title: How Epigallocatechin-3-gallate and Tetracycline Interact with the Josephin Domain of Ataxin-3 and Alter Its Aggregation Mode.
abstract: Epigallocatechin-3-gallate (EGCG) and tetracycline are two known inhibitors of amyloid aggregation able to counteract the fibrillation of most of the proteins involved in neurodegenerative diseases. We have recently investigated their effect on ataxin-3 (AT3), the polyglutamine-containing protein responsible for spinocerebellar ataxia type 3. We previously showed that EGCG and tetracycline can contrast the aggregation process and toxicity of expanded AT3, although by different mechanisms. Here, we have performed further experiments by using the sole Josephin domain (JD) to further elucidate the mechanism of action of the two compounds. By protein solubility assays and FTIR spectroscopy we have first observed that EGCG and tetracycline affect the JD aggregation essentially in the same way displayed when acting on the full-length expanded AT3. Then, by saturation transfer difference (STD) NMR experiments, we have shown that EGCG binds both the monomeric and the oligomeric JD form, whereas tetracycline can only interact with the oligomeric one. Surface plasmon resonance (SPR) analysis has confirmed the capability of the sole EGCG to bind monomeric JD, although with a KD value suggestive for a non-specific interaction. Our investigations provide new details on the JD interaction with EGCG and tetracycline, which could explain the different mechanisms by which the two compounds reduce the toxicity of AT3.
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).
authors.forename: Marcella
authors.initials: M
authors.lastname: Bonanomi
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).
authors.forename: Cristina
authors.initials: C
authors.lastname: Visentin
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).|Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM), UdR Milano-Bicocca, Milano (Italy).|Milan Center of Neuroscience (NeuroMI), 20126 Milano (Italy).
authors.forename: Antonino
authors.initials: A
authors.lastname: Natalello
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).|SysBio Centre for Systems Biology, Milano and Rome (Italy).
authors.forename: Michela
authors.initials: M
authors.lastname: Spinelli
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).|Milan Center of Neuroscience (NeuroMI), 20126 Milano (Italy).|SysBio Centre for Systems Biology, Milano and Rome (Italy).
authors.forename: Marco
authors.initials: M
authors.lastname: Vanoni
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy). cristina.airoldi@unimib.it.|Milan Center of Neuroscience (NeuroMI), 20126 Milano (Italy). cristina.airoldi@unimib.it.|SysBio Centre for Systems Biology, Milano and Rome (Italy). cristina.airoldi@unimib.it.
authors.forename: Cristina
authors.initials: C
authors.lastname: Airoldi
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy). mariaelena.regonesi@unimib.it.|Milan Center of Neuroscience (NeuroMI), 20126 Milano (Italy). mariaelena.regonesi@unimib.it.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Regonesi
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano (Italy).|Milan Center of Neuroscience (NeuroMI), 20126 Milano (Italy).
authors.forename: Paolo
authors.initials: P
authors.lastname: Tortora
mesh_terms: D000682:Amyloid / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D000067699:Ataxin-3 / Q000737:chemistry* / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000737:chemistry* / Q000494:pharmacology*; D010455:Peptides; D012097:Repressor Proteins / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013752:Tetracycline / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000682:Amyloid; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D010455:Peptides; D012097:Repressor Proteins; C097188:polyglutamine; D002392:Catechin; C045651:epigallocatechin gallate; D000067699:Ataxin-3; D013752:Tetracycline
keywords: Josephin domain; aggregation inhibitors; epigallocatechin-3-gallate; molecular recognition; tetracyclines