Chai, LirazRomero, DiegoKayatekin, CanAkabayov, BarakVlamakis, HeraLosick, RichardKolter, Roberto2019-10-052013Chai, Liraz, Diego Romero, Can Kayatekin, Barak Akabayov, Hera Vlamakis, Richard Losick, and Roberto Kolter. 2013. “Isolation, Characterization, and Aggregation of a Structured Bacterial Matrix Precursor.” Journal of Biological Chemistry 288 (24): 17559–68. https://doi.org/10.1074/jbc.m113.453605.0021-92581083-351Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:41483163Biofilms are surface-associated groups of microbial cells that are embedded in an extracellular matrix (ECM). The ECM is a network of biopolymers, mainly polysaccharides, proteins, and nucleic acids. ECM proteins serve a variety of structural roles and often form amyloid-like fibers. Despite the extensive study of the formation of amyloid fibers from their constituent subunits in humans, much less is known about the assembly of bacterial functional amyloid-like precursors into fibers. Using dynamic light scattering, atomic force microscopy, circular dichroism, and infrared spectroscopy, we show that our unique purification method of a Bacillus subtilis major matrix protein component results in stable oligomers that retain their native alpha-helical structure. The stability of these oligomers enabled us to control the external conditions that triggered their aggregation. In particular, we show that stretched fibers are formed on a hydrophobic surface, whereas plaque-like aggregates are formed in solution under acidic pH conditions. TasA is also shown to change conformation upon aggregation and gain some beta-sheet structure. Our studies of the aggregation of a bacterial matrix protein from its subunits shed new light on assembly processes of the ECM within bacterial biofilms.en-USJournal Article2019-10-0510.1074/jbc.M113.453605