title: Amyloid formation modulates the biological activity of a bacterial protein.
abstract: The aggregation of proteins into amyloid fibrils is the hallmark feature of a group of late-onset degenerative diseases including Alzheimer, Parkinson, and prion diseases. We report here that microcin E492, a peptide naturally produced by Klebsiella pneumoniae that kills bacteria by forming pores in the cytoplasmic membrane, assembles in vitro into amyloid-like fibrils. The fibrils have the same structural, morphological, tinctorial, and biochemical properties as the aggregates observed in the disease conditions. In addition, we found that amyloid formation also occurs in vivo where it is associated with a loss of toxicity of the protein. The finding that microcin E492 naturally exists both as functional toxic pores and as harmless fibrils suggests that protein aggregation into amyloid fibrils is an evolutionarily conserved property of proteins that can be successfully employed by bacteria to fulfill specific physiological needs.
authors.affiliation: Department of Neurology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bieler
authors.forename: Lisbell
authors.initials: L
authors.lastname: Estrada
authors.forename: Rosalba
authors.initials: R
authors.lastname: Lagos
authors.forename: Marcelo
authors.initials: M
authors.lastname: Baeza
authors.forename: Joaquín
authors.initials: J
authors.lastname: Castilla
authors.forename: Claudio
authors.initials: C
authors.lastname: Soto
mesh_terms: D000682:Amyloid / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001430:Bacteriocins / Q000737:chemistry / Q000378:metabolism*; D019281:Dimerization; D019143:Evolution, Molecular; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000737:chemistry; D008854:Microscopy, Electron
chemical_list: D000682:Amyloid; D001426:Bacterial Proteins; D001430:Bacteriocins; C020411:microcin