Citation:
Abstract:
Biofilms are aggregates of microbial cells that form on surfaces and at interfaces and are encased in an extracellular matrix. In biofilms made by the soil bacterium Bacillus subtilis, the protein TapA mediates the assembly of the functional amyloid protein TasA into extracellular fibers and it also anchors these fibers to the cell surface. Here we used circular dichroism and NMR to show that, unlike the structured TasA, TapA is disordered. In addition, TapA is composed of two weakly interacting domains, a disordered C‐terminal domain and a more structured N‐terminal domain. These two domains also exhibited different structural changes in response to changes in external conditions, such as increased temperatures and the presence of lipid vesicles. While the two TapA domains weakly interacted in solution, their cooperative interaction with lipid vesicles prevented the vesicles' disruption, that was otherwise observed in the presence of the C‐terminal domain alone. Our findings therefore suggest that the two‐domain composition of TapA is important for its interaction with a single or with multiple partners in the extracellular matrix in biofilms.