Degree Name

MS (Master of Science)



Date of Award


Committee Chair or Co-Chairs

Ranjan Chakraborty

Committee Members

Christopher Pritchett, Dhirendra Kumar


Rhizobium leguminosarum is a gram-negative soil bacterium that requires iron for survival. However, iron becomes insoluble in the presence of oxygen at physiological pH. In response, Rhizobia species have used siderophore mediated iron transport systems to meet their iron requirements. R. leguminosarum ATCC 14479 produces the trihydroxymate siderophore vicibactin and we hypothesize that the import of the ferric iron-vicibactin complex is energized by the TonB-ExbB-ExbD system. Here, we have identified a putative tonB gene. A tonB mutant was created and compared with wild type in its ability to transport 55Fe-vicibactin. Also, the putative TonB of R. leguminosarum ATCC 14479 is interesting due to its estimated size compared to the TonB of E. coli.. Many groups have attempted structural analysis of the C-terminus of TonB in E. col with inconsistent results. We were successful in expressing 2 different sized TonB C-terminals (120 and 200 amino acids) using pET17b in E. coli.

Document Type

Thesis - unrestricted


Copyright by the authors.