Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is responsible for huge global suffering. Mtb is highly adaptive being able to survive in a wide variety of microenvironments as well as persist for decades in the human host as a latent infection. Growing resistance to first, second and third line drugs are driving a need for new treatments. To combat drug-resistance and persistent infections, we need to develop effective compounds against non-replicating Mtb. Targeting protein secretion mechanisms essential for bacterial survival is one way to meet this need. Protein secretion is a key cellular process which underpins bacterial survival, promoting virulence and allowing Mtb to detect and respond to its environment. The signal peptidase, LepB, plays an integral role in this process and is essential for survival;however few studies have been conducted to characterize LepB activity and explore its role in different physiological states. In this application we propos to develop and/or run high-throughput screening (HTS) assays to identify chemical inhibitors of the Mtb signal peptidase, LepB. We think that by inhibiting this """"""""gatekeeper"""""""" protein, we will inhibit a large number of pathways critical for bacterial survival and persistence. We will take an innovative, target-driven, cell-based approach, as well as a traditional biochemical approach, to develop high throughput assays and screen for small molecule inhibitors of LepB. We will conduct screens and combine these with other assays to prioritize compounds. Small molecules identified from this work will be used as probes better to understand the physiology of tuberculosis, the changes in the secretome related to persistence and virulence, and as pre-therapeutic drug discovery agents. Because these early drug discovery compounds will act through a unique mechanism of action, they will likely be effective against multi-drug resistant and extremely multi-drug resistant TB. The significance of our proposal is that it has a dual outcome;regeneration of the early drug pipeline by enabling HTS and stimulation of basic biological studies by providing chemical probes.

Public Health Relevance

Mycobacterium tuberculosis is the causative agent of human tuberculosis, a devastating infectious disease, which kills nearly 2 million and infects more than 8 million people each year. There is an urgent unmet need for new therapeutic agents and an increased understanding of the disease process. We propose to develop high throughput assays to screen large compound libraries for anti-tubercular agents that work in new ways by targeting protein secretion, a key virulence mechanism.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
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Boyce, Jim P
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Infectious Disease Research Institute
United States
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Bonnett, Shilah A; Dennison, Devon; Files, Megan et al. (2018) A class of hydrazones are active against non-replicating Mycobacterium tuberculosis. PLoS One 13:e0198059
Bonnett, Shilah A; Ollinger, Juliane; Chandrasekera, Susantha et al. (2016) A Target-Based Whole Cell Screen Approach To Identify Potential Inhibitors of Mycobacterium tuberculosis Signal Peptidase. ACS Infect Dis 2:893-902
Kana, Bavesh Davandra; Karakousis, Petros C; Parish, Tanya et al. (2014) Future target-based drug discovery for tuberculosis? Tuberculosis (Edinb) 94:551-6