title: A DNA-promoted amyloid proteinopathy in Escherichia coli.
abstract: Protein amyloids arise from the conformational conversion and assembly of a soluble protein into fibrilar aggregates with a crossed β-sheet backbone. Amyloid aggregates are able to replicate by acting as a template for the structural transformation and accretion of further protein molecules. In physicochemical terms, amyloids arguably constitute the simplest self-replicative macromolecular assemblies. Similarly to the mammalian proteins PrP and α-synuclein, the winged-helix dimerization (WH1) domain of the bacterial, plasmid-encoded protein RepA can assemble into amyloid fibres upon binding to DNA in vitro. Here we report that a hyper-amyloidogenic functional variant (A31V) of RepA, fused to a red fluorescent protein, causes an amyloid proteinopathy in Escherichia coli with the following features: (i) in the presence of multiple copies of the specific DNA sequence opsp, WH1(A31V) accumulates as cytoplasmatic inclusions segregated from the nucleoid; (ii) such aggregates are amyloid in nature; (iii) bacteria carrying the amyloid inclusions age, exhibiting a fivefold expanded generation time; (iv) before cytokinesis, small inclusions are assembled de novo and transferred to the daughter cells, in which transmission failures cure amyloidosis; and (v) in the absence of inducer DNA, purified cellular WH1(A31V) inclusions seed amyloid fibre growth in vitro from the soluble protein. RepA-WH1 is a suitable bacterial model system for amyloid proteinopathies.
authors.affiliation: Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas - CSIC, C/Ramiro de Maeztu, 9, E-28040 Madrid, Spain.
authors.forename: M Elena
authors.initials: ME
authors.lastname: Fernández-Tresguerres
authors.forename: Susana Moreno-Díaz
authors.initials: SM
authors.lastname: de la Espina
authors.forename: Fátima
authors.initials: F
authors.lastname: Gasset-Rosa
authors.forename: Rafael
authors.initials: R
authors.lastname: Giraldo
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D001483:Base Sequence; D004265:DNA Helicases / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000378:metabolism*; D050939:Gene Fusion; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D000682:Amyloid; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases