Graduate Studies


First Advisor

Limei Zhang

Date of this Version



Horova, M. (2021). Characterization of novel SigA4-dependent WhiB-like transcription factors in Mycobacteria. (Unpublished Master thesis). The University of Nebraska-Lincoln.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Biochemistry, Under the Supervision of Professor Limei Zhang. Lincoln, Nebraska: August 2021

Copyright © 2021 Magdaléna Horová


White B-like proteins (Wbl) are iron-sulfur ([4Fe–4S]) cluster-containing transcription factors found across Actinobacteria. Seven Wbl proteins (WhiB1-7) are found in Mycobacterium tuberculosis (Mtb), a notorious pathogenic bacterium. Wbl proteins play diverse roles that enable Mtb to survive various stresses and they are also involved in virulence. However, how these transcriptions factors regulate gene transcription remains not well understood. Several Wbl proteins have been previously reported to interact with σA, the primary sigma factor of the σ70 family in mycobacteria responsible for transcription of housekeeping genes. Here we use structural analysis, site-directed mutagenesis and in vitro pull-down assays to characterize the interaction between σA and the Wbl proteins.

Our results suggest that all the previously identified σA-bound Wbl proteins tested in this study bind to the same site in σA. Moreover, the conserved aromatic residues within the [4Fe–4S] binding pocket of the Wbl proteins are important for the interaction between the Wbl proteins and σA. This information offers new insight into the mechanism of the Wbl proteins in the σA-dependent transcriptional regulation in Mtb.

Advisor: Limei Zhang