Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Wang, Yong

Committee Member

Savin, Mary C.

Second Committee Member

Heyes, Colin D.

Keywords

Silver; Antibiotics; Cell biology; Molecular biology; DNA

Abstract

Silver nanoparticles (AgNPs) and ions (Ag+) can be the new generation of antibiotics due to their antimicrobial effects against bacteria and other microbes. Many studies have shown that AgNPs and suppress the growth of bacteria and damage the cell walls of the microbes; therefore, treating bacterial cells with AgNPs may be a promising method to terminate multi-resistant bacteria. In this work, the effect of AgNPs with two different surface coatings on the spatial reorganization of histone-like nucleoid structuring (H-NS) proteins in Escherichia coli bacteria was investigated using quantitative super-resolution fluorescence microscopy to understand the toxicity and antimicrobial mechanism of AgNPs. H-NS protein is one of the major DNA-associated proteins in bacteria, serving as a universal regulator. AgNPs inhibited the bacterial growth, changed the morphology of bacteria, and disturbed the membrane of bacteria. More importantly, treating bacteria with AgNPs led to the spatial reorganization of H-NS proteins because of the released ions and changes in the clustering behavior of H-NS proteins. Spatial reorganization at the molecular level was quantified using algorithms based on Voronoi diagrams and tessellation. In addition, ions released from AgNPs led to the formation of larger and denser clusters of H-NS protein centered in the bacteria. As H-NS is a DNA binding protein, denser clustering of H-NS proteins is likely related to the DNA condensation, which was reported previously in the literature.

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