title: Amyloidogenesis of bacterial prionoid RepA-WH1 recapitulates dimer to monomer transitions of RepA in DNA replication initiation.
abstract: Most available structures of amyloids correspond to peptide fragments that self-assemble in extended cross β sheets. However, structures in which a whole protein domain acts as building block of an amyloid fiber are scarce, in spite of their relevance to understand amyloidogenesis. Here, we use electron microscopy (EM) and atomic force microscopy (AFM) to analyze the structure of amyloid filaments assembled by RepA-WH1, a winged-helix domain from a DNA replication initiator in bacterial plasmids. RepA-WH1 functions as a cytotoxic bacterial prionoid that recapitulates features of mammalian amyloid proteinopathies. RepA are dimers that monomerize at the origin to initiate replication, and we find that RepA-WH1 reproduces this transition to form amyloids. RepA-WH1 assembles double helical filaments by lateral association of a single-stranded precursor built by monomers. Double filaments then associate in mature fibers. The intracellular and cytotoxic RepA-WH1 aggregates might reproduce the hierarchical assembly of human amyloidogenic proteins.
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Torreira
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Moreno-Del Álamo
authors.affiliation: Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Fuentes-Perez
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernández
authors.affiliation: Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Martín-Benito
authors.affiliation: Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Darwin 3, 28049 Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Moreno-Herrero
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain. Electronic address: rgiraldo@cib.csic.es.
authors.forename: Rafael
authors.initials: R
authors.lastname: Giraldo
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain. Electronic address: ollorca@cib.csic.es.
authors.forename: Oscar
authors.initials: O
authors.lastname: Llorca
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D004261:DNA Replication; D019077:Helix-Turn-Helix Motifs; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D008958:Models, Molecular; D011328:Prions / Q000737:chemistry / Q000378:metabolism; D066329:Protein Aggregates; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000682:Amyloid; D011328:Prions; D066329:Protein Aggregates; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases