title: Amyloid-like properties of bacterial inclusion bodies.
abstract: Bacterial inclusion bodies are major bottlenecks in protein production, narrowing the spectrum of relevant polypeptides obtained by recombinant DNA. While regarded as amorphous deposits formed by passive and rather unspecific precipitation of unfolded chains, we prove here that they are instead organized aggregates sharing important structural and biological features with amyloids. By using an Escherichia coli beta-galactosidase variant, we show that aggregation does not necessarily require unfolded polypeptide chains but rather depends on specific interactions between solvent-exposed hydrophobic stretches in partially structured species. In addition, purified inclusion bodies are efficient and highly selective nucleation seeds, promoting deposition of soluble homologous but not heterologous polypeptides in a dose-dependent manner. Finally, inclusion bodies bind amyloid-diagnostic dyes, which, jointly with Fourier transform infra red spectroscopy data, indicates a high level of organized intermolecular beta-sheet structure. The evidences of amyloid-like structure of bacterial inclusion bodies, irrespective of potential applications in bioprocess engineering, prompts the use of bacterial models to explore the molecular determinants of protein aggregation by means of simple biological systems.
authors.affiliation: Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Carrió
authors.forename: Nuria
authors.initials: N
authors.lastname: González-Montalbán
authors.forename: Andrea
authors.initials: A
authors.lastname: Vera
authors.forename: Antonio
authors.initials: A
authors.lastname: Villaverde
authors.forename: Salvador
authors.initials: S
authors.lastname: Ventura
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D002479:Inclusion Bodies / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D012995:Solubility; D013050:Spectrometry, Fluorescence; D001616:beta-Galactosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000682:Amyloid; D036022:Capsid Proteins; C442501:VP1 protein, Foot-and-mouth disease virus; D001616:beta-Galactosidase