Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Biomedical Sciences

Content Description

1 online resource (x, 178 pages) : color illustrations.

Dissertation/Thesis Chair

Joseph T Wade

Committee Members

Todd A Gray, Randall H Morse, Anil K Ojha, Pan TX Li


Antitermination, Molecular genetics, Termination, Transcription, Escherichia coli, Genetic transcription, Genetic regulation, Genetic translation, RNA polymerases

Subject Categories

Genetics | Microbiology | Molecular Biology


Transcription termination factor Rho is an essential protein in Escherichia coli and related bacteria. The primary function of Rho is to clear unproductive RNA polymerases from the DNA template to minimize negative effects associated with uncontrolled transcription. Although most of the Rho termination events are constitutive, premature Rho-mediated termination was observed at 3% of all affected transcripts indicating active regulation of Rho activity. In this work, we investigated the regulatory mechanism behind premature Rho-dependent transcription termination in two unrelated genes: suhB and topAI. We show that in both cases transcription is terminated inside the coding gene as a consequence of translational repression under normal growth conditions. The repression of translation at suhB and topAI is different at the mechanistic level. Interestingly, both genes are adapted to sense the translational status of the cell in order to regulate expression. Both genes utilize Rho as a second layer of repression when needed. This emphasizes the importance of Rho in the surveillance of unproductive transcription, and how this feature can be utilized in gene regulation. We also established an in vivo Rho activity assay that is suitable for large-scale high-throughput molecule screen. Future applications of this assay might yield novel