Date of Award


Degree Type


Degree Name

Master of Science




Biology (MS)

First Advisor/Chairperson

Josh Sharp


One way in which bacteria are able to sense and respond to environmental changes is through two-component systems (TCSs). TCSs are composed of a membrane bound sensor protein that can pick up an environmental cue that then activates a cytoplasmic response regulator. The response regulator can, in turn, bind DNA and either activate or repress transcription of specific genes. One such TCS is the CrbS/R system, which is conserved among γ-Proteobacteria. This TCS has been shown to control the acsA gene, which is involved in acetate metabolism, however, other genes potentially under this TCSs’ control are unknown. The aim of this study was to further elucidate genes under the control of the CrbS/R TCS. RNAseq analysis showed us that acsA and actP, which encodes an acetate permease, which is responsible for bringing acetate across the cell membrane, are upregulated by the TCS. Furthermore, in P. aeruginosa and P. entomophila we were able to determine that genes involved in nitrogen metabolism are downregulated by CrbS. We did not see this regulation by CrbR. It appears that CrbR is solely dedicated to acetate metabolism pathway and CrbR itself is not part of a larger regulator network. CrbS, however, seems to be involved in multiple metabolic pathways, likely by interacting with multiple response regulatory proteins. While RNAseq allows us to determine genes controlled directly or indirectly by the CrbS/R TCS, a method called ChIPseq will allow us to determine genes that are controlled directly by the response regulator, CrbR.

Access Type

Open Access

Justification for Restricting Access

This thesis contains data that will be submitted for publication in a peer reviewed journal.

Available for download on Tuesday, July 29, 2025