(Q) region. Both these first and second stage aggregates display typical amyloid-like characteristics. Under the same conditions at(Q15) and at(QHQ) undergo a single step aggregation event resulting in SDS-soluble aggregates, which does not involve the polyglutamine tract. These aggregates do not convert to the SDSinsoluble form. These observations demonstrate that ataxin-3 has an inherent capacity to aggregate through its non-polyglutamine domains. However, the presence of a pathological length polyglutamine tract introduces an additional step resulting in formation of a highly stable amyloid-like aggregate.Ataxin-3 is a 42-kDa multi-domain protein consisting of an N-terminal Josephin domain, two ubiquitin-interacting motifs, which are situated next to a polymorphous C-terminal polyglutamine (poly(Q)) 3 tract (1, 2). Ataxin-3 functions as a de-ubiquitinating enzyme (3, 4) and binds polyubiquitin chains through the ubiquitin-interacting motifs (5-8). Expansion of the poly(Q) tract beyond 45 residues causes spinocerebellar ataxia type 3 (SCA3) also known as Machado-Joseph disease (9, 10). Similar dynamic expansion of poly(Q) tracts within various other proteins causes a further eight autosomally dominant neurodegenerative diseases, collectively termed poly(Q) diseases (2, 11).Several key observations have led to the conclusion that poly(Q) diseases originate via a toxic gain of function, mediated by poly(Q) tract expansion. Firstly, the manifestation of each poly(Q) disease is directly reliant on a threshold length of consecutive glutamine residues. In all of the diseases, except for SCA6, this threshold is remarkably similar with a tract length in excess of 40 residues associated with disease onset (2).Secondly, there is a non-linear correlation between an increasing glutamine tract length and an earlier age of disease onset (12). Thirdly, different proteins involved in each of the various poly(Q) diseases share no sequence homology except the presence of the glutamine tract (13).Various studies have suggested that this toxic gain of function is causally linked to aberrant protein aggregation mediated by the extended poly(Q) tract (14). In vitro studies have shown that poly(Q) peptides, fragments, and proteins can form amyloid-like fibrillar aggregates and that the aggregation rate increases with increasing glutamine tract length (15)(16)(17)(18)(19). Various types of ...

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“…Ataxin-3 contains an Nterminal Josephin domain (JD), a conserved module named after the Machado-Joseph disease, two ubiquitin (Ub)-interacting motifs (UIMs), a polyQ stretch, and a short variable tail. In one splice variant, the C-terminal region ends with a third putative UIM (3).…”

mentioning

confidence: 99%

Deubiquitinating function of ataxin-3: Insights from the solution structure of the Josephin domain

Mao

Senic-Matuglia

Fiore

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

146

131

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Spinocerebellar ataxia type 3 is a human neurodegenerative disease resulting from polyglutamine tract expansion. The affected protein, ataxin-3, which contains an N-terminal Josephin domain followed by tandem ubiquitin (Ub)-interacting motifs (UIMs) and a polyglutamine stretch, has been implicated in the function of the Ub proteasome system. NMR-based structural analysis has now revealed that the Josephin domain binds Ub and has a papain-like fold that is reminiscent of that of other deubiquitinases, despite primary sequence divergence but consistent with its deubiqutinating activity. Mutation of the catalytic Cys enhances the stability of a complex between ataxin-3 and polyubiquitinated proteins. This effect depends on the integrity of the UIM region, suggesting that the UIMs are bound to the substrate polyubiquitin during catalysis. We propose that ataxin-3 functions as a polyubiquitin chain-editing enzyme.ataxia ͉ polyglutamine ͉ ubiquitin ͉ ubiquitin interaction motif ͉ valosin-containing protein

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Machado–Joseph disease gene products carrying different carboxyl termini

Cited by 73 publications

References 10 publications

Polyglutamine Expansion in Ataxin-3 Does Not Affect Protein Stability

Polyglutamine Expansion in Ataxin-3 Does Not Affect Protein Stability

The Two-stage Pathway of Ataxin-3 Fibrillogenesis Involves a Polyglutamine-independent Step

Deubiquitinating function of ataxin-3: Insights from the solution structure of the Josephin domain

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