title: Chaplins of Streptomyces coelicolor self-assemble into two distinct functional amyloids.
abstract: Chaplins are small, secreted proteins of streptomycetes that play instrumental roles in the formation of aerial hyphae and attachment of hyphae to surfaces. Here we show that the purified proteins self-assemble at a water/air interface into an asymmetric and amphipathic protein membrane that has an amyloid nature. Cryo-tomography reveals that the hydrophilic surface is relatively smooth, while the hydrophobic side is highly structured and characterized by the presence of small fibrils, which are similar to those observed on the surfaces of aerial hyphae. Interestingly, our work also provides evidence that chaplins in solution assemble into amyloid fibrils with a distinct morphology. These hydrophilic fibrils strongly resemble the structures known to be involved in attachment of Streptomyces hyphae to surfaces. These data for the first time show the assembly of bacterial proteins into two distinct amyloid structures that have different and relevant functions in vivo.
authors.affiliation: Electron Microscopy, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands. Electronic address: marcel.bokhove@gmail.com.
authors.forename: Marcel
authors.initials: M
authors.lastname: Bokhove
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Wouter
authors.initials: W
authors.lastname: de Jong
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: Egbert J
authors.initials: EJ
authors.lastname: Boekema
authors.forename: Gert T
authors.initials: GT
authors.lastname: Oostergetel
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000648:ultrastructure*; D001426:Bacterial Proteins / Q000737:chemistry / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D055032:Electron Microscope Tomography; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D048372:Streptomyces coelicolor; D013499:Surface Properties
chemical_list: D000682:Amyloid; D001426:Bacterial Proteins
keywords: Amyloid; Chaplin; Cross-beta structure; Cryo-electron tomography; Electron diffraction; Streptomyces