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DNAJB6 is a peptide-binding chaperone which can suppress amyloid fibrillation of polyglutamine peptides at substoichiometric molar ratios

Mansson, C., Kakkar, V., Monsellier, E., Sourigues, Y., Harmark, J., Kampinga, H. H., Melki, R. & Emanuelsson, C., Mar-2014, In : Cell stress & chaperones. 19, 2, p. 227-239 13 p.

Research output: Contribution to journalArticleAcademicpeer-review

  • Cecilia Mansson
  • Vaishali Kakkar
  • Elodie Monsellier
  • Yannick Sourigues
  • Johan Harmark
  • Harm H. Kampinga
  • Ronald Melki
  • Cecilia Emanuelsson

Expanded polyglutamine (polyQ) stretches lead to protein aggregation and severe neurodegenerative diseases. A highly efficient suppressor of polyQ aggregation was identified, the DNAJB6, when molecular chaperones from the HSPH, HSPA, and DNAJ families were screened for huntingtin exon 1 aggregation in cells (Hageman et al. in Mol Cell 37(3):355-369, 2010). Furthermore, also aggregation of polyQ peptides expressed in cells was recently found to be efficiently suppressed by co-expression of DNAJB6 (Gillis et al. in J Biol Chem 288:17225-17237, 2013). These suppression effects can be due to an indirect effect of DNAJB6 on other cellular components or to a direct interaction between DNAJB6 and polyQ peptides that may depend on other cellular components. Here, we have purified the DNAJB6 protein to investigate the suppression mechanism. The purified DNAJB6 protein formed large heterogeneous oligomers, in contrast to the more canonical family member DNAJB1 which is dimeric. Purified DNAJB6 protein, at substoichiometric molar ratios, efficiently suppressed fibrillation of polyQ peptides with 45°Q in a thioflavin T fibrillation. No suppression was obtained with DNAJB1, but with the closest homologue to DNAJB6, DNAJB8. The suppression effect was independent of HSPA1 and ATP. These data, based on purified proteins and controlled fibrillation in vitro, strongly suggest that the fibrillation suppression is due to a direct protein-protein interaction between the polyQ peptides and DNAJB6 and that the DNAJB6 has unique fibrillation suppression properties lacking in DNAJB1. Together, the data obtained in cells and in vitro support the view that DNAJB6 is a peptide-binding chaperone that can interact with polyQ peptides that are incompletely degraded by and released from the proteasome.

Original languageEnglish
Pages (from-to)227-239
Number of pages13
JournalCell stress & chaperones
Volume19
Issue number2
Publication statusPublished - Mar-2014

    Keywords

  • Aggregation, Amyloid, DNAJ, Molecular chaperones, Polyglutamine, PROTEIN AGGREGATION, MUTANT HUNTINGTIN, NEURODEGENERATIVE DISEASE, THIOFLAVIN-T, TOXICITY, DROSOPHILA, EXPANSION, CLEAVAGE, HSP70, SIZE

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