Transcription Regulation in Pathogenic Bacteria
Approximately one-third of the world population has been infected with Mycobacterium tuberculosis and millions die from this disease annually. The success of this pathogen lies in its ability to lay dormant for long periods of time and to resist the attempts of the immune system to eradicate it from the host. Although much is known about transcription initiation in model bacterial such as Escherichia coli, relatively little is known about the mechanisms of basal transcription in mycobacteria. For example, transcription factors that are essential in M. tuberculosis such as CarD and RbpA are not even present in the genome of E. coli. We have been studying the energetics of transcription initiation in this important pathogen to better understand the diversity of gene expression pathways in bacteria. In addition, as multi-drug resistant strains are becoming more prevalent we hope to find novel molecular strategies to interfere with the unique regulatory pathways of M. tuberculosis and treat this costly disease.
High-throughput, fluorsecent-aptamer-based measurements of steady-state transcription rates for the Mtb RNA polymerase.
Jensen D*, Ruiz Manzano*, Rector M, Tomko EJ, Record MT, Galburt EA.
(2023) NAR.
CarD and RbpA modify the kinetics of initial transcription and slow promoter escape of the Mycobacterium tuberculosis RNA polymerase.
Jensen D*, Ruiz Manzano, Rammohan J, Stallings CL, Galburt EA.
(2019) NAR.
The calculation of transcript flux ratios reveals single regulatory mechanisms capable of activation and repression.
Galburt EA.
(2018) PNAS.
DNA Repair in Mycobacterium tuberculosis
Our studies of the molecular pathways of Mtb have recently expanded to DNA repair. Specifically, we discovered that the activity of a critical DNA repair helicase, UvrD1, is regulated by redox potential. Whereas a monomer of UvrD1 can translocate on single-stranded DNA, it is unable to unwind duplex. In contrast, a disulfide bonded dimer is able to unwind multiple turns of DNA in about a second. Our future work is aimed at understanding how this regulation is enacted in bacterial cells under stress and what are the structural determinants of activation.
Structural basis for dimerization and activation of UvrD-family helicases.
Chadda A, Nguyen B, Lohman T, Galburt EA.
(2025) bioRxiv.
Mtb Ku stimulates multi-round DNA unwinding by UvrD1 monomers.
Chadda A, Jensen D, Ruiz Manzano A, Nguyen B, Lohman T, Galburt EA.
(2024) JMB.
Mycobacterium tuberculosis DNA repair helicase UvrD1 is activated by redox-dependent dimerization via a 2B domain cysteine.
Chadda A, Jensen D, Ruiz Manzano A, Nguyen B, Lohman T, Galburt EA.
(2022) PNAS.