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Hasenoehrl EJ, Wiggins TJ, Berney M. Bioenergetic Inhibitors: Antibiotic Efficacy and Mechanisms of Action in Mycobacterium tuberculosis. Front Cell Infect Microbiol 2021; 10:611683. [PMID: 33505923 PMCID: PMC7831573 DOI: 10.3389/fcimb.2020.611683] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/23/2020] [Indexed: 11/23/2022] Open
Abstract
Development of novel anti-tuberculosis combination regimens that increase efficacy and reduce treatment timelines will improve patient compliance, limit side-effects, reduce costs, and enhance cure rates. Such advancements would significantly improve the global TB burden and reduce drug resistance acquisition. Bioenergetics has received considerable attention in recent years as a fertile area for anti-tuberculosis drug discovery. Targeting the electron transport chain (ETC) and oxidative phosphorylation machinery promises not only to kill growing cells but also metabolically dormant bacilli that are inherently more drug tolerant. Over the last two decades, a broad array of drugs targeting various ETC components have been developed. Here, we provide a focused review of the current state of art of bioenergetic inhibitors of Mtb with an in-depth analysis of the metabolic and bioenergetic disruptions caused by specific target inhibition as well as their synergistic and antagonistic interactions with other drugs. This foundation is then used to explore the reigning theories on the mechanisms of antibiotic-induced cell death and we discuss how bioenergetic inhibitors in particular fail to be adequately described by these models. These discussions lead us to develop a clear roadmap for new lines of investigation to better understand the mechanisms of action of these drugs with complex mechanisms as well as how to leverage that knowledge for the development of novel, rationally-designed combination therapies to cure TB.
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Affiliation(s)
- Erik J Hasenoehrl
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Thomas J Wiggins
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Michael Berney
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, United States
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The Potential of Proteolytic Chimeras as Pharmacological Tools and Therapeutic Agents. Molecules 2020; 25:molecules25245956. [PMID: 33339292 PMCID: PMC7766482 DOI: 10.3390/molecules25245956] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/09/2020] [Accepted: 12/14/2020] [Indexed: 02/07/2023] Open
Abstract
The induction of protein degradation in a highly selective and efficient way by means of druggable molecules is known as targeted protein degradation (TPD). TPD emerged in the literature as a revolutionary idea: a heterobifunctional chimera with the capacity of creating an interaction between a protein of interest (POI) and a E3 ubiquitin ligase will induce a process of events in the POI, including ubiquitination, targeting to the proteasome, proteolysis and functional silencing, acting as a sort of degradative knockdown. With this programmed protein degradation, toxic and disease-causing proteins could be depleted from cells with potentially effective low drug doses. The proof-of-principle validation of this hypothesis in many studies has made the TPD strategy become a new attractive paradigm for the development of therapies for the treatment of multiple unmet diseases. Indeed, since the initial protacs (Proteolysis targeting chimeras) were posited in the 2000s, the TPD field has expanded extraordinarily, developing innovative chemistry and exploiting multiple degradation approaches. In this article, we review the breakthroughs and recent novel concepts in this highly active discipline.
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Butman HS, Kotzé TJ, Dowd CS, Strauss E. Vitamin in the Crosshairs: Targeting Pantothenate and Coenzyme A Biosynthesis for New Antituberculosis Agents. Front Cell Infect Microbiol 2020; 10:605662. [PMID: 33384970 PMCID: PMC7770189 DOI: 10.3389/fcimb.2020.605662] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 10/23/2020] [Indexed: 01/05/2023] Open
Abstract
Despite decades of dedicated research, there remains a dire need for new drugs against tuberculosis (TB). Current therapies are generations old and problematic. Resistance to these existing therapies results in an ever-increasing burden of patients with disease that is difficult or impossible to treat. Novel chemical entities with new mechanisms of action are therefore earnestly required. The biosynthesis of coenzyme A (CoA) has long been known to be essential in Mycobacterium tuberculosis (Mtb), the causative agent of TB. The pathway has been genetically validated by seminal studies in vitro and in vivo. In Mtb, the CoA biosynthetic pathway is comprised of nine enzymes: four to synthesize pantothenate (Pan) from l-aspartate and α-ketoisovalerate; five to synthesize CoA from Pan and pantetheine (PantSH). This review gathers literature reports on the structure/mechanism, inhibitors, and vulnerability of each enzyme in the CoA pathway. In addition to traditional inhibition of a single enzyme, the CoA pathway offers an antimetabolite strategy as a promising alternative. In this review, we provide our assessment of what appear to be the best targets, and, thus, which CoA pathway enzymes present the best opportunities for antitubercular drug discovery moving forward.
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Affiliation(s)
- Hailey S. Butman
- Department of Chemistry, George Washington University, Washington, DC, United States
| | - Timothy J. Kotzé
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
| | - Cynthia S. Dowd
- Department of Chemistry, George Washington University, Washington, DC, United States
| | - Erick Strauss
- Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa
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Fontes FL, Peters BJ, Crans DC, Crick DC. The Acid-Base Equilibrium of Pyrazinoic Acid Drives the pH Dependence of Pyrazinamide-Induced Mycobacterium tuberculosis Growth Inhibition. ACS Infect Dis 2020; 6:3004-3014. [PMID: 33078607 DOI: 10.1021/acsinfecdis.0c00507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pyrazinamide, a first-line antibiotic used against Mycobacterium tuberculosis, has been shown to act in a pH-dependent manner in vitro. Why pyrazinamide, an antitubercle prodrug discovered more than 65 years ago, exhibits this pH-dependent activity was unclear. Upon entering mycobacterial cells, pyrazinamide is deamidated to pyrazinoate by an enzymatic process and exists in an acid-base equilibrium with pyrazinoic acid. Thus, the effects of total pyrazinoic acid (pyrazinoic acid + pyrazinoate) on M. tuberculosis growth, pH homeostasis, and proton motive force over a range of pH values found in host tissues were investigated. Although M. tuberculosis was able to maintain pH homeostasis over an external pH range of 7.0 to 5.5, total pyrazinoic acid induced growth inhibition increased as culture medium pH was decreased from 7.3 to 6.4. Consistent with growth inhibition, total pyrazinoic acid increased both acidification of the bacterial cytoplasm and dissipation of membrane potential as the environmental pH decreased when added to the bacterial suspensions. The results suggest pyrazinoic acid is the active form of the drug, which acts as an uncoupler of proton motive force, likely a protonophore, providing a mechanistic explanation for the pH dependence of the drug activity.
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Affiliation(s)
- Fabio L. Fontes
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Benjamin J. Peters
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Debbie C. Crans
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Dean C. Crick
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
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Negatu DA, Gengenbacher M, Dartois V, Dick T. Indole Propionic Acid, an Unusual Antibiotic Produced by the Gut Microbiota, With Anti-inflammatory and Antioxidant Properties. Front Microbiol 2020; 11:575586. [PMID: 33193190 PMCID: PMC7652848 DOI: 10.3389/fmicb.2020.575586] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/02/2020] [Indexed: 12/18/2022] Open
Abstract
Most antibiotics are produced by soil microbes and typically interfere with macromolecular synthesis processes as their antibacterial mechanism of action. These natural products are often large and suffer from poor chemical tractability. Here, we discuss discovery, mechanism of action, and the therapeutic potentials of an unusual antibiotic, indole propionic acid (IPA). IPA is produced by the human gut microbiota. The molecule is small, chemically tractable, and targets amino acid biosynthesis. IPA is active against a broad spectrum of mycobacteria, including drug resistant Mycobacterium tuberculosis and non-tuberculous mycobacteria (NTM). Interestingly, the microbiota-produced metabolite is detectable in the serum of healthy individuals, tuberculosis (TB) patients, and several animal models. Thus, the microbiota in our gut may influence susceptibility to mycobacterial diseases. If a gut-lung microbiome axis can be demonstrated, IPA may have potential as a biomarker of disease progression, and development of microbiota-based therapies could be explored. In addition to its antimycobacterial activity, the molecule displays anti-inflammatory and antioxidant properties. This raises the possibility that IPA has therapeutic potential as both antibiotic and add-on host-directed drug for the treatment of TB in patient populations where disease morbidity and mortality is driven by excessive inflammation and tissue damage, such as TB-associated immune reconstitution inflammatory syndrome, TB-meningitis, and TB-diabetes.
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Affiliation(s)
- Dereje Abate Negatu
- Center for Innovative Drug Development and Therapeutic Trials for Africa, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia.,Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | - Martin Gengenbacher
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States.,Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, United States
| | - Véronique Dartois
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States.,Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, United States
| | - Thomas Dick
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States.,Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, United States.,Department of Microbiology and Immunology, Georgetown University, Washington, DC, United States
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Gopal P, Dick T. Targeted protein degradation in antibacterial drug discovery? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 152:10-14. [PMID: 31738980 DOI: 10.1016/j.pbiomolbio.2019.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/29/2019] [Accepted: 11/13/2019] [Indexed: 11/25/2022]
Abstract
Drug induced degradation of a target protein is a novel concept in drug discovery. Traditionally drugs modulate activity, as opposed to abundance, of their targets. Degradation inducing ligands act catalytically. Thus, one advantage of target degradation over the classical on-target mechanism is that lower drug concentration may be sufficient to cause the desired cellular effects. The first promoters of target degradation were discovered unintentionally: it turned out that some drugs 'accidently' promote degradation of their target by the cellular proteolytic machinery. Elegant methods were developed to target specific proteins of interest for degradation, thus enabling the rational discovery of degradation inducers. The application of targeted degradation has so far been limited to human cells. Recently, we discovered that an antibacterial drug, the anti-tuberculosis antibiotic pyrazinamide, functions as a promotor of degradation of its bacterial target. Increasing antimicrobial resistance makes the discovery of novel antibiotics more urgent than ever. Can rational target degradation be applied for the discovery of anti-bacterials? Here, we first discuss briefly some historic examples and then recent approaches in rational target degradation for human diseases. Then, we describe how the first anti-bacterial target degradation promoter pyrazinamide triggers removal of its target. Efforts are under way to exploit this specific mechanistic knowledge for the discovery of next generation pyrazinamide. We end with the big - and open - question whether targeted protein degradation as an approach to anti-bacterial drug discovery can be generalized, similar to what has been achieved in the area of drug discovery for human diseases.
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Affiliation(s)
- Pooja Gopal
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Thomas Dick
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA; Department of Medical Sciences, Hackensack Meridian School of Medicine at Seton Hall University, Nutley, NJ, USA.
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