title: The assembly of individual chaplin peptides from Streptomyces coelicolor into functional amyloid fibrils.
abstract: The self-association of proteins into amyloid fibrils offers an alternative to the natively folded state of many polypeptides. Although commonly associated with disease, amyloid fibrils represent the natural functional state of some proteins, such as the chaplins from the soil-dwelling bacterium Streptomyces coelicolor, which coat the aerial mycelium and spores rendering them hydrophobic. We have undertaken a biophysical characterisation of the five short chaplin peptides ChpD-H to probe the mechanism by which these peptides self-assemble in solution to form fibrils. Each of the five chaplin peptides produced synthetically or isolated from the cell wall is individually surface-active and capable of forming fibrils under a range of solution conditions in vitro. These fibrils contain a highly similar cross-β core structure and a secondary structure that resembles fibrils formed in vivo on the spore and mycelium surface. They can also restore the growth of aerial hyphae to a chaplin mutant strain. We show that cysteine residues are not required for fibril formation in vitro and propose a role for the cysteine residues conserved in four of the five short chaplin peptides.
authors.affiliation: Department of Chemical and Biomolecular Engineering and the Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Sawyer
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Maria
authors.initials: M
authors.lastname: Haas
authors.forename: Bhavna
authors.initials: B
authors.lastname: Hurgobin
authors.forename: Sally L
authors.initials: SL
authors.lastname: Gras
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D002942:Circular Dichroism; D019295:Computational Biology; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013171:Spores, Bacterial / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000378:metabolism*; D040681:Structural Homology, Protein; D014269:Trifluoroacetic Acid; D014961:X-Ray Diffraction
chemical_list: D000682:Amyloid; D001426:Bacterial Proteins; D010455:Peptides; D012996:Solutions; D014269:Trifluoroacetic Acid