Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Janina Lewis


The facultative anaerobe, Escherichia coli and the obligate anaerobe, Porphyromonas gingivalis are two bacteria that reside in our body. Although they reside in separate environments, they are both subject to hydrogen peroxide stress and have mechanisms to regulate the stress. OxyR is the primary transcriptional regulator/sensor of oxidative stress response caused by hydrogen peroxide. OxyR in P. gingivalis is not well-characterized compared to OxyR in E. coli. We sought to characterize and compare the two forms of OxyR in order to gain a better understanding of the protein. We determined the oligomeric state of both proteins: primarily a tetramer for E. coli and primarily a tetramer for P. gingivalis OxyR.. We demonstrated DNA binding with E. coli OxyR, indicating purification of the functional form of E. coli OxyR.Through pulldown assays we discovered potential novel binding targets, mobB for E. coli OxyR and PG1209 for P. gingivalis OxyR. Many of the other targets corresponded to intergenic regions within genes, which may pertain to small RNAs or small proteins. These results show that OxyR in E. coli and P. gingivalis has novel function and properties indicating an expanded role in addition to the well-characterized oxidative stress response.


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