Generating bio-organic metal surfaces with modified surface properties using the type IV pilus of Pseudomonas aeruginosa

• Author / Creator

  Davis, Elisabeth M

• Pseudomonas aeruginosa is an ubiquitiously distributed organism that functions as an aggressive opportunistic pathogen that has evolved to survive in many hosts in the plant and animal kingdoms and constitutes an important causative agent of nosocomial infections in terms of human health and serves as a major source of biofouling of surfaces in our environment. An important factor in the success of P. aeruginosa as a pathogen is its ability to colonize and move across various biotic and abiotic surfaces using its Type IV pilus (T4P). Binding is mediated by the receptor binding domain (RBD) and synthetic forms of the RBD irreversibly bind to stainless steel with high affinity in the absence of hydrophobic interactions. It was determined that the high affinity of the RBD for metal surfaces is mediated by electron sharing between the peptide and the metal surface electrons. Electron sharing results in the formation of a novel organo-metallic state of matter and creates new bio-organic metals that have altered surface properties (electron work function, adhesive force, corrosion, friction, propensity for biofilm formation) compared to unaltered metal. Chiral variants of the RBD peptide interact differentially with metal surfaces, suggesting that metal surfaces have chiral structural elements that are differentially recognized by the peptides. The addition of a PEG molecule to the RBD generates a facile, single-step versatile surface coating that increases the hardness of metals (304 stainless steel, titanium, A2024 aluminum) while decreasing corrosion, friction, and the propensity for colonization by bacteria. It was also demonstrated that the T4P of P. aeruginosa is an insulated molecular nanowire that facilitates electron removal from metal surfaces and can sustain the flow of high currents of up to several milliamps. The T4P also acts as a sensor, modulating current flow in response to external stimuli such as Pseudomonas autoinducers and ultra-violet light, and switches between conformations that permit or restricts electron transfer. The results in this study present attractive possibilities in industry for the facile generation of versatile surface engineering approaches for metals using non-toxic materials. The novel nanowire and environmental sensor aspects of T4P function have important implications in the pathogenesis of P. aeruginosa and further demonstrate the complexity and multifunctionality of the T4P.

• Subjects / Keywords

  • Electron transfer
  • Type IV pili
  • Surface modification

• Graduation date

  Spring 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3CK51

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.