Page 42 - Hormel Report 2021

Bin Liu, Ph.D.
“Transcription is the central step in the expression of genes, and a major mechanism for controlling the expression of a gene is to regulate its tran- scription. Transcription is regulated by various transcription factors. Many human diseases and disorders are associated with misregulation of transcription and mutations of transcription factors, including cancer, autoimmunity, neuro- logical disorders, developmental disorders,
diabetes, cardiovascular disease, and obesity.”
Bin Liu
42 | THE HORMEL INSTITUTE // UNIVERSITY OF MINNESOTA Transcription and Gene Regulation
SECTION LEADER / ASSISTANT PROFESSOR
Our overall goal is to provide a structural basis of the initiation, elongation and termination of transcription and their
regulations in bacteria. We shall study the for- mation of the transcription initiation complexes with various sigma factors, the transition from initiation to elongation and termination phases, the translocation of the RNA polymerase (RNAP) on template DNA, and the regulation of the
RNAP by transcription factors at various stages of transcription. This objective will be achieved
by determining the structures of the RNAP complexed with functionally associated proteins and appropriate DNA/RNA substrates captured at various steps in the processes, using cryo- electron microscopy and X-ray crystallography, as well as by appropriate biochemical experiments.
To elucidate the mechanisms of transcription initiation with alternative sigma factors
In bacteria, there are seven well identified sigma factors. σ70 is the primary sigma factor, which initiates the expression of most genes, while other six ones are the alternative sigma factors
in response to different environmental conditions. Previous structural studies of the holoenzyme and transcription initiation complex (TIC) with σ70, σ54, σ38, and σ24 have shed light on RNAP-medi- ated gene expressions under normal conditions, under nitrogen-limited conditions, under starva- tion stress, and under heat stress, respectively. However, the structures of those complexes with σ32, σ28, and σ19 are still unknown. These factors are recruited under different stress conditions