title: Genetically-Tunable Mechanical Properties of Bacterial Functional Amyloid Nanofibers.
abstract: Bacterial biofilms are highly ordered, complex, dynamic material systems including cells, carbohydrates, and proteins. They are known to be resistant against chemical, physical, and biological disturbances. These superior properties make them promising candidates for next generation biomaterials. Here we investigated the morphological and mechanical properties (in terms of Young's modulus) of genetically-engineered bacterial amyloid nanofibers of Escherichia coli (E. coli) by imaging and force spectroscopy conducted via atomic force microscopy (AFM). In particular, we tuned the expression and biochemical properties of the major and minor biofilm proteins of E. coli (CsgA and CsgB, respectively). Using appropriate mutants, amyloid nanofibers constituting biofilm backbones are formed with different combinations of CsgA and CsgB, as well as the optional addition of tagging sequences. AFM imaging and force spectroscopy are used to probe the morphology and measure the Young's moduli of biofilm protein nanofibers as a function of protein composition. The obtained results reveal that genetically-controlled secretion of biofilm protein components may lead to the rational tuning of Young's moduli of biofilms as promising candidates at the bionano interface.
authors.affiliation: Department of Mechanical Engineering, Bilkent University , Ankara 06800, Turkey.|Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.|National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey.
authors.forename: M Tarek
authors.initials: MT
authors.lastname: Abdelwahab
authors.affiliation: Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.|National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey.
authors.forename: Ebuzer
authors.initials: E
authors.lastname: Kalyoncu
authors.affiliation: Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.|National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey.
authors.forename: Tugce
authors.initials: T
authors.lastname: Onur
authors.affiliation: Department of Mechanical Engineering, Bilkent University , Ankara 06800, Turkey.|Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.|National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey.
authors.forename: Mehmet Z
authors.initials: MZ
authors.lastname: Baykara
authors.affiliation: Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.|National Nanotechnology Research Center (UNAM), Bilkent University , Ankara 06800, Turkey.
authors.forename: Urartu Ozgur Safak
authors.identifier: 0000-0002-5272-1876
authors.initials: UOS
authors.lastname: Seker
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000235:genetics; D058227:Amyloidogenic Proteins / Q000737:chemistry* / Q000235:genetics; D018441:Biofilms; D055119:Elastic Modulus; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D018625:Microscopy, Atomic Force; D009154:Mutation; D057139:Nanofibers / Q000737:chemistry*
chemical_list: D000682:Amyloid; D058227:Amyloidogenic Proteins; C109182:CsgB protein, E coli; D029968:Escherichia coli Proteins; C489688:csgA protein, E coli