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

Laura Hobley, Adam Ostrowski, Francesco V. Rao, Keith M. Bromley, Michael Porter, Alan R. Prescott, Cait E. Macphee, Daan M. F. van Aalten, Nicola R. Stanley-Wall (Lead / Corresponding author)

    Research output: Contribution to journalArticle

    113 Citations (Scopus)

    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.
    Original languageEnglish
    Pages (from-to)13600-13605
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume110
    Issue number33
    DOIs
    Publication statusPublished - 13 Aug 2013

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    Biofilms
    Bacillus subtilis
    Proteins
    Gram-Positive Bacteria
    Growth
    Amyloid
    Soil
    Bacteria

    Cite this

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    title = "BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm",
    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.",
    author = "Laura Hobley and Adam Ostrowski and Rao, {Francesco V.} and Bromley, {Keith M.} and Michael Porter and Prescott, {Alan R.} and Macphee, {Cait E.} and {van Aalten}, {Daan M. F.} and Stanley-Wall, {Nicola R.}",
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    BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm. / Hobley, Laura; Ostrowski, Adam; Rao, Francesco V.; Bromley, Keith M.; Porter, Michael; Prescott, Alan R.; Macphee, Cait E.; van Aalten, Daan M. F.; Stanley-Wall, Nicola R. (Lead / Corresponding author).

    In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 110, No. 33, 13.08.2013, p. 13600-13605.

    Research output: Contribution to journalArticle

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    T1 - BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm

    AU - Hobley, Laura

    AU - Ostrowski, Adam

    AU - Rao, Francesco V.

    AU - Bromley, Keith M.

    AU - Porter, Michael

    AU - Prescott, Alan R.

    AU - Macphee, Cait E.

    AU - van Aalten, Daan M. F.

    AU - Stanley-Wall, Nicola R.

    PY - 2013/8/13

    Y1 - 2013/8/13

    N2 - 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.

    AB - 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.

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