title: Self-assembly of the hydrophobin SC3 proceeds via two structural intermediates.
abstract: Hydrophobins self assemble into amphipathic films at hydrophobic-hydrophilic interfaces. These proteins are involved in a broad range of processes in fungal development. We have studied the conformational changes that accompany the self-assembly of the hydrophobin SC3 with polarization-modulation infrared reflection absorption spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and circular dichroism, and related them to changes in morphology as observed by electron microcopy. Three states of SC3 have been spectroscopically identified previously as follows: the monomeric state, the alpha-helical state that is formed upon binding to a hydrophobic solid, and the beta-sheet state, which is formed at the air-water interface. Here, we show that the formation of the beta-sheet state of SC3 proceeds via two intermediates. The first intermediate has an infrared spectrum indistinguishable from that of the alpha-helical state of SC3. The second intermediate is rich in beta-sheet structure and has a featureless appearance under the electron microscope. The end state has the same secondary structure, but is characterized by the familiar 10-nm-wide rodlets.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Marcel L
authors.initials: ML
authors.lastname: de Vocht
authors.forename: Ilya
authors.initials: I
authors.lastname: Reviakine
authors.forename: Wolf-Peter
authors.initials: WP
authors.lastname: Ulrich
authors.forename: Wilma
authors.initials: W
authors.lastname: Bergsma-Schutter
authors.forename: Han A B
authors.initials: HA
authors.lastname: Wösten
authors.forename: Horst
authors.initials: H
authors.lastname: Vogel
authors.forename: Alain
authors.initials: A
authors.lastname: Brisson
authors.forename: Joseph G H
authors.initials: JG
authors.lastname: Wessels
authors.forename: George T
authors.initials: GT
authors.lastname: Robillard
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry; D002942:Circular Dichroism; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry*; D008854:Microscopy, Electron; D017433:Protein Structure, Secondary; D013055:Spectrophotometry, Infrared
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins