MS (Master of Science)
Date of Award
Committee Chair or Co-Chairs
Cecilia McIntosh, Christopher Pritchett
Rhizobium leguminosarum is a Gram negative nitrogen-fixing soil bacterium. Due to the limited bioavailability of iron, bacteria utilize siderophores that scavenge and bind available iron. The transport of iron-siderophore complexes is achieved by the TonB-ExbB-ExbD complex. We have previously shown that a functional TonB protein is necessary for iron transport by creating ΔtonB mutants and assessing their growth and 55Fe-siderophore transport ability. We attempted to identify and characterize the roles of putative exbB and exbD genes using a similar approach. Growth curves and sequence analyses suggest putative exbB and exbD may be the tolpal-associated genes tolQ and tolR. Phenotypic and sensitivity assays showed mutants do not exhibit the characteristic tol phenotype and are not sensitive to detergents or changes in ionic strength of the growth medium. We also expressed and purified the 120 amino acid fragment of the TonB C-terminus for further physical and chemical characterization.
Thesis - Open Access
Barisic, Valeria, "Characterization of Putative ExbB and ExbD Leads to the Identification of a Potential Tol-Pal System in Rhizobium leguminosarum ATCC 14479" (2015). Electronic Theses and Dissertations. Paper 2489. http://dc.etsu.edu/etd/2489
Copyright by the authors.