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Novel Inhibitors of DksA Effective Against Gram-Negative Bacteria

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NJH ID: #18-03

Gram-negative bacteria cause many types of infections and spread to humans in a variety of ways, producing foodborne and waterborne diseases, respiratory infections such as certain types of pneumonias, sexually transmitted diseases, or infections transmitted to people through the bite of infected insects or handling infected animals. Certain types of Gram-negative bacteria have become increasingly resistant to available antibiotics. Some strains are now resistant to all available treatments, resulting in hard to treat infections and even death, which contributes to escalating healthcare costs. Treating Gram-negative bacterial infections can be difficult because of several unique features of these bacteria. For example, the unique nature of their cell wall prevents uptake of many antibiotics. Infections have typically been treated with broad-spectrum antibiotics. However, even these drugs have become ineffective against some bacteria, leaving healthcare providers no choice but to use older drugs which can have toxic side effects. Researchers have found that RNA polymerase-binding transcription factor DksA is a transcription factor protein that acts by binding directly to RNA polymerase. DksA is required for negative regulation of rRNA expression and positive regulation of several amino acid biosynthesis promoters. In Salmonella and many other Gram-negative pathogens, DksA regulates expression of virulence programs that are essential to pathogenesis. DksA is highly conserved among Gram-negative bacteria, making this protein a potential target for small molecule antibiotics.


Scientists at the University of Colorado and National Jewish Health have identified novel compounds that specifically inhibit DksA-dependent transcription and exhibit potent anti-microbial activity. Drugs against DksA have antibiotic activity against multiple Gram-negative pathogens. Moreover, the newly discovered drugs act against persistent populations of intracellular bacteria and potentiate antimicrobial activity of other antibiotics.


Potential Applications
Infection treatment of gram-negative bacteria, including Klebsiella, E. coli, Proteus, Serratia, Salmonella, Yersinia, Enterobacter, Pseudomonas aeruginosa, Neisseria gonorrhoeae, Chlamydia trachomatis, Acinetobacter and Stenotrophomonas.


State of Development
The investigators have tested activity of the novel compounds in E.coli and Salmonella with very good results, and are currently testing the activity against several Gram-negative pathogens, including some multi-drug resistant organisms.



  • Vazquez-Torres A, et al. DksA–DnaJ redox interactions provide a signal for the activation of bacterial RNA polymerase, PNAS, 115(50): E11780–E11789. PMID: 30429329
  • Tapscott, T., J.S. Kim, M.A. Crawford, J. Westrich, L. Liu, J. Jones-Carson, and A. Vázquez-Torres. 2018. Guanosine tetraphosphate relieves the negative regulation of Salmonella pathogenicity island-2 gene transcription exerted by the AT-rich ssrA discriminator region. Scientific Reports. 8: 9465. PMID: 29930310
  • Crawford, M.A., T. Tapscott, L.F. Fitzsimmons, L. Liu, A.M. Reyes, S.J. Libby, M. Trujillo, F.C. Fang, R. Radi, A. Vázquez-Torres. 2016. Redox-active sensing by bacterial DksA transcription factors is determined by cysteine and zinc content. mBio. 7: e02161-15. PMID: 27094335
  • Henard, C.A., T. Tapscott, M.A. Crawford, M. Husain, P.T, Doulias, S. Porwollik, L. Liu, M. McClelland, H. Ischiropoulos, and A. Vázquez-Torres. 2014. The 4-Cysteine Zinc-Finger Motif of the RNA Polymerase Regulator DksA serves as a Thiol Switch for Sensing Oxidative and Nitrosative Stress. Mol. Microbiol. PMID: 24354846
  • Henard, C.A., & A. Vazquez-Torres. 2012. DksA-dependent resistance of Salmonella enterica Serovar Typhimurium against the Antimicrobial Activity of Inducible Nitric Oxide Synthase. Infect. Immun. 80:1373-1380. PMID: 22311927
  • Henard, C.A., T.J. Bourret, M. Song, & A. Vazquez-Torres. 2010. Control of redox balance by the stringent response regulatory protein promotes antioxidant defenses of Salmonella. J. Biol. Chem. 285: 36785-93. Epub 2010 Sep 17. PMID: 20851888


Patent Status
Patent application filed


Shaodong Dai, Ph.D., Michael Wempe, Ph.D and Andrés Vázquez-Torres, DVM, Ph.D.


Licensing Status
This technology is available for licensing.


For Further Information, Contact:
Emmanuel Hilaire, PhD
Technology Transfer Office
National Jewish Health
1400 Jackson Street, Room M206b
Denver, CO 80206
Voice: 303.398.1262