title: Binding of sulphonated indigo derivatives to RepA-WH1 inhibits DNA-induced protein amyloidogenesis.
abstract: The quest for inducers and inhibitors of protein amyloidogenesis is of utmost interest, since they are key tools to understand the molecular bases of proteinopathies such as Alzheimer, Parkinson, Huntington and Creutzfeldt-Jakob diseases. It is also expected that such molecules could lead to valid therapeutic agents. In common with the mammalian prion protein (PrP), the N-terminal Winged-Helix (WH1) domain of the pPS10 plasmid replication protein (RepA) assembles in vitro into a variety of amyloid nanostructures upon binding to different specific dsDNA sequences. Here we show that di- (S2) and tetra-sulphonated (S4) derivatives of indigo stain dock at the DNA recognition interface in the RepA-WH1 dimer. They compete binding of RepA to its natural target dsDNA repeats, found at the repA operator and at the origin of replication of the plasmid. Calorimetry points to the existence of a major site, with micromolar affinity, for S4-indigo in RepA-WH1 dimers. As revealed by electron microscopy, in the presence of inducer dsDNA, both S2/S4 stains inhibit the assembly of RepA-WH1 into fibres. These results validate the concept that DNA can promote protein assembly into amyloids and reveal that the binding sites of effector molecules can be targeted to inhibit amyloidogenesis.
authors.affiliation: Department of Molecular Microbiology, Centro de Investigaciones Biológicas (CSIC), C/ Ramiro de Maeztu, 9. E-28040 Madrid, Spain.
authors.forename: Fátima
authors.initials: F
authors.lastname: Gasset-Rosa
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Maté
authors.forename: Cristina
authors.initials: C
authors.lastname: Dávila-Fajardo
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Bravo
authors.forename: Rafael
authors.initials: R
authors.lastname: Giraldo
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000648:ultrastructure; D001665:Binding Sites; D001667:Binding, Competitive; D004247:DNA / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D007203:Indigo Carmine / Q000737:chemistry* / Q000494:pharmacology*; D007211:Indoles / Q000737:chemistry* / Q000494:pharmacology*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D013816:Thermodynamics; D015534:Trans-Activators / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism
chemical_list: D000682:Amyloid; D004268:DNA-Binding Proteins; D007211:Indoles; D015534:Trans-Activators; C045264:replication initiator protein; C032546:indigotetrasulfonic acid; D004247:DNA; D007203:Indigo Carmine; D004265:DNA Helicases