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Nikolay Tzvetkov, Peter Breuer

Josephin domain containing proteins from a variety of species are active deubiquitination enzymes

Keywords: Ataxin-3, de-ubiquitination, neurodegenerative diseases, polyglutamine proteins, protein misfolding

The neurodegenerative disease Spinocerebellar Ataxia type 3 (SCA3) is caused by the presence of an extended polyglutamine stretch (polyQ) in the unstructured C-terminus of the human Ataxin-3 (AT3) protein. The structured N-terminal Josephin domain (JD) of AT3 is conserved within a novel family of potential ubiquitin proteases, the JD containing proteins, which are subdivided into two groups termed Ataxins and Josephins. These AT3 orthologs are encoded by the genomes of organisms ranging from Plasmodium falciparum to humans with most species possessing more than one homolog. While Josephins consist of JDs alone, Ataxins contain additional functional domains that may influence their enzymatic activity. Here, we show that the enzymatic activity of human AT3 (hAT3) is not affected by the length of polyQ in its C-terminus, even when it is in the range associated with SCA3. We also show that JDs of all human proteins with homology to AT3, and its homologs from various species possess de-ubiquitination activity. These results establish JD containing proteins as a novel family of active de-ubiquitination enzymes with wide phylogenic distribution.

Biological Chemistry, Walter de Gruyter

Print ISSN: 1431-6730
Volume: 2007
Pages: -

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