title: A novel class of secreted hydrophobic proteins is involved in aerial hyphae formation in Streptomyces coelicolor by forming amyloid-like fibrils.
abstract: Streptomycetes exhibit a complex morphological differentiation. After a submerged mycelium has been formed, filaments grow into the air to septate into spores. A class of eight hydrophobic secreted proteins, ChpA-H, was shown to be instrumental in the development of Streptomyces coelicolor. Mature forms of ChpD-H are up to 63 amino acids in length, and those of ChpA-C are larger (+/-225 amino acids). ChpA-C contain two domains similar to ChpD-H, as well as a cell-wall sorting signal. The chp genes were expressed in submerged mycelium (chpE and chpH) as well as in aerial hyphae (chpA-H). Formation of aerial hyphae was strongly affected in a strain in which six chp genes were deleted (DeltachpABCDEH). A mixture of ChpD-H purified from cell walls of aerial hyphae complemented the DeltachpABCDEH strain extracellularly, and it accelerated development in the wild-type strain. The protein mixture was highly surface active, and it self-assembled into amyloid-like fibrils at the water-air interface. The fibrils resembled those of a surface layer of aerial hyphae. We thus conclude that the amyloid-like fibrils of ChpD-H lower the water surface tension to allow aerial growth and cover aerial structures, rendering them hydrophobic. ChpA-C possibly bind ChpD-H to the cell wall.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute (GBB), Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Rick
authors.initials: R
authors.lastname: Rink
authors.forename: Wouter
authors.initials: W
authors.lastname: de Jong
authors.forename: Jeroen
authors.initials: J
authors.lastname: Siebring
authors.forename: Peter
authors.initials: P
authors.lastname: de Vreugd
authors.forename: F G Hidde
authors.initials: FG
authors.lastname: Boersma
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: Han A B
authors.initials: HA
authors.lastname: Wosten
mesh_terms: D000595:Amino Acid Sequence; D057927:Hydrophobic and Hydrophilic Interactions; D025301:Hyphae / Q000254:growth & development*; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D013302:Streptomyces / Q000254:growth & development*
chemical_list: D011506:Proteins