title: Expression and purification of a functionally active class I fungal hydrophobin from the entomopathogenic fungus Beauveria bassiana in E. coli.
abstract: Hydrophobins represent a class of unique fungal proteins that have low molecular mass, are cysteine rich, and can self-assemble into two-dimensional arrays at water/air interfaces. These highly surface-active proteins are able to decrease the surface tension of water, thus allowing fungal structures to penetrate hydrophobic-hydrophilic barriers. Due to their unusual biophysical properties, hydrophobins have been suggested for use in a wide range of biotechnological applications. Here we describe a simple method for producing a functionally active class I hydrophobin derived from the entomopathogenic fungus, Beauveria bassiana, in an E. coli host. N-terminal modifications were required for proper expression and purification, and the hydrophobin was expressed as a fusion partner to a cleavable N-terminus chitin-binding domain-intein construct. The protein was purified and reconstituted from E. coli inclusion bodies. Self-assembly of the recombinant hydrophobin was followed kinetically using a thioflavin T fluorescence binding assay, and contact angle measurements of purified recombinant hydrophobin protein (mHyd2) films on a variety of substrata demonstrated its surface modification ability, which remained stable for at least 4 months. Filament or fibril-like structures were imaged using atomic force and transmission electron microscopy. These data confirmed the functional properties of the purified protein and indicate amino acid flexibility at the N-terminus, which can be exploited for various applications of these proteins.
authors.affiliation: Department of Microbiology and Cell Science, University of Florida, Museum Rd., Gainesville, FL 32611, USA.
authors.forename: Brett H
authors.initials: BH
authors.lastname: Kirkland
authors.forename: Nemat O
authors.initials: NO
authors.lastname: Keyhani
mesh_terms: D052982:Beauveria / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D005656:Fungal Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins