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BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm.

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Title: BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm.
Authors: Hobley, Laura1, Ostrowski, Adam1, Rao, Francesco V.1, Bromley, Keith M.2, Porter, Michael1,3, Prescott, Alan R.4, MacPhee, Cait E.2, van Aalten, Daan M. F.1,5, Stanley-Wall, Nicola R.1 n.r.stanleywall@dundee.ac.uk
Source: Proceedings of the National Academy of Sciences of the United States of America. 8/13/2013, Vol. 110 Issue 33, p13600-13605. 6p.
Subjects: Bacillus subtilis, Hydrophobins, Gram-positive bacteria, Biofilms, Microbial exopolysaccharides, Crystal structure
Abstract: Biofilms represent the predominant mode of microbial growth in the natural environment. Bacillus subtilis is a ubiquitous Gram-positive soil bacterium that functions as an effective plant growth-promoting agent. The biofilm matrix is composed of an exopolysaccharide and an amyloid fiber-forming protein, TasA, and assembles with the aid of a small secreted protein, BslA. Here we show that natively synthesized and secreted BslA forms surface layers around the biofilm. Biophysical analysis demonstrates that BslA can self-assemble at interfaces, forming an elastic film. Molecular function is revealed from analysis of the crystal structure of BslA, which consists of an Ig-type fold with the addition of an unusual, extremely hydrophobic "cap" region. A combination of in vivo biofilm formation and in vitro biophysical analysis demonstrates that the central hydrophobic residues of the cap are essential to allow a hydrophobic, nonwetting biofilm to form as they control the surface activity of the BslA protein. The hydrophobic cap exhibits physiochemical properties remarkably similar to the hydrophobic surface found in fungal hydrophobins; thus, BslA is a structurally defined bacterial hydrophobin. We suggest that biofilms formed by other species of bacteria may have evolved similar mechanisms to provide protection to the resident bacterial community. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Biofilms represent the predominant mode of microbial growth in the natural environment. Bacillus subtilis is a ubiquitous Gram-positive soil bacterium that functions as an effective plant growth-promoting agent. The biofilm matrix is composed of an exopolysaccharide and an amyloid fiber-forming protein, TasA, and assembles with the aid of a small secreted protein, BslA. Here we show that natively synthesized and secreted BslA forms surface layers around the biofilm. Biophysical analysis demonstrates that BslA can self-assemble at interfaces, forming an elastic film. Molecular function is revealed from analysis of the crystal structure of BslA, which consists of an Ig-type fold with the addition of an unusual, extremely hydrophobic "cap" region. A combination of in vivo biofilm formation and in vitro biophysical analysis demonstrates that the central hydrophobic residues of the cap are essential to allow a hydrophobic, nonwetting biofilm to form as they control the surface activity of the BslA protein. The hydrophobic cap exhibits physiochemical properties remarkably similar to the hydrophobic surface found in fungal hydrophobins; thus, BslA is a structurally defined bacterial hydrophobin. We suggest that biofilms formed by other species of bacteria may have evolved similar mechanisms to provide protection to the resident bacterial community. [ABSTRACT FROM AUTHOR]
ISSN:00278424
DOI:10.1073/pnas.1306390110