title: Surface modification using interfacial assembly of the Streptomyces chaplin proteins.
abstract: The chaplin proteins are instrumental in the formation of reproductive aerial structures by the filamentous bacterium Streptomyces coelicolor. They lower the water surface tension thereby enabling aerial growth. In addition, chaplins provide surface hydrophobicity to the aerial hyphae by assembling on the cell surface into an amphipathic layer of amyloid fibrils. We here show that mixtures of cell wall-extracted chaplins can be used to modify a variety of hydrophilic and hydrophobic surfaces in vitro thereby changing their nature. Assembly on glass leads to a protein coating that makes the surface hydrophobic. Conversely, the assembly of chaplins on hydrophobic surfaces renders them hydrophilic. Furthermore, we show that chaplins can stabilize emulsions of oil into water and have an unprecedented surface activity at high pH. Interestingly, this high surface activity coincides with the interfacial assembly of chaplins into a semi-liquid membrane, as opposed to the rigid membrane formed at neutral pH. This semi-liquid membrane possibly represents a trapped intermediate in the assembly process towards the more rigid amyloidal conformation. Taken together, our data shows that chaplins are suitable candidate proteins for a wide range of biotechnological applications.
authors.affiliation: Ocean Ecosystems, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
authors.forename: David Matthias
authors.initials: DM
authors.lastname: Ekkers
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Federica
authors.initials: F
authors.lastname: Galli
authors.forename: Eize
authors.initials: E
authors.lastname: Stamhuis
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D055503:Protein Multimerization; D048372:Streptomyces coelicolor / Q000235:genetics* / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins