8aur
From Proteopedia
Cryo-EM structure of a TasA fibre
Structural highlights
FunctionTASA_BACSU TasA is the major protein component of the biofilm extracellular matrix (PubMed:16430696, PubMed:20080671). It forms amyloid fibers that bind cells together in the biofilm (PubMed:20080671). Exhibits an antibacterial activity against a variety of Gram-positive and Gram-negative bacteria (PubMed:10049401). In laboratory strains, is also involved in proper spore coat assembly (PubMed:10368135).[1] [2] [3] [4] Publication Abstract from PubMedMany bacteria in nature exist in multicellular communities termed biofilms, where cells are embedded in an extracellular matrix that provides rigidity to the biofilm and protects cells from chemical and mechanical stresses. In the Gram-positive model bacterium Bacillus subtilis, TasA is the major protein component of the biofilm matrix, where it has been reported to form functional amyloid fibres contributing to biofilm structure and stability. Here, we present electron cryomicroscopy structures of TasA fibres, which show that, rather than forming amyloid fibrils, TasA monomers assemble into fibres through donor-strand exchange, with each subunit donating a beta-strand to complete the fold of the next subunit along the fibre. Combining electron cryotomography, atomic force microscopy, and mutational studies, we show how TasA fibres congregate in three dimensions to form abundant fibre bundles that are essential for B. subtilis biofilm formation. Our study explains the previously observed biochemical properties of TasA and shows how a bacterial extracellular globular protein can assemble from monomers into beta-sheet-rich fibres, and how such fibres assemble into bundles in biofilms. Donor-strand exchange drives assembly of the TasA scaffold in Bacillus subtilis biofilms.,Bohning J, Ghrayeb M, Pedebos C, Abbas DK, Khalid S, Chai L, Bharat TAM Nat Commun. 2022 Nov 18;13(1):7082. doi: 10.1038/s41467-022-34700-z. PMID:36400765[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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