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.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.str.2014.11.007 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Addressing Intracellular Amyloidosis in Bacteria with RepA-WH1, a Prion-Like Protein.
Methods Mol Biol
July 2019
Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
Bacteria are the simplest cellular model in which amyloidosis has been addressed. It is well documented that bacterial consortia (biofilms) assemble their extracellular matrix on an amyloid scaffold, yet very few intracellular amyloids are known in bacteria. Here, we describe the methods we have resorted to characterize in Escherichia coli cells the amyloidogenesis, propagation, and dynamics of the RepA-WH1 prionoid.
View Article and Find Full Text PDFOutlining Core Pathways of Amyloid Toxicity in Bacteria with the RepA-WH1 Prionoid.
Front Microbiol
April 2017
Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones CientíficasMadrid, Spain.
The synthetic bacterial prionoid RepA-WH1 causes a vertically transmissible amyloid proteinopathy in that inhibits growth and eventually kills the cells. Recent studies show that RepA-WH1 builds pores through model lipid membranes, suggesting a possible mechanism for bacterial cell death. By comparing acutely (A31V) and mildly (ΔN37) cytotoxic mutant variants of the protein, we report here that RepA-WH1(A31V) expression decreases the intracellular osmotic pressure and compromise bacterial viability under either aerobic or anaerobic conditions.
View Article and Find Full Text PDFNucleation of Amyloid Oligomers by RepA-WH1-Prionoid-Functionalized Gold Nanorods.
Angew Chem Int Ed Engl
September 2016
Departamento de Química Física I, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid, Spain.
Understanding protein amyloidogenesis is an important topic in protein science, fueled by the role of amyloid aggregates, especially oligomers, in the etiology of a number of devastating human degenerative diseases. However, the mechanisms that determine the formation of amyloid oligomers remain elusive due to the high complexity of the amyloidogenesis process. For instance, gold nanoparticles promote or inhibit amyloid fibrillation.
View Article and Find Full Text PDFRepA-WH1 prionoid: Clues from bacteria on factors governing phase transitions in amyloidogenesis.
Prion
January 2017
a Department of Cellular & Molecular Biology , Centro de Investigaciones Biológicas - CSIC , Madrid , Spain.
In bacterial plasmids, Rep proteins initiate DNA replication by undergoing a structural transformation coupled to dimer dissociation. Amyloidogenesis of the 'winged-helix' N-terminal domain of RepA (WH1) is triggered in vitro upon binding to plasmid-specific DNA sequences, and occurs at the bacterial nucleoid in vivo. Amyloid fibers are made of distorted RepA-WH1 monomers that assemble as single or double intertwined tubular protofilaments.
View Article and Find Full Text PDFPre-amyloid oligomers of the proteotoxic RepA-WH1 prionoid assemble at the bacterial nucleoid.
Sci Rep
October 2015
Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas - CSIC, Madrid E28040, Spain.
Upon binding to short specific dsDNA sequences in vitro, the N-terminal WH1 domain of the plasmid DNA replication initiator RepA assembles as amyloid fibres. These are bundles of single or double twisted tubular filaments in which distorted RepA-WH1 monomers are the building blocks. When expressed in Escherichia coli, RepA-WH1 triggers the first synthetic amyloid proteinopathy in bacteria, recapitulating some of the features of mammalian prion diseases: it is vertically transmissible, albeit non-infectious, showing up in at least two phenotypically distinct and interconvertible strains.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!