title: Isolation, characterization, and aggregation of a structured bacterial matrix precursor.
abstract: Biofilms 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 α-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 β-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.
authors: Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Liraz
authors: L
authors: Chai
authors: Diego
authors: D
authors: Romero
authors: Can
authors: C
authors: Kayatekin
authors: Barak
authors: B
authors: Akabayov
authors: Hera
authors: H
authors: Vlamakis
authors: Richard
authors: R
authors: Losick
authors: Roberto
authors: R
authors: Kolter
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry; D000682:Amyloid / Q000737:chemistry / Q000302:isolation & purification / Q000648:ultrastructure; D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D018441:Biofilms; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D018625:Microscopy, Atomic Force; D010316:Particle Size; D055503:Protein Multimerization; D012542:Scattering, Radiation; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D000682:Amyloid; D001426:Bacterial Proteins; D016326:Extracellular Matrix Proteins; C119938:TasA protein, Bacillus subtilis; C011934:mica
keywords: Amyloid Precursor Protein; Bacillus; Biofilm; Extracellular Matrix; Extracellular Matrix Proteins; Microbiology; Protein Aggregation
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