4bhu
Crystal structure of BslA - A bacterial hydrophobin
Structural highlights
FunctionBSLA_BACSU Involved in biofilm formation (PubMed:18978066, PubMed:21742882). Self-polymerizes and forms a layer on the surface of biofilms that confers hydrophobicity to the biofilm (PubMed:22571672, PubMed:23904481). The layer is stable and capable of resistance to high mechanical force compression (PubMed:28701036). Required for complex colony architecture (PubMed:18978066). May function synergistically with exopolysaccharides and TasA amyloid fibers to facilitate the assembly of the biofilm matrix (PubMed:21742882).[1] [2] [3] [4] [5] Publication Abstract from PubMedBiofilms 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. BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm.,Hobley L, Ostrowski A, Rao FV, Bromley KM, Porter M, Prescott AR, Macphee CE, van Aalten DM, Stanley-Wall NR Proc Natl Acad Sci U S A. 2013 Jul 31. PMID:23904481[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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