Related Experiment Video

Updated: Mar 23, 2026

Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis
10:03

Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis

Published on: July 16, 2008

28.7K

RepA-WH1 prionoid: Clues from bacteria on factors governing phase transitions in amyloidogenesis

Rafael Giraldo1, Cristina Fernández1, María Moreno-del Álamo1

  • 1a Department of Cellular & Molecular Biology , Centro de Investigaciones Biológicas - CSIC , Madrid , Spain.

Prion
|April 5, 2016
PubMed

Insights

Bacterial RepA-WH1 proteins form prionoids that cause transmissible proteinopathies. The Hsp70 chaperone DnaK controls the propagation of these bacterial amyloids, offering insights into protein misfolding.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Rep proteins initiate bacterial plasmid DNA replication via structural changes and dimer dissociation.
  • Amyloidogenesis of the RepA N-terminal domain (RepA-WH1) is DNA-sequence-dependent and occurs in vivo.
  • RepA-WH1 forms amyloid fibers from distorted monomers into tubular protofilaments.

Purpose of the Study:

  • To investigate the in vivo and in vitro amyloidogenesis of bacterial RepA-WH1.
  • To understand the mechanism of prionoid transmission and conformational imprinting in bacteria.
  • To explore the role of chaperones in regulating RepA-WH1 aggregate dynamics.

Main Methods:

  • In vitro amyloid formation assays.
  • In vivo studies in E. coli using microfluidics to track intracellular dynamics.
  • Construction of synthetic prions by chimera engineering.

Main Results:

  • RepA-WH1 induces a transmissible, non-infectious amyloid proteinopathy in E. coli.
  • Two distinct RepA-WH1 aggregate strains (cytotoxic particles vs. hydrogel) were observed in bacterial lineages.
  • The Hsp70 chaperone DnaK regulates the phase transition and propagation of RepA-WH1 prionoids.
  • A synthetic prion, [REP-PSI(+)], was created, showing phenotypic variants.

Conclusions:

  • RepA-WH1 functions as a bacterial prionoid, influencing DNA replication and cellular health.
  • Bacterial amyloid dynamics are modulated by chaperones, impacting prionoid propagation.
  • This study provides a model for understanding protein amyloidogenesis and prionoid behavior in a synthetic bacterial system.
Keywords:
Hsp70 chaperoneRepA-WH1amyloid polymorphismamyloid proteinopathybacterial prionoidphase transitions

More Related Videos

Investigating the Spreading and Toxicity of Prion-like Proteins Using the Metazoan Model Organism C. elegans12:57

Investigating the Spreading and Toxicity of Prion-like Proteins Using the Metazoan Model Organism C. elegans

Published on: January 8, 2015

16.7K
Protein Misfolding Cyclic Amplification of Prions10:12

Protein Misfolding Cyclic Amplification of Prions

Published on: November 7, 2012

20.3K

Related Concept Videos

Amyloid Fibrils03:03

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins.  Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils. 
Amyloid deposits were observed as early as 1639 in the liver and the spleen.   In 1854, Rudolph Virchow performed iodine staining,...
12.8K
Amyloid Fibrils03:03

Amyloid Fibrils

6.9K
Bacterial Protein Maturation01:26

Bacterial Protein Maturation

Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...
683
Protein Folding01:25

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
12.3K
Protein Folding01:22

Protein Folding

Overview
130.1K
Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
20.7K