Ph.D. Georgia State University
Molecular Genetics & Microbiology
MGB/Gene expression and RNA polymerase elongation kinetics
Bacterial RNA polymerase transcription rates depend on the nucleic acid sequences transcribed and the protein factors that associate with the elongation complex. In Esherichia coli, RNA polymerase transcribes general mRNA at a rate of about 40 – 45 nucleotides per second, in contrast, the rate of transcription on ribosomal operons is about 90 nucleotides per second. The elevation of the transcription rate, seen within the ribosomal operons, is the result of an operon specific nucleic acid sequence and protein factors that associate with RNA polymerase during transcription. In the case of the ribosomal operons, the consequential effect of this significant rate increase is elevation of ribosomal gene expression.
In our lab, we are focusing our studies on the mechanisms by which the prokaryotic cell is able to fine-tune the expression of its genes through modulation of RNA polymerase elongation rates. Therefore, one of our goals is to identify specific nucleic acid sequences and protein factors that serve to influence prokaryotic RNA polymerase elongation rates. This research attempts to understand how these factors affect the in vivo elongation kinetics of RNA polymerase and ultimately the regulation of gene expression. Recently, we identified two transcription factors that influence RNA polymerase transcription rates in vivo. A second area of study in our lab involves the analysis of the influence of various RNA polymerase mutants on in vivo transcription rates. These studies will define the specific regions within RNA polymerase that modulate transcription elongation rates and aid in correlating these regions with the 3D structure of the polymerase. The final area of research in our lab centers on proteins that have dual roles. Specifically, we have an interest in prokaryotic cellular proteins shared between the processes of transcription and translation. We are currently attempting to elucidate the structural characteristics of these proteins that make their dual functionality possible. Our hope is to better understand how the complex cellular machines of translation and transcription communicate to influence gene expression.