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Negatu DA, Aragaw WW, Dartois V, Dick T. A pairwise approach to revitalize β-lactams for the treatment of TB. Antimicrob Agents Chemother 2024:e0003424. [PMID: 38690896 DOI: 10.1128/aac.00034-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 04/07/2024] [Indexed: 05/03/2024] Open
Abstract
The dual β-lactam approach has been successfully applied to overcome target redundancy in nontuberculous mycobacteria. Surprisingly, this approach has not been leveraged for Mycobacterium tuberculosis, despite the high conservation of peptidoglycan synthesis. Through a comprehensive screen of oral β-lactam pairs, we have discovered that cefuroxime strongly potentiates the bactericidal activity of tebipenem and sulopenem-advanced clinical candidates-and amoxicillin, at concentrations achieved clinically. β-lactam pairs thus have the potential to reduce TB treatment duration.
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Affiliation(s)
- Dereje A Negatu
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Center for Innovative Drug Development and Therapeutic Trials for Africa (CDT-Africa), Addis Ababa University, Addis Ababa, Ethiopia
| | - Wassihun Wedajo Aragaw
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
| | - Véronique Dartois
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, New Jersey, USA
| | - Thomas Dick
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, New Jersey, USA
- Department of Microbiology and Immunology, Georgetown University, Washington, DC, USA
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2
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de Munnik M, Lang PA, De Dios Anton F, Cacho M, Bates RH, Brem J, Rodríguez Miquel B, Schofield CJ. High-throughput screen with the l,d-transpeptidase Ldt Mt2 of Mycobacterium tuberculosis reveals novel classes of covalently reacting inhibitors. Chem Sci 2023; 14:7262-7278. [PMID: 37416715 PMCID: PMC10321483 DOI: 10.1039/d2sc06858c] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/29/2023] [Indexed: 07/08/2023] Open
Abstract
Disruption of bacterial cell wall biosynthesis in Mycobacterium tuberculosis is a promising target for treating tuberculosis. The l,d-transpeptidase LdtMt2, which is responsible for the formation of 3 → 3 cross-links in the cell wall peptidoglycan, has been identified as essential for M. tuberculosis virulence. We optimised a high-throughput assay for LdtMt2, and screened a targeted library of ∼10 000 electrophilic compounds. Potent inhibitor classes were identified, including established (e.g., β-lactams) and unexplored covalently reacting electrophilic groups (e.g., cyanamides). Protein-observed mass spectrometric studies reveal most classes to react covalently and irreversibly with the LdtMt2 catalytic cysteine (Cys354). Crystallographic analyses of seven representative inhibitors reveal induced fit involving a loop enclosing the LdtMt2 active site. Several of the identified compounds have a bactericidal effect on M. tuberculosis within macrophages, one with an MIC50 value of ∼1 μM. The results provide leads for the development of new covalently reaction inhibitors of LdtMt2 and other nucleophilic cysteine enzymes.
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Affiliation(s)
- Mariska de Munnik
- Chemistry Research Laboratory, Department of Chemistry, the Ineos Oxford Institute of Antimicrobial Research, University of Oxford 12 Mansfield Road Oxford OX1 3TA UK
| | - Pauline A Lang
- Chemistry Research Laboratory, Department of Chemistry, the Ineos Oxford Institute of Antimicrobial Research, University of Oxford 12 Mansfield Road Oxford OX1 3TA UK
| | - Francisco De Dios Anton
- Tres Cantos Medicines Development Campus, GlaxoSmithKline Calle Severo Ochoa 2, Tres Cantos Madrid Spain
| | - Mónica Cacho
- Tres Cantos Medicines Development Campus, GlaxoSmithKline Calle Severo Ochoa 2, Tres Cantos Madrid Spain
| | - Robert H Bates
- Tres Cantos Medicines Development Campus, GlaxoSmithKline Calle Severo Ochoa 2, Tres Cantos Madrid Spain
| | - Jürgen Brem
- Chemistry Research Laboratory, Department of Chemistry, the Ineos Oxford Institute of Antimicrobial Research, University of Oxford 12 Mansfield Road Oxford OX1 3TA UK
| | - Beatriz Rodríguez Miquel
- Tres Cantos Medicines Development Campus, GlaxoSmithKline Calle Severo Ochoa 2, Tres Cantos Madrid Spain
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry, the Ineos Oxford Institute of Antimicrobial Research, University of Oxford 12 Mansfield Road Oxford OX1 3TA UK
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3
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Silveiro C, Marques M, Olivença F, Pires D, Mortinho D, Nunes A, Pimentel M, Anes E, Catalão MJ. CRISPRi-mediated characterization of novel anti-tuberculosis targets: Mycobacterial peptidoglycan modifications promote beta-lactam resistance and intracellular survival. Front Cell Infect Microbiol 2023; 13:1089911. [PMID: 37009497 PMCID: PMC10050696 DOI: 10.3389/fcimb.2023.1089911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/03/2023] [Indexed: 03/17/2023] Open
Abstract
The lack of effective therapeutics against emerging multi-drug resistant strains of Mycobacterium tuberculosis (Mtb) prompts the identification of novel anti-tuberculosis targets. The essential nature of the peptidoglycan (PG) layer of the mycobacterial cell wall, which features several distinctive modifications, such as the N-glycolylation of muramic acid and the amidation of D-iso-glutamate, makes it a target of particular interest. To understand their role in susceptibility to beta-lactams and in the modulation of host-pathogen interactions, the genes encoding the enzymes responsible for these PG modifications (namH and murT/gatD, respectively) were silenced in the model organism Mycobacterium smegmatis using CRISPR interference (CRISPRi). Although beta-lactams are not included in TB-therapy, their combination with beta-lactamase inhibitors is a prospective strategy to treat MDR-TB. To uncover synergistic effects between the action of beta-lactams and the depletion of these PG modifications, knockdown mutants were also constructed in strains lacking the major beta-lactamase of M. smegmatis BlaS, PM965 (M. smegmatis ΔblaS1) and PM979 (M. smegmatis ΔblaS1 ΔnamH). The phenotyping assays affirmed the essentiality of the amidation of D-iso-glutamate to the survival of mycobacteria, as opposed to the N-glycolylation of muramic acid. The qRT-PCR assays confirmed the successful repression of the target genes, along with few polar effects and differential knockdown level depending on PAM strength and target site. Both PG modifications were found to contribute to beta-lactam resistance. While the amidation of D-iso-glutamate impacted cefotaxime and isoniazid resistance, the N-glycolylation of muramic acid substantially promoted resistance to the tested beta-lactams. Their simultaneous depletion provoked synergistic reductions in beta-lactam MICs. Moreover, the depletion of these PG modifications promoted a significantly faster bacilli killing by J774 macrophages. Whole-genome sequencing revealed that these PG modifications are highly conserved in a set of 172 clinical strains of Mtb, demonstrating their potential as therapeutic targets against TB. Our results support the development of new therapeutic agents targeting these distinctive mycobacterial PG modifications.
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Affiliation(s)
- Cátia Silveiro
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Mariana Marques
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Francisco Olivença
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - David Pires
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Universidade Católica Portuguesa, Católica Medical School, Centre for Interdisciplinary Research in Health, Lisbon, Portugal
| | - Diana Mortinho
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Alexandra Nunes
- Genomics and Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
- Faculty of Veterinary Medicine, Universidade Lusófona, Lisbon, Portugal
| | - Madalena Pimentel
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Elsa Anes
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Maria João Catalão
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- *Correspondence: Maria João Catalão,
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Gaglani P, Dwivedi M, Upadhyay TK, Kaushal RS, Ahmad I, Saeed M. A pro-oxidant property of vitamin C to overcome the burden of latent Mycobacterium tuberculosis infection: A cross-talk review with Fenton reaction. Front Cell Infect Microbiol 2023; 13:1152269. [PMID: 37153159 PMCID: PMC10155705 DOI: 10.3389/fcimb.2023.1152269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/17/2023] [Indexed: 05/09/2023] Open
Abstract
Tuberculosis (TB), caused by the bacillus M. tuberculosis, is one of the deadliest infectious illnesses of our day, along with HIV and malaria.Chemotherapy, the cornerstone of TB control efforts, is jeopardized by the advent of M. tuberculosis strains resistant to many, if not all, of the existing medications.Isoniazid (INH), rifampicin (RIF), pyrazinamide, and ethambutol are used to treat drug-susceptible TB for two months, followed by four months of INH and RIF, but chemotherapy with potentially harmful side effects is sometimes needed to treat multidrug-resistant (MDR) TB for up to two years. Chemotherapy might be greatly shortened by drugs that kill M. tuberculosis more quickly while simultaneously limiting the emergence of drug resistance.Regardless of their intended target, bactericidal medicines commonly kill pathogenic bacteria (gram-negative and gram-positive) by producing hydroxyl radicals via the Fenton reaction.Researchers have concentrated on vitamins with bactericidal properties to address the rising cases globally and have discovered that these vitamins are effective when given along with first-line drugs. The presence of elevated iron content, reactive oxygen species (ROS) generation, and DNA damage all contributed to VC's sterilizing action on M. tb in vitro. Moreover, it has a pleiotropic effect on a variety of biological processes such as detoxification, protein folding - chaperons, cell wall processes, information pathways, regulatory, virulence, metabolism etc.In this review report, the authors extensively discussed the effects of VC on M. tb., such as the generation of free radicals and bactericidal mechanisms with existing treatments, and their further drug development based on ROS production.
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Affiliation(s)
- Pratikkumar Gaglani
- Department of Life Sciences, Parul Institute of Applied Sciences and Biophysics and Structural Biology Laboratory, Center of Research for Development, Parul University, Vadodara, Gujarat, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University, Lucknow, Uttar Pradesh, India
| | - Tarun Kumar Upadhyay
- Department of Life Sciences, Parul Institute of Applied Sciences and Animal Cell Culture and Immunobiochemistry Lab, Center of Research for Development, Parul University, Vadodara, Gujarat, India
| | - Radhey Shyam Kaushal
- Department of Life Sciences, Parul Institute of Applied Sciences and Biophysics and Structural Biology Laboratory, Center of Research for Development, Parul University, Vadodara, Gujarat, India
- *Correspondence: Radhey Shyam Kaushal, ; Mohd Saeed,
| | - Irfan Ahmad
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Mohd Saeed
- Department of Biology, College of Sciences, University of Hail, Hail, Saudi Arabia
- *Correspondence: Radhey Shyam Kaushal, ; Mohd Saeed,
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Jambo A, Edessa D, Adem F, Gashaw T. Appropriateness of antimicrobial selection for treatment of pneumonia in selected public hospitals of Eastern Ethiopia: A cross-sectional study. SAGE Open Med 2023; 11:20503121231163792. [PMID: 37065976 PMCID: PMC10102944 DOI: 10.1177/20503121231163792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 02/27/2023] [Indexed: 04/18/2023] Open
Abstract
Objective Inappropriate antimicrobial use leads to drug resistance and poor clinical outcomes. Considering the lack of data regarding the drug use patterns in the treatment of pneumonia in selected study areas, the authors felt compelled to assess the appropriateness of antimicrobial usage in the treatment of pneumonia at Hiwot Fana Specialized Comprehensive University Hospital and Jugal Hospital from May 1 to 31, 2021. Methods A cross-sectional retrospective study was conducted using the medical cards of 693 admitted patients with pneumonia. The collected data were analyzed using SPSS version 26. Bivariable and multivariable logistic regression analyses were used to identify the factors associated with an initial inappropriate antibiotic use. A p value of 0.05 was used to determine the statistical significance of the association using an adjusted odds ratio with 95% confidence interval. Results Of the total participants, 116 (16.74%, 95% confidence interval: 14.1-19.6) of them received an initial inappropriate antimicrobial regimen. Ceftriaxone plus azithromycin was the most prescribed antimicrobial agent. Patients who were younger than 5 years (adjusted odds ratio = 1.71; 95% confidence interval: 1.00-2.94), between 6 and 14 years (adjusted odds ratio = 3.14; 95% confidence interval: 1.64-6.00), and older than 65 years (adjusted odds ratio = 2.97; 95% confidence interval: 1.07-2.66), with comorbid conditions (adjusted odds ratio = 1.74; 95% confidence interval: 1.10-2.72) and prescribed by medical interns (adjusted odds ratio = 1.80; 95% confidence interval: 1.14-2.84) were associated with an initial inappropriate antimicrobial use. Conclusion Around one out of every six patients had received initial inappropriate treatments. Adherence to the recommendation of guidelines and attention to extreme-aged groups and comorbidity may improve antimicrobial use.
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Affiliation(s)
- Abera Jambo
- Clinical Pharmacy Department, School of
Pharmacy, College of Health and Medical Sciences, Haramaya University, Harar,
Ethiopia
- Abera Jambo, Clinical Pharmacy Department,
School of Pharmacy, College of Health and Medical Sciences, Haramaya University,
Harar, Ethiopia.
| | - Dumessa Edessa
- Clinical Pharmacy Department, School of
Pharmacy, College of Health and Medical Sciences, Haramaya University, Harar,
Ethiopia
| | - Fuad Adem
- Clinical Pharmacy Department, School of
Pharmacy, College of Health and Medical Sciences, Haramaya University, Harar,
Ethiopia
| | - Tigist Gashaw
- Department of Pharmacology and
Toxicology, School of Pharmacy, College of Health and Medical Sciences, Haramaya
University, Harar, Ethiopia
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Acyldepsipeptide Analogues: A Future Generation Antibiotics for Tuberculosis Treatment. Pharmaceutics 2022; 14:pharmaceutics14091956. [PMID: 36145704 PMCID: PMC9502522 DOI: 10.3390/pharmaceutics14091956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 11/25/2022] Open
Abstract
Acyldepsipeptides (ADEPs) are a new class of emerging antimicrobial peptides (AMPs), which are currently explored for treatment of pathogenic infections, including tuberculosis (TB). These cyclic hydrophobic peptides have a unique bacterial target to the conventional anti-TB drugs, and present a therapeutic window to overcome Mycobacterium Tuberculosis (M. tb) drug resistance. ADEPs exerts their antibacterial activity on M. tb strains through activation of the protein homeostatic regulatory protease, the caseinolytic protease (ClpP1P2). ClpP1P2 is normally regulated and activated by the ClpP-ATPases to degrade misfolded and toxic peptides and/or short proteins. ADEPs bind and dysregulate all the homeostatic capabilities of ClpP1P2 while inducing non-selective proteolysis. The uncontrolled proteolysis leads to M. tb cell death within the host. ADEPs analogues that have been tested possess cytotoxicity and poor pharmacokinetic and pharmacodynamic properties. However, these can be improved by drug design techniques. Moreover, the use of nanomaterial in conjunction with ADEPs would yield effective synergistic effect. This new mode of action has potential to combat and eradicate the extensive multi-drug resistance (MDR) problem that is currently faced by the public health pertaining bacterial infections, especially TB.
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Yang S, Sui S, Qin Y, Chen H, Sha S, Liu X, Deng G, Ma Y. Protein O-mannosyltransferase Rv1002c contributes to low cell permeability, biofilm formation in vitro, and mycobacterial survival in mice. APMIS 2022; 130:181-192. [PMID: 34978741 DOI: 10.1111/apm.13204] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 12/28/2021] [Indexed: 01/05/2023]
Abstract
Mycobacterium tuberculosis (M. tuberculosis) Rv1002c encodes the protein O-mannosyltransferase (PMT), which catalyzes the transfer of mannose to serine or threonine residues of proteins. We explored the function of PMT in vitro and in vivo. Rv1002c protein was heterogeneously overexpressed in nonpathogenic Mycobacterium smegmatis (named as MS_Rv1002c). A series of trials including mass spectrometry, transmission electron microscope, biofilm formation and antibiotics susceptibility were performed to explore the function of PMT on bacterial survival in vitro. Mouse experiments were carried out to evaluate the virulence of PMT in vivo. PMT decreased the cell envelope permeability and promoted microbial biofilm formation. PMT enhanced the mycobacterial survival in vivo and inhibited the release of pro-inflammatory cytokines in serum. The function might be associated with an increased abundance of some mannoproteins in culture filtrate (CF). PMT is likely to be involved in mycobacterial survival both in vivo and in vitro due to increasing the mannoproteins abundance in CF.
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Affiliation(s)
- Shufeng Yang
- Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Shaoguang Sui
- Department of Emergency, The Second Hospital of Dalian Medical University, Dalian, China
| | - Yuanhua Qin
- Department of Parasitology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Haibo Chen
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Shanshan Sha
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Xin Liu
- Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Guoying Deng
- Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Yufang Ma
- Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China.,Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
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Penicillin Binding Proteins and β-Lactamases of Mycobacterium tuberculosis: Reexamination of the Historical Paradigm. mSphere 2022; 7:e0003922. [PMID: 35196121 PMCID: PMC8865919 DOI: 10.1128/msphere.00039-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Penicillin binding proteins (PBPs) have been extensively studied due to their importance to the physiology of bacterial cell wall peptidoglycan and as targets of the most widely used class of antibiotics, the β-lactams. The existing paradigm asserts that PBPs catalyze the final step of peptidoglycan biosynthesis, and β-lactams inhibit their activities. According to this paradigm, a distinct enzyme class, β-lactamases, exists to inactivate β-lactams. This paradigm has been the basis for how bacterial diseases are treated with β-lactams. We tested whether this historical view accurately reflects the relationship between β-lactams and the PBPs and the β-lactamase, BlaC, of Mycobacterium tuberculosis. BlaC was the major inactivator of the cephalosporin subclass of β-lactams. However, the PBPs PonA1 and PonA2 inactivated penicillins and carbapenems more effectively than BlaC. These findings demonstrate that select M. tuberculosis PBPs are effective at inactivating several β-lactams. Lesser-known PBPs, DacB, DacB1, DacB2, and Rv2864c, a putative PBP, were comparably more resistant to inhibition by all β-lactam subclasses. Additionally, Rv1730c exhibited low affinity to most β-lactams. Based on these findings, we conclude that in M. tuberculosis, BlaC is not the only source of inactivation of β-lactams. Therefore, the historical paradigm does not accurately describe the relationship between β-lactams and M. tuberculosis. IMPORTANCE M. tuberculosis, the causative agent of tuberculosis, kills more humans than any other bacterium. β-lactams are the most widely used class of antibiotics to treat bacterial infections. Unlike in the historical model that describes the relationship between β-lactams and M. tuberculosis, we find that M. tuberculosis penicillin binding proteins are able to inactivate select β-lactams with high efficiency.
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Privalsky TM, Soohoo AM, Wang J, Walsh CT, Wright GD, Gordon EM, Gray NS, Khosla C. Prospects for Antibacterial Discovery and Development. J Am Chem Soc 2021; 143:21127-21142. [PMID: 34860516 PMCID: PMC8855840 DOI: 10.1021/jacs.1c10200] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The rising prevalence of multidrug-resistant bacteria is an urgent health crisis that can only be countered through renewed investment in the discovery and development of antibiotics. There is no panacea for the antibacterial resistance crisis; instead, a multifaceted approach is called for. In this Perspective we make the case that, in the face of evolving clinical needs and enabling technologies, numerous validated antibacterial targets and associated lead molecules deserve a second look. At the same time, many worthy targets lack good leads despite harboring druggable active sites. Creative and inspired techniques buoy discovery efforts; while soil screening efforts frequently lead to antibiotic rediscovery, researchers have found success searching for new antibiotic leads by studying underexplored ecological niches or by leveraging the abundance of available data from genome mining efforts. The judicious use of "polypharmacology" (i.e., the ability of a drug to alter the activities of multiple targets) can also provide new opportunities, as can the continued search for inhibitors of resistance enzymes with the capacity to breathe new life into old antibiotics. We conclude by highlighting available pharmacoeconomic models for antibacterial discovery and development while making the case for new ones.
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Affiliation(s)
- Thomas M. Privalsky
- Department of Chemistry, Stanford University, Stanford, CA 94305, United States
| | - Alexander M. Soohoo
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | - Jinhua Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, United States,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115 United States
| | - Christopher T. Walsh
- Department of Chemistry, Stanford University, Stanford, CA 94305, United States,Stanford ChEM-H, Stanford University, Stanford, CA 94305, United States
| | - Gerard D. Wright
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Eric M. Gordon
- Stanford ChEM-H, Stanford University, Stanford, CA 94305, United States,Department of Medicine, Stanford University, Stanford, CA 94305, United States
| | - Nathanael S. Gray
- Stanford ChEM-H, Stanford University, Stanford, CA 94305, United States,Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, United States
| | - Chaitan Khosla
- Department of Chemistry, Stanford University, Stanford, CA 94305, United States,Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States,Stanford ChEM-H, Stanford University, Stanford, CA 94305, United States,Corresponding Author: Correspondence to
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10
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Borah P, Deb PK, Venugopala KN, Al-Shar'i NA, Singh V, Deka S, Srivastava A, Tiwari V, Mailavaram RP. Tuberculosis: An Update on Pathophysiology, Molecular Mechanisms of Drug Resistance, Newer Anti-TB Drugs, Treatment Regimens and Host- Directed Therapies. Curr Top Med Chem 2021; 21:547-570. [PMID: 33319660 DOI: 10.2174/1568026621999201211200447] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/16/2020] [Accepted: 11/19/2020] [Indexed: 11/22/2022]
Abstract
Human tuberculosis (TB) is primarily caused by Mycobacterium tuberculosis (Mtb) that inhabits inside and amidst immune cells of the host with adapted physiology to regulate interdependent cellular functions with intact pathogenic potential. The complexity of this disease is attributed to various factors such as the reactivation of latent TB form after prolonged persistence, disease progression specifically in immunocompromised patients, advent of multi- and extensivelydrug resistant (MDR and XDR) Mtb strains, adverse effects of tailor-made regimens, and drug-drug interactions among anti-TB drugs and anti-HIV therapies. Thus, there is a compelling demand for newer anti-TB drugs or regimens to overcome these obstacles. Considerable multifaceted transformations in the current TB methodologies and molecular interventions underpinning hostpathogen interactions and drug resistance mechanisms may assist to overcome the emerging drug resistance. Evidently, recent scientific and clinical advances have revolutionised the diagnosis, prevention, and treatment of all forms of the disease. This review sheds light on the current understanding of the pathogenesis of TB disease, molecular mechanisms of drug-resistance, progress on the development of novel or repurposed anti-TB drugs and regimens, host-directed therapies, with particular emphasis on underlying knowledge gaps and prospective for futuristic TB control programs.
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Affiliation(s)
- Pobitra Borah
- Pratiksha Institute of Pharmaceutical Sciences, Chandrapur Road, Panikhaiti, Guwahati-26, Assam, India
| | - Pran K Deb
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Philadelphia University, PO Box 1, Amman 19392, Jordan
| | - Katharigatta N Venugopala
- Department of Pharmaceutical Sciences, College of Clinical Pharmacy, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Nizar A Al-Shar'i
- Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science and Technology, P.O. Box 3030, Irbid, 22110, Jordan
| | - Vinayak Singh
- Drug Discovery and Development Centre (H3D), University of Cape Town, Rondebosch, 7701, South Africa
| | - Satyendra Deka
- Pratiksha Institute of Pharmaceutical Sciences, Chandrapur Road, Panikhaiti, Guwahati-26, Assam, India
| | - Amavya Srivastava
- Neuroscience and Pain Research Lab, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi, Uttar Pradesh, 221 005, India
| | - Vinod Tiwari
- Neuroscience and Pain Research Lab, Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi, Uttar Pradesh, 221 005, India
| | - Raghu P Mailavaram
- Department of Pharmaceutical Chemistry, Shri Vishnu College of Pharmacy, Vishnupur, Bhimavaram - 534 202, West Godavari Dist., Andhra Pradesh, India
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11
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N-Thio-β-lactams targeting L,D-transpeptidase-2, with activity against drug-resistant strains of Mycobacterium tuberculosis. Cell Chem Biol 2021; 28:1321-1332.e5. [PMID: 33826941 DOI: 10.1016/j.chembiol.2021.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/04/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022]
Abstract
Effective treatment of tuberculosis is frequently hindered by the emerging antimicrobial resistance of Mycobacterium tuberculosis. The present study evaluates monocyclic β-lactam compounds targeting the mycobacterial cell wall remodeling. Novel N-thio-β-lactams were designed, synthesized, and characterized on the L,D-transpeptidase-2, a validated target in M. tuberculosis. The candidates were evaluated in biochemical assays identifying five compounds presenting target-specific kinetic constants equal or superior to meropenem, a carbapenem currently considered for tuberculosis therapy. Mass spectrometry in line with the crystal structures of five target-ligand complexes revealed that the N-thio-β-lactams act via an unconventional mode of adduct formation, transferring the thio-residues from the lactam ring to the active-site cysteine of LdtMt2. The resulting stable adducts lead to a long-term inactivation of the target protein. Finally, the candidates were evaluated in vitro against a drug-susceptible and multidrug-resistant clinical isolates of M. tuberculosis, confirming the antimycobacterial effect of these novel compounds.
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12
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Levine SR, Beatty KE. Investigating β-Lactam Drug Targets in Mycobacterium tuberculosis Using Chemical Probes. ACS Infect Dis 2021; 7:461-470. [PMID: 33470787 DOI: 10.1021/acsinfecdis.0c00809] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tuberculosis (TB), caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb), infects 10 million people a year. An estimated 25% of humans harbor latent TB infections, an asymptomatic form of the disease. In both active and latent infections, Mtb relies on cell wall peptidoglycan for viability. In the current work, we synthesized fluorescent analogues of β-lactam antibiotics to study two classes of enzymes that maintain Mtb's peptidoglycan: penicillin-binding proteins (PBPs) and l,d-transpeptidases (LDTs). This set of activity-based probes included analogues of three classes of β-lactams: a monobactam (aztreonam-Cy5), a cephalosporin (cephalexin-Cy5), and a carbapenem (meropenem-Cy5). We used these probes to profile enzyme activity in protein gel-resolved lysates of Mtb. All three out-performed the commercial reagent Bocillin-FL, a penam. Meropenem-Cy5 was used to identify β-lactam targets by mass spectrometry, including PBPs, LDTs, and the β-lactamase BlaC. New probes were also used to compare PBP and LDT activity in two metabolic states: dormancy and active replication. We provide the first direct evidence that Mtb dynamically regulates the enzymes responsible for maintaining peptidoglycan in dormancy. Lastly, we profiled drug susceptibility in lysates and found that meropenem inhibits PBPs, LDTs, and BlaC.
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Affiliation(s)
- Samantha R. Levine
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92617, United States
| | - Kimberly E. Beatty
- Department of Pharmaceutical Sciences, University of California-Irvine, Irvine, California 92617, United States
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13
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Kumar G, Narayan R, Kapoor S. Chemical Tools for Illumination of Tuberculosis Biology, Virulence Mechanisms, and Diagnosis. J Med Chem 2020; 63:15308-15332. [PMID: 33307693 DOI: 10.1021/acs.jmedchem.0c01337] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tuberculosis (TB) remains one of the deadliest infectious diseases and begs the scientific community to up the ante for research and exploration of completely novel therapeutic avenues. Chemical biology-inspired design of tunable chemical tools has aided in clinical diagnosis, facilitated discovery of therapeutics, and begun to enable investigation of virulence mechanisms at the host-pathogen interface of Mycobacterium tuberculosis. This Perspective highlights chemical tools specific to mycobacterial proteins and the cell lipid envelope that have furnished rapid and selective diagnostic strategies and provided unprecedented insights into the function of the mycobacterial proteome and lipidome. We discuss chemical tools that have enabled elucidating otherwise intractable biological processes by leveraging the unique lipid and metabolite repertoire of mycobacterial species. Some of these probes represent exciting starting points with the potential to illuminate poorly understood aspects of mycobacterial pathogenesis, particularly the host membrane-pathogen interactions.
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Affiliation(s)
- Gautam Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Ponda 403 401, Goa, India
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
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14
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Märtson AG, Burch G, Ghimire S, Alffenaar JWC, Peloquin CA. Therapeutic drug monitoring in patients with tuberculosis and concurrent medical problems. Expert Opin Drug Metab Toxicol 2020; 17:23-39. [PMID: 33040625 DOI: 10.1080/17425255.2021.1836158] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Therapeutic drug monitoring (TDM) has been recommended for treatment optimization in tuberculosis (TB) but is only is used in certain countries e.g. USA, Germany, the Netherlands, Sweden and Tanzania. Recently, new drugs have emerged and PK studies in TB are continuing, which contributes further evidence for TDM in TB. The aim of this review is to provide an update on drugs used in TB, treatment strategies for these drugs, and TDM to support broader implementation. AREAS COVERED This review describes the different drug classes used for TB, multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), along with their pharmacokinetics, dosing strategies, TDM and sampling strategies. Moreover, the review discusses TDM for patient TB and renal or liver impairment, patients co-infected with HIV or hepatitis, and special patient populations - children and pregnant women. EXPERT OPINION TB treatment has a long history of using 'one size fits all.' This has contributed to treatment failures, treatment relapses, and the selection of drug-resistant isolates. While challenging in resource-limited circumstances, TDM offers the clinician the opportunity to individualize and optimize treatment early in treatment. This approach may help to refine treatment and thereby reduce adverse effects and poor treatment outcomes. Funding, training, and randomized controlled trials are needed to advance the use of TDM for patients with TB.
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Affiliation(s)
- Anne-Grete Märtson
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen , Groningen, The Netherlands
| | - Gena Burch
- Infectious Disease Pharmacokinetics Laboratory, College of Pharmacy and Emerging Pathogens Institute, University of Florida , Gainesville, FL, USA
| | - Samiksha Ghimire
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen , Groningen, The Netherlands
| | - Jan-Willem C Alffenaar
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, University of Groningen , Groningen, The Netherlands.,Department of Pharmacy, Westmead Hospital , Sydney, Australia.,Sydney Pharmacy School, The University of Sydney , Sydney, New South Wales, Australia.,Marie Bashir Institute of Infectious Diseases and Biosecurity, University of Sydney , Sydney, Australia
| | - Charles A Peloquin
- Infectious Disease Pharmacokinetics Laboratory, College of Pharmacy and Emerging Pathogens Institute, University of Florida , Gainesville, FL, USA
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15
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Tsakou F, Jersie-Christensen R, Jenssen H, Mojsoska B. The Role of Proteomics in Bacterial Response to Antibiotics. Pharmaceuticals (Basel) 2020; 13:E214. [PMID: 32867221 PMCID: PMC7559545 DOI: 10.3390/ph13090214] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 02/07/2023] Open
Abstract
For many years, we have tried to use antibiotics to eliminate the persistence of pathogenic bacteria. However, these infectious agents can recover from antibiotic challenges through various mechanisms, including drug resistance and antibiotic tolerance, and continue to pose a global threat to human health. To design more efficient treatments against bacterial infections, detailed knowledge about the bacterial response to the commonly used antibiotics is required. Proteomics is a well-suited and powerful tool to study molecular response to antimicrobial compounds. Bacterial response profiling from system-level investigations could increase our understanding of bacterial adaptation, the mechanisms behind antibiotic resistance and tolerance development. In this review, we aim to provide an overview of bacterial response to the most common antibiotics with a focus on the identification of dynamic proteome responses, and through published studies, to elucidate the formation mechanism of resistant and tolerant bacterial phenotypes.
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Affiliation(s)
| | | | | | - Biljana Mojsoska
- Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark; (F.T.); (R.J.-C.); (H.J.)
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16
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Abstract
Tuberculosis (TB) is one of the oldest health problems in the world and it remains unresolved. Multidrug-resistant-TB and extensively resistant-TB are a serious problem for control programs. The evaluation of available antibiotics has gained importance in recent years for the treatment of resistant TB. Beta-lactam antibiotics inhibit cell wall biosynthesis in the bacteria; the presence of beta-lactamase enzyme in TB bacilli raises the question of whether this group of antibiotics can be used in treatment. As a result, it has been reported that the combination of beta-lactam antibiotics with beta-lactamase is effective against Mycobacterium tuberculosis both in vitro and in vivo. The aim of this article is to review and discuss up-to-date knowledge and future perspective on beta-lactam antibiotics and TB.
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Affiliation(s)
- Mehmet Akif Gun
- Department of Medical Microbiology, Medical School, Ondokuz Mayis University, Samsun 55139, Turkey
| | - Bulent Bozdogan
- Recombinant DNA and Recombinant Protein Research Center (REDPROM), Aydin Adnan Menderes University, Aydin 09010, Turkey
| | - Ahmet Yilmaz Coban
- Tuberculosis Research Center, Akdeniz University, Antalya 07070, Turkey.,Department of Nutrition & Dietetics, Faculty of Health Sciences, Akdeniz University, Antalya 07070, Turkey
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17
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Fluorescent probes for investigating peptidoglycan biosynthesis in mycobacteria. Curr Opin Chem Biol 2020; 57:50-57. [DOI: 10.1016/j.cbpa.2020.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/31/2020] [Accepted: 04/08/2020] [Indexed: 02/02/2023]
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18
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Lopez Quezada L, Smith R, Lupoli TJ, Edoo Z, Li X, Gold B, Roberts J, Ling Y, Park SW, Nguyen Q, Schoenen FJ, Li K, Hugonnet JE, Arthur M, Sacchettini JC, Nathan C, Aubé J. Activity-Based Protein Profiling Reveals That Cephalosporins Selectively Active on Non-replicating Mycobacterium tuberculosis Bind Multiple Protein Families and Spare Peptidoglycan Transpeptidases. Front Microbiol 2020; 11:1248. [PMID: 32655524 PMCID: PMC7324553 DOI: 10.3389/fmicb.2020.01248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 05/15/2020] [Indexed: 11/13/2022] Open
Abstract
As β-lactams are reconsidered for the treatment of tuberculosis (TB), their targets are assumed to be peptidoglycan transpeptidases, as verified by adduct formation and kinetic inhibition of Mycobacterium tuberculosis (Mtb) transpeptidases by carbapenems active against replicating Mtb. Here, we investigated the targets of recently described cephalosporins that are selectively active against non-replicating (NR) Mtb. NR-active cephalosporins failed to inhibit recombinant Mtb transpeptidases. Accordingly, we used alkyne analogs of NR-active cephalosporins to pull down potential targets through unbiased activity-based protein profiling and identified over 30 protein binders. None was a transpeptidase. Several of the target candidates are plausibly related to Mtb's survival in an NR state. However, biochemical tests and studies of loss of function mutants did not identify a unique target that accounts for the bactericidal activity of these beta-lactams against NR Mtb. Instead, NR-active cephalosporins appear to kill Mtb by collective action on multiple targets. These results highlight the ability of these β-lactams to target diverse classes of proteins.
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Affiliation(s)
- Landys Lopez Quezada
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Robert Smith
- Chemical Methodologies & Library Development Center, The University of Kansas, Lawrence, KS, United States
| | - Tania J. Lupoli
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Zainab Edoo
- Sorbonne Université, Sorbonne Paris Cité, Université de Paris, INSERM, Centre de Recherche des Cordeliers, CRC, Paris, France
| | - Xiaojun Li
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Ben Gold
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Julia Roberts
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Yan Ling
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Sae Woong Park
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Quyen Nguyen
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Frank J. Schoenen
- Chemical Methodologies & Library Development Center, The University of Kansas, Lawrence, KS, United States
| | - Kelin Li
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jean-Emmanuel Hugonnet
- Sorbonne Université, Sorbonne Paris Cité, Université de Paris, INSERM, Centre de Recherche des Cordeliers, CRC, Paris, France
| | - Michel Arthur
- Sorbonne Université, Sorbonne Paris Cité, Université de Paris, INSERM, Centre de Recherche des Cordeliers, CRC, Paris, France
| | - James C. Sacchettini
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Carl Nathan
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, United States
| | - Jeffrey Aubé
- Chemical Methodologies & Library Development Center, The University of Kansas, Lawrence, KS, United States
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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19
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Xiao S, Guo H, Weiner WS, Maddox C, Mao C, Gunosewoyo H, Pelly S, White EL, Rasmussen L, Schoenen FJ, Aubé J, Bishai WR, Lun S. Revisiting the β-Lactams for Tuberculosis Therapy with a Compound-Compound Synthetic Lethality Approach. Antimicrob Agents Chemother 2019; 63:e01319-19. [PMID: 31427291 PMCID: PMC6811440 DOI: 10.1128/aac.01319-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/09/2019] [Indexed: 02/06/2023] Open
Abstract
The suboptimal effectiveness of β-lactam antibiotics against Mycobacterium tuberculosis has hindered the utility of this compound class for tuberculosis treatment. However, the results of treatment with a second-line regimen containing meropenem plus a β-lactamase inhibitor were found to be encouraging in a case study of extensively drug-resistant tuberculosis (M. C. Payen, S. De Wit, C. Martin, R. Sergysels, et al., Int J Tuberc Lung Dis 16:558-560, 2012, https://doi.org/10.5588/ijtld.11.0414). We hypothesized that the innate resistance of M. tuberculosis to β-lactams is mediated in part by noncanonical accessory proteins that are not considered the classic targets of β-lactams and that small-molecule inhibitors of those accessory targets might sensitize M. tuberculosis to β-lactams. In this study, we screened an NIH small-molecule library for the ability to sensitize M. tuberculosis to meropenem. We identified six hit compounds, belonging to either the N-arylindole or benzothiophene chemotype. Verification studies confirmed the synthetic lethality phenotype for three of the N-arylindoles and one benzothiophene derivative. The latter was demonstrated to be partially bioavailable via oral administration in mice. Structure-activity relationship studies of both structural classes identified analogs with potent antitubercular activity, alone or in combination with meropenem. Transcriptional profiling revealed that oxidoreductases, MmpL family proteins, and a 27-kDa benzoquinone methyltransferase could be the targets of the N-arylindole potentiator. In conclusion, our compound-compound synthetic lethality screening revealed novel small molecules that were capable of potentiating the action of meropenem, presumably via inhibition of the innate resistance conferred by β-lactam accessory proteins. β-Lactam compound-compound synthetic lethality may be an alternative approach for drug-resistant tuberculosis.
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Affiliation(s)
- Shiqi Xiao
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Haidan Guo
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Warren S Weiner
- Specialized Chemistry Center, University of Kansas, Lawrence, Kansas, USA
| | - Clinton Maddox
- Southern Research Molecular Libraries Screening Center, Southern Research Institute, Birmingham, Alabama, USA
| | - Chunhong Mao
- Biocomplexity Institute and Initiative, University of Virginia, Charlottesville, Virginia, USA
| | - Hendra Gunosewoyo
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Shaaretha Pelly
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - E Lucile White
- Southern Research Molecular Libraries Screening Center, Southern Research Institute, Birmingham, Alabama, USA
| | - Lynn Rasmussen
- Southern Research Molecular Libraries Screening Center, Southern Research Institute, Birmingham, Alabama, USA
| | - Frank J Schoenen
- Specialized Chemistry Center, University of Kansas, Lawrence, Kansas, USA
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - Jeffrey Aubé
- Specialized Chemistry Center, University of Kansas, Lawrence, Kansas, USA
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - William R Bishai
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shichun Lun
- Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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20
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Abstract
Tuberculosis (TB) is a major issue in global health and affects millions of people each year. Multidrug-resistant tuberculosis (MDR-TB) annually causes many deaths worldwide. Development of a way to diagnose and treat patients with MDR-TB can potentially reduce the incidence of the disease. The current study reviews the risk factors, pattern of progression, mechanism of resistance, and interaction between bacteria and the host immune system, which disrupts the immune response. It also targets the components of Mycobacterium tuberculosis (Mtb) and diagnosis and treatment options that could be available for clinical use in the near future. Mutations play an important role in development of MDR-TB and the selection of appropriate mutations can help to understand the type of resistance in patients to anti-TB drugs. In this way, they can be initially treated with proper and effective therapeutic choices, which can accelerate the course of treatment and improve patient health. Targeting the components and enzymes of Mtb is necessary for understanding bacterial survival and finding a way to destroy the pathogen and allow patients to recover faster and prevent the spread of disease, especially resistant strains.
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Affiliation(s)
- Majid Faridgohar
- Infectious Diseases Research Center, Kashan University of Medical Sciences, Kashan, Iran.,Department of Microbiology and Immunology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran
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21
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Briffotaux J, Liu S, Gicquel B. Genome-Wide Transcriptional Responses of Mycobacterium to Antibiotics. Front Microbiol 2019; 10:249. [PMID: 30842759 PMCID: PMC6391361 DOI: 10.3389/fmicb.2019.00249] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 01/30/2019] [Indexed: 11/13/2022] Open
Abstract
Antibiotics can stimulate or depress gene expression in bacteria. The analysis of transcriptional responses of Mycobacterium to antimycobacterial compounds has improved our understanding of the mode of action of various drug classes and the efficacy and effect of such compounds on the global metabolism of Mycobacterium. This approach can provide new insights for known antibiotics, for example those currently used for tuberculosis treatment, as well as help to identify the mode of action and predict the targets of new compounds identified by whole-cell screening assays. In addition, changes in gene expression profiles after antimycobacterial treatment can provide information about the adaptive ability of bacteria to escape the effects of antibiotics and allow monitoring of the physiology of the bacteria during treatment. Genome-wide expression profiling also makes it possible to pinpoint genes differentially expressed between drug sensitive Mycobacterium and multidrug-resistant clinical isolates. Finally, genes involved in adaptive responses and drug tolerance could become new targets for improving the efficacy of existing antibiotics.
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Affiliation(s)
- Julien Briffotaux
- Department of Tuberculosis Control and Prevention, Shenzhen Nanshan Center for Chronic Disease Control, Shenzhen, China.,Emerging Bacterial Pathogens Unit, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Shengyuan Liu
- Department of Tuberculosis Control and Prevention, Shenzhen Nanshan Center for Chronic Disease Control, Shenzhen, China
| | - Brigitte Gicquel
- Department of Tuberculosis Control and Prevention, Shenzhen Nanshan Center for Chronic Disease Control, Shenzhen, China.,Emerging Bacterial Pathogens Unit, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.,Mycobacterial Genetics Unit, Institut Pasteur, Paris, France
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22
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Catalão MJ, Filipe SR, Pimentel M. Revisiting Anti-tuberculosis Therapeutic Strategies That Target the Peptidoglycan Structure and Synthesis. Front Microbiol 2019; 10:190. [PMID: 30804921 PMCID: PMC6378297 DOI: 10.3389/fmicb.2019.00190] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/23/2019] [Indexed: 12/27/2022] Open
Abstract
Tuberculosis (TB), which is caused by Mycobacterium tuberculosis (Mtb), is one of the leading cause of death by an infectious diseases. The biosynthesis of the mycobacterial cell wall (CW) is an area of increasing research significance, as numerous antibiotics used to treat TB target biosynthesis pathways of essential CW components. The main feature of the mycobacterial cell envelope is an intricate structure, the mycolyl-arabinogalactan-peptidoglycan (mAGP) complex responsible for its innate resistance to many commonly used antibiotics and involved in virulence. A hallmark of mAGP is its unusual peptidoglycan (PG) layer, which has subtleties that play a key role in virulence by enabling pathogenic species to survive inside the host and resist antibiotic pressure. This dynamic and essential structure is not a target of currently used therapeutics as Mtb is considered naturally resistant to most β-lactam antibiotics due to a highly active β-lactamase (BlaC) that efficiently hydrolyses many β-lactam drugs to render them ineffective. The emergence of multidrug- and extensive drug-resistant strains to the available antibiotics has become a serious health threat, places an immense burden on health care systems, and poses particular therapeutic challenges. Therefore, it is crucial to explore additional Mtb vulnerabilities that can be used to combat TB. Remodeling PG enzymes that catalyze biosynthesis and recycling of the PG are essential to the viability of Mtb and are therefore attractive targets for novel antibiotics research. This article reviews PG as an alternative antibiotic target for TB treatment, how Mtb has developed resistance to currently available antibiotics directed to PG biosynthesis, and the potential of targeting this essential structure to tackle TB by attacking alternative enzymatic activities involved in Mtb PG modifications and metabolism.
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Affiliation(s)
- Maria João Catalão
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
| | - Sérgio R. Filipe
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Caparica, Portugal
- Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Madalena Pimentel
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
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23
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Salih EYA, Julkunen-Tiitto R, Lampi AM, Kanninen M, Luukkanen O, Sipi M, Lehtonen M, Vuorela H, Fyhrquist P. Terminalia laxiflora and Terminalia brownii contain a broad spectrum of antimycobacterial compounds including ellagitannins, ellagic acid derivatives, triterpenes, fatty acids and fatty alcohols. JOURNAL OF ETHNOPHARMACOLOGY 2018; 227:82-96. [PMID: 29733942 DOI: 10.1016/j.jep.2018.04.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 12/07/2017] [Accepted: 04/21/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Terminalia laxiflora Engl. & Diels, (Sudanese Arabic name: Darout الدروت) and Terminalia brownii Fresen (Sudanese Arabic name: Alshaf ألشاف) (Combretaceae) are used in Sudanese traditional folk medicine and in other African countries for treatment of infectious diseases, TB and its symptoms, such as cough, bronchitis and chest pain. AIM OF STUDY Because of the frequent use of T. laxiflora and T. brownii in African traditional medicine and due to the absence of studies regarding their antimycobacterial potential there was a need to screen extracts of T. laxiflora and T. brownii for their growth inhibitory potential and to study the chemical composition and compounds in growth inhibitory extracts. MATERIALS AND METHODS The plant species were collected in Sudan (Blue Nile Forest, Ed Damazin Forestry areas) and selected according to their uses in traditional medicine for the treatment of bacterial infections, including TB. Eighty extracts and fractions of the stem bark, stem wood, roots, leaves and fruits of T. laxiflora and T. brownii and nine pure compounds present in the active extracts were screened against Mycobacterium smegmatis ATCC 14468 using agar diffusion and microplate dilution methods. Inhibition zones and MIC values were estimated and compared to rifampicin. HPLC-UV/DAD, GC/MS and UHPLC/Q-TOF MS were employed to identify the compounds in the growth inhibitory extracts. RESULTS The roots of T. laxiflora and T. brownii gave the best antimycobacterial effects (IZ 22-27 mm) against Mycobacterium smegmatis. The lowest MIC of 625 µg/ml was observed for an acetone extract of the root of T. laxiflora followed by methanol and ethyl acetate extracts, both giving MIC values of 1250 µg/ml. Sephadex LH-20 column chromatography purification of T. brownii roots resulted in low MIC values of 62.5 µg/ml and 125 µg/ml for acetone and ethanol fractions, respectively, compared to 5000 µg/ml for the crude methanol extract. Methyl (S)-flavogallonate is suggested to be the main active compound in the Sephadex LH- 20 acetone fraction, while ellagic acid xyloside and methyl ellagic acid xyloside are suggested to give good antimycobacterial activity in the Sephadex LH-20 ethanol fraction. RP-18 TLC purifications of an ethyl acetate extract of T. laxiflora roots resulted in the enrichment of punicalagin in one of the fractions (Fr5). This fraction gave a five times smaller MIC (500 µg/ml) than the crude ethyl acetate extract (2500 µg/ml) and this improved activity is suggested to be mostly due to punicalagin. 1,18-octadec-9-ene-dioate, stigmast-4-en-3-one, 5α-stigmastan-3,6-dione, triacontanol, sitostenone and β-sitosterol were found in antimycobacterial hexane extracts of the stem bark of both studied species. Of these compounds, 1,18-octadec-9-ene-dioate, stigmast-4-en-3-one, 5α-stigmastan-3,6-dione, triacontanol, sitostenone have not been previously identified in T. brownii and T. laxiflora. Moreover, both plant species contained friedelin, betulinic acid, β-amyrine and two unknown oleanane-type triterpenoids. Of the listed compounds, friedelin, triacontanol and sitostenone gave a MIC of 250 µg/ml against M. smegmatis, whereas stigmasterol and β-sitosterol gave MIC values of 500 µg/ml. CONCLUSIONS Our results show that T. laxiflora and T. brownii contain antimycobacterial compounds of diverse polarities and support the traditional uses of various parts of T. laxiflora and T.brownii as decoctions for treatment of tuberculosis. Further investigations are warranted to explore additional (new) antimycobacterial compounds in the active extracts of T. laxiflora and T. brownii.
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Affiliation(s)
- Enass Y A Salih
- Faculty of Agriculture and Forestry, Department of Forest Sciences, Viikki Tropical Resources Institute, University of Helsinki, P.O. Box 27, FIN-00014, Finland; Faculty of Pharmacy, Division of Pharmaceutical Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, FIN-00014, Finland.
| | - Riitta Julkunen-Tiitto
- Faculty of Science and Forestry, Department of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, Finland
| | - Anna-Maija Lampi
- Faculty of Agriculture and Forestry, Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, Latokartanonkaari 11, FI-00014 Helsinki, Finland
| | - Markku Kanninen
- Faculty of Agriculture and Forestry, Department of Forest Sciences, Viikki Tropical Resources Institute, University of Helsinki, P.O. Box 27, FIN-00014, Finland
| | - Olavi Luukkanen
- Faculty of Agriculture and Forestry, Department of Forest Sciences, Viikki Tropical Resources Institute, University of Helsinki, P.O. Box 27, FIN-00014, Finland
| | - Marketta Sipi
- Faculty of Agriculture and Forestry, Department of Forest Sciences, Viikki Tropical Resources Institute, University of Helsinki, P.O. Box 27, FIN-00014, Finland
| | - Mari Lehtonen
- Faculty of Agriculture and Forestry, Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 27, Latokartanonkaari 11, FI-00014 Helsinki, Finland
| | - Heikki Vuorela
- Faculty of Pharmacy, Division of Pharmaceutical Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, FIN-00014, Finland
| | - Pia Fyhrquist
- Faculty of Pharmacy, Division of Pharmaceutical Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, FIN-00014, Finland.
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24
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Wlodarchak N, Teachout N, Beczkiewicz J, Procknow R, Schaenzer AJ, Satyshur K, Pavelka M, Zuercher W, Drewry D, Sauer JD, Striker R. In Silico Screen and Structural Analysis Identifies Bacterial Kinase Inhibitors which Act with β-Lactams To Inhibit Mycobacterial Growth. Mol Pharm 2018; 15:5410-5426. [PMID: 30285456 PMCID: PMC6648700 DOI: 10.1021/acs.molpharmaceut.8b00905] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
New tools and concepts are needed to combat antimicrobial resistance. Actinomycetes and firmicutes share several eukaryotic-like Ser/Thr kinases (eSTK) that offer antibiotic development opportunities, including PknB, an essential mycobacterial eSTK. Despite successful development of potent biochemical PknB inhibitors by many groups, clinically useful microbiologic activity has been elusive. Additionally, PknB kinetics are not fully described, nor are structures with specific inhibitors available to inform inhibitor design. We used computational modeling with available structural information to identify human kinase inhibitors predicted to bind PknB, and we selected hits based on drug-like characteristics intended to increase the likelihood of cell entry. The computational model suggested a family of inhibitors, the imidazopyridine aminofurazans (IPAs), bind PknB with high affinity. We performed an in-depth characterization of PknB and found that these inhibitors biochemically inhibit PknB, with potency roughly following the predicted models. A novel X-ray structure confirmed that the inhibitors bound as predicted and made favorable protein contacts with the target. These inhibitors also have antimicrobial activity toward mycobacteria and nocardia. We demonstrated that the inhibitors are uniquely potentiated by β-lactams but not antibiotics traditionally used to treat mycobacteria, consistent with PknB's role in sensing cell wall stress. This is the first demonstration in the phylum actinobacteria that some β-lactam antibiotics could be more effective if paired with a PknB inhibitor. Collectively, our data show that in silico modeling can be used as a tool to discover promising drug leads, and the inhibitors we discovered can act with clinically relevant antibiotics to restore their efficacy against bacteria with limited treatment options.
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Affiliation(s)
- Nathan Wlodarchak
- Department of Medicine, University of Wisconsin-Madison, 3341 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Nathan Teachout
- Department of Medicine, University of Wisconsin-Madison, 3341 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Jeffrey Beczkiewicz
- Department of Medicine, University of Wisconsin-Madison, 3341 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Rebecca Procknow
- Department of Medicine, University of Wisconsin-Madison, 3341 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Adam J. Schaenzer
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 4203 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Kenneth Satyshur
- Small Molecule Screening Facility, Carbone Cancer Center, University of Wisconsin-Madison, 1111Highland Ave., Madison, WI 53705
| | - Martin Pavelka
- School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14620
| | - William Zuercher
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, SGC Center for Chemical Biology, 120 Mason Farm Rd., Chapel Hill, NC 27599
| | - David Drewry
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, SGC Center for Chemical Biology, 120 Mason Farm Rd., Chapel Hill, NC 27599
| | - John-Demian Sauer
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, 4203 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706
| | - Rob Striker
- Department of Medicine, University of Wisconsin-Madison, 3341 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706,William S. Middleton Memorial Veterans Hospital, 2500 Overlook Terr., Madison, WI 53705,To whom correspondence should be addressed Rob Striker, Department of Medicine, University of Wisconsin-Madison, 3301 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706, 608-263-2994,
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25
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Smith PW, Zuccotto F, Bates RH, Martinez-Martinez MS, Read KD, Peet C, Epemolu O. Pharmacokinetics of β-Lactam Antibiotics: Clues from the Past To Help Discover Long-Acting Oral Drugs in the Future. ACS Infect Dis 2018; 4:1439-1447. [PMID: 30141902 PMCID: PMC6189874 DOI: 10.1021/acsinfecdis.8b00160] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Indexed: 01/03/2023]
Abstract
β-Lactams represent perhaps the most important class of antibiotics yet discovered. However, despite many years of active research, none of the currently approved drugs in this class combine oral activity with long duration of action. Recent developments suggest that new β-lactam antibiotics with such a profile would have utility in the treatment of tuberculosis. Consequently, the historical β-lactam pharmacokinetic data have been compiled and analyzed to identify possible directions and drug discovery strategies aimed toward new β-lactam antibiotics with this profile.
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Affiliation(s)
| | - Fabio Zuccotto
- Drug
Discovery Unit, Wellcome Centre for Anti-Infectives Research, School
of Life Sciences, University of Dundee, Dow Street, Dundee. DDI 5EH, U.K.
| | - Robert H. Bates
- Global
Health R&D, GlaxoSmithKline, Calle Severo Ochoa 2, 28760 Tres Cantos, Madrid, Spain
| | | | - Kevin D. Read
- Drug
Discovery Unit, Wellcome Centre for Anti-Infectives Research, School
of Life Sciences, University of Dundee, Dow Street, Dundee. DDI 5EH, U.K.
| | - Caroline Peet
- Drug
Discovery Unit, Wellcome Centre for Anti-Infectives Research, School
of Life Sciences, University of Dundee, Dow Street, Dundee. DDI 5EH, U.K.
| | - Ola Epemolu
- Drug
Discovery Unit, Wellcome Centre for Anti-Infectives Research, School
of Life Sciences, University of Dundee, Dow Street, Dundee. DDI 5EH, U.K.
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26
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Luthra S, Rominski A, Sander P. The Role of Antibiotic-Target-Modifying and Antibiotic-Modifying Enzymes in Mycobacterium abscessus Drug Resistance. Front Microbiol 2018; 9:2179. [PMID: 30258428 PMCID: PMC6143652 DOI: 10.3389/fmicb.2018.02179] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 08/24/2018] [Indexed: 11/21/2022] Open
Abstract
The incidence and prevalence of non-tuberculous mycobacterial (NTM) infections have been increasing worldwide and lately led to an emerging public health problem. Among rapidly growing NTM, Mycobacterium abscessus is the most pathogenic and drug resistant opportunistic germ, responsible for disease manifestations ranging from “curable” skin infections to only “manageable” pulmonary disease. Challenges in M. abscessus treatment stem from the bacteria’s high-level innate resistance and comprise long, costly and non-standardized administration of antimicrobial agents, poor treatment outcomes often related to adverse effects and drug toxicities, and high relapse rates. Drug resistance in M. abscessus is conferred by an assortment of mechanisms. Clinically acquired drug resistance is normally conferred by mutations in the target genes. Intrinsic resistance is attributed to low permeability of M. abscessus cell envelope as well as to (multi)drug export systems. However, expression of numerous enzymes by M. abscessus, which can modify either the drug-target or the drug itself, is the key factor for the pathogen’s phenomenal resistance to most classes of antibiotics used for treatment of other moderate to severe infectious diseases, like macrolides, aminoglycosides, rifamycins, β-lactams and tetracyclines. In 2009, when M. abscessus genome sequence became available, several research groups worldwide started studying M. abscessus antibiotic resistance mechanisms. At first, lack of tools for M. abscessus genetic manipulation severely delayed research endeavors. Nevertheless, the last 5 years, significant progress has been made towards the development of conditional expression and homologous recombination systems for M. abscessus. As a result of recent research efforts, an erythromycin ribosome methyltransferase, two aminoglycoside acetyltransferases, an aminoglycoside phosphotransferase, a rifamycin ADP-ribosyltransferase, a β-lactamase and a monooxygenase were identified to frame the complex and multifaceted intrinsic resistome of M. abscessus, which clearly contributes to complications in treatment of this highly resistant pathogen. Better knowledge of the underlying mechanisms of drug resistance in M. abscessus could improve selection of more effective chemotherapeutic regimen and promote development of novel antimicrobials which can overwhelm the existing resistance mechanisms. This article reviews the currently elucidated molecular mechanisms of antibiotic resistance in M. abscessus, with a focus on its drug-target-modifying and drug-modifying enzymes.
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Affiliation(s)
- Sakshi Luthra
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Anna Rominski
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Peter Sander
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.,National Center for Mycobacteria, Zurich, Switzerland
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27
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Ealand CS, Machowski EE, Kana BD. β-lactam resistance: The role of low molecular weight penicillin binding proteins, β-lactamases and ld-transpeptidases in bacteria associated with respiratory tract infections. IUBMB Life 2018; 70:855-868. [PMID: 29717815 DOI: 10.1002/iub.1761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/04/2018] [Indexed: 02/02/2023]
Abstract
Disruption of peptidoglycan (PG) biosynthesis in the bacterial cell wall by β-lactam antibiotics has transformed therapeutic options for bacterial infections. These antibiotics target the transpeptidase domains in penicillin binding proteins (PBPs), which can be classified into high and low molecular weight (LMW) counterparts. While the essentiality of the former has been extensively demonstrated, the physiological roles of LMW PBPs remain poorly understood. Herein, we review the function of LMW PBPs, β-lactamases and ld-transpeptidases (Ldts) in pathogens associated with respiratory tract infections. More specifically, we explore their roles in mediating β-lactam resistance. Using a comparative genomics approach, we identified a high degree of genetic redundancy for LMW PBPs which retain the motifs, SxxN, SxN and KTG required for catalytic activity. Differences in domain architecture suggest distinct physiological roles, possibly related to bacterial cell cycle and/or adaptation to various environmental conditions. Many of the LMW PBPs play an important role in β-lactam resistance either through mutation or variation in abundance. In all of the bacterial genomes assessed, at least one β-lactamase homologue is present, suggesting that enzymatic degradation of β-lactams is a highly conserved resistance mechanism. Furthermore, the presence of Ldt homologues in the majority of species surveyed suggests that alternative PG crosslinking may further mediate β-lactam drug resistance. A deeper understanding of the interplay between these different mechanisms of β-lactam resistance will provide a framework for new therapeutics, which are urgently required given the rapid emergence of antimicrobial resistance. © 2018 IUBMB Life, 70(9):855-868, 2018.
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Affiliation(s)
- Christopher S Ealand
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Edith E Machowski
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Bavesh D Kana
- DST/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa.,MRC-CAPRISA HIV-TB Pathogenesis and Treatment Research Unit, Centre for the AIDS Programme of Research in South Africa, CAPRISA, Durban, South Africa
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28
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Squeglia F, Ruggiero A, Berisio R. Chemistry of Peptidoglycan in Mycobacterium tuberculosis
Life Cycle: An off-the-wall Balance of Synthesis and Degradation. Chemistry 2017; 24:2533-2546. [DOI: 10.1002/chem.201702973] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Flavia Squeglia
- Institute of Biostructures and Bioimaging; CNR; Via Mezzocannone 16. 80134 Napoli Italy
| | - Alessia Ruggiero
- Institute of Biostructures and Bioimaging; CNR; Via Mezzocannone 16. 80134 Napoli Italy
| | - Rita Berisio
- Institute of Biostructures and Bioimaging; CNR; Via Mezzocannone 16. 80134 Napoli Italy
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29
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Cavanaugh JS, Jou R, Wu MH, Dalton T, Kurbatova E, Ershova J, Cegielski JP. Susceptibilities of MDR Mycobacterium tuberculosis isolates to unconventional drugs compared with their reported pharmacokinetic/pharmacodynamic parameters. J Antimicrob Chemother 2017; 72:1678-1687. [PMID: 28333192 DOI: 10.1093/jac/dkx022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 01/12/2017] [Indexed: 12/21/2022] Open
Abstract
Background The second-line drugs recommended to treat drug-resistant TB are toxic, expensive and difficult to procure. Given increasing resistance, the need for additional anti-TB drugs has become more urgent. But new drugs take time to develop and are expensive. Some commercially available drugs have reported anti-mycobacterial activity but are not routinely used because supporting laboratory and clinical evidence is sparse. Methods We analysed 217 MDR M. tuberculosis isolates including 153 initial isolates from unique patients and 64 isolates from follow-up specimens during the course of treatment. The resazurin microdilution assay was performed to determine MICs of trimethoprim/sulfamethoxazole, mefloquine, thioridazine, clofazimine, amoxicillin/clavulanate, meropenem/clavulanate, nitazoxanide, linezolid and oxyphenbutazone. Isoniazid was used for validation. We calculated the MIC 50 and MIC 90 as the MICs at which growth of 50% and 90% of isolates was inhibited, respectively. Results The MIC 50 s, in mg/L, for initial isolates were as follows: trimethoprim/sulfamethoxazole, 0.2/4; mefloquine, 8; thioridazine, 4; clofazimine, 0.25; amoxicillin/clavulanate, 16/8; meropenem/clavulanate, 1/2.5; nitazoxanide, 16; linezolid, 0.25; and oxyphenbutazone, 40. The MIC 90 s, in mg/L, for initial isolates were as follows: trimethoprim/sulfamethoxazole, 0.4/8; mefloquine, 8; thioridazine, 8; clofazimine, 0.5; amoxicillin/clavulanate, 32/16; meropenem/clavulanate, 8/2.5; nitazoxanide, 16; linezolid, 0.25; and oxyphenbutazone, 60. By comparison, the MIC 90 of isoniazid was >4 mg/L, as expected. There was no evidence that previous treatment affected susceptibility to any drug. Conclusions Most drugs demonstrated efficacy against M. tuberculosis . When these MICs are compared with the published pharmacokinetic/pharmacodynamic profiles of the respective drugs in humans, trimethoprim/sulfamethoxazole, meropenem/clavulanate, linezolid, clofazimine and nitazoxanide appear promising and warrant further clinical investigation.
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Affiliation(s)
- Joseph S Cavanaugh
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ruwen Jou
- Taiwan Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Mei-Hua Wu
- Taiwan Centers for Disease Control, Taipei, Taiwan, Republic of China
| | - Tracy Dalton
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Julia Ershova
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - J Peter Cegielski
- United States Centers for Disease Control and Prevention, Atlanta, GA, USA
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30
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Becker K, Haldimann K, Selchow P, Reinau LM, Dal Molin M, Sander P. Lipoprotein Glycosylation by Protein- O-Mannosyltransferase (MAB_1122c) Contributes to Low Cell Envelope Permeability and Antibiotic Resistance of Mycobacterium abscessus. Front Microbiol 2017; 8:2123. [PMID: 29163413 PMCID: PMC5673659 DOI: 10.3389/fmicb.2017.02123] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/18/2017] [Indexed: 12/12/2022] Open
Abstract
Lipoproteins are important components of the mycobacterial cell envelope due to their function in cell wall homeostasis and bacterial virulence. They are post-translationally modified with lipid- and glycosyl-residues in various species and interference with acylation or glycosylation leads to reduced growth and attenuated virulence in Mycobacterium tuberculosis. Lipoproteins are also expressed in the emerging and highly drug resistant pathogen Mycobacterium abscessus which frequently affects the lungs of patients with chronic pulmonary disease or cystic fibrosis. We investigated post-translational modification, acylation and glycosylation, of heterologously expressed (M. tuberculosis LppX and Mpt83) and endogenous (SodC) lipoproteins at the molecular level in M. abscessus and identified MAB_1122c as protein O-mannosyltransferase (Pmt). Both, heterologous and endogenous lipoproteins carried a characteristic lipid anchor with palmitic acid (C16), palmitoleic acid (C16:1), oleic acid (C18), or tuberculostearic acid (C19) modifications. Multiple hexose-moieties were detected in the N-terminal region of the model lipoproteins expressed in M. abscessus. Conservation of lipoprotein glycosylation in M. tuberculosis and M. abscessus was revealed and points toward the existence of an O-glycosylation motif or other regulatory mechanisms regarding this post-translational modification. Deletion of MAB_1122c prevented glycosylation and affected susceptibility to specific antibiotics which are large or target peptidoglycan synthesis and to lysozyme. Cell envelope permeability of M. abscessus Δpmt was increased and mutant bacteria showed reduced survival inside macrophages. The results provide a link between post-translational modification of lipoproteins and the permeability of the mycobacterial cell envelope which stresses the importance of lipoproteins as components of this complex structure.
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Affiliation(s)
- Katja Becker
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Klara Haldimann
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Petra Selchow
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Lukas M Reinau
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Michael Dal Molin
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland
| | - Peter Sander
- Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland.,National Center for Mycobacteria, Zürich, Switzerland
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31
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Bhat ZS, Rather MA, Maqbool M, Lah HU, Yousuf SK, Ahmad Z. Cell wall: A versatile fountain of drug targets in Mycobacterium tuberculosis. Biomed Pharmacother 2017; 95:1520-1534. [PMID: 28946393 DOI: 10.1016/j.biopha.2017.09.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 09/07/2017] [Accepted: 09/10/2017] [Indexed: 12/18/2022] Open
Abstract
Tuberculosis is the leading infectious disease responsible for an estimated one and a half million human deaths each year around the globe. HIV-TB coinfection and rapid increase in the emergence of drug resistant forms of TB is a dangerous scenario. This underlines the urgent need for new drugs with novel mechanism of action. A plethora of literature exist that highlight the importance of enzymes involved in the biosynthesis of mycobacterial cell wall responsible for its survival, growth, permeability, virulence and resistance to antibiotics. Therefore, assembly of cell wall components is an attractive target for the development of chemotherapeutics against Mycobacterium tuberculosis. The aim of this review is to highlight novel sets of enzyme inhibitors that disrupt its cell wall biosynthetic pathway. These include the currently approved first and second line drugs, candidates in clinical trials and current structure activity guided endeavors of scientific community to identify new potent inhibitors with least cytotoxicity and better efficacy against emergence of drug resistance till date.
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Affiliation(s)
- Zubair Shanib Bhat
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
| | - Muzafar Ahmad Rather
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Mubashir Maqbool
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Zoology, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Hafiz Ul Lah
- Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Syed Khalid Yousuf
- Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Zahoor Ahmad
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
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32
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Sadiq FA, Flint S, Li Y, Ou K, Yuan L, He GQ. Phenotypic and genetic heterogeneity within biofilms with particular emphasis on persistence and antimicrobial tolerance. Future Microbiol 2017; 12:1087-1107. [DOI: 10.2217/fmb-2017-0042] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Phenotypic changes or phase variation within biofilms is an important feature of bacterial dormant life. Enhanced resistance to antimicrobials is one of the distinct features displayed by a fraction of cells within biofilms. It is believed that persisters are mainly responsible for this phenotypic heterogeneity. However, there is still an unresolved debate on the formation of persisters. In this short review, we highlight all known genomic and proteomic changes encountered by bacterial cells within biofilms. We have also described all phenotypic changes displayed by bacterial cells within biofilms with particular emphasis on enhanced antimicrobial tolerance of biofilms with particular reference to persisters. In addition, all currently known models of persistence have been succinctly discussed.
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Affiliation(s)
- Faizan A Sadiq
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
| | - Steve Flint
- School of Food & Nutrition, Massey University, Private Bag 11 222, Palmerston North 4474, New Zealand
| | - YanJun Li
- Research Institute of Food Science, Hangzhou Wahaha Group Co, Ltd, Hangzhou 310018, China
| | - Kai Ou
- Research Institute of Food Science, Hangzhou Wahaha Group Co, Ltd, Hangzhou 310018, China
| | - Lei Yuan
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
| | - Guo Qing He
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
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33
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Buchieri MV, Cimino M, Rebollo-Ramirez S, Beauvineau C, Cascioferro A, Favre-Rochex S, Helynck O, Naud-Martin D, Larrouy-Maumus G, Munier-Lehmann H, Gicquel B. Nitazoxanide Analogs Require Nitroreduction for Antimicrobial Activity in Mycobacterium smegmatis. J Med Chem 2017; 60:7425-7433. [PMID: 28846409 DOI: 10.1021/acs.jmedchem.7b00726] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we aimed to decipher the natural resistance mechanisms of mycobacteria against novel compounds isolated by whole-cell-based high-throughput screening (HTS). We identified active compounds using Mycobacterium aurum. Further analyses were performed to determine the resistance mechanism of M. smegmatis against one hit, 3-bromo-N-(5-nitrothiazol-2-yl)-4-propoxybenzamide (3), which turned out to be an analog of the drug nitazoxanide (1). We found that the repression of the gene nfnB coding for the nitroreductase NfnB was responsible for the natural resistance of M. smegmatis against 3. The overexpression of nfnB resulted in sensitivity of M. smegmatis to 3. This compound must be metabolized into hydroxylamine intermediate for exhibiting antibacterial activity. Thus, we describe, for the first time, the activity of a mycobacterial nitroreductase against 1 analogs, highlighting the differences in the metabolism of nitro compounds among mycobacterial species and emphasizing the potential of nitro drugs as antibacterials in various bacterial species.
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Affiliation(s)
- Maria V Buchieri
- Unité de Génétique Mycobactérienne, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Mena Cimino
- Unité de Génétique Mycobactérienne, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Sonia Rebollo-Ramirez
- MRC Centre for Molecular Bacteriology & Infection, Imperial College London , London SW7 2AZ, United Kingdom
| | - Claire Beauvineau
- PSL Research University,CNRS, INSERM, Chemical Library, Institut Curie UMR9187/U1196, UMR3666/U1143 , 91405 Orsay Cedex, France
| | - Alessandro Cascioferro
- Unité de Pathogénomique Mycobactérienne Intégrée, Institut Pasteur , 75724 Paris Cedex 15, France
| | - Sandrine Favre-Rochex
- Unité de Génétique Mycobactérienne, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Olivier Helynck
- Unité de Chimie et Biocatalyse, Département de Biologie Structurale et Chimie, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Delphine Naud-Martin
- PSL Research University,CNRS, INSERM, Chemical Library, Institut Curie UMR9187/U1196, UMR3666/U1143 , 91405 Orsay Cedex, France
| | - Gerald Larrouy-Maumus
- MRC Centre for Molecular Bacteriology & Infection, Imperial College London , London SW7 2AZ, United Kingdom
| | - Hélène Munier-Lehmann
- Unité de Chimie et Biocatalyse, Département de Biologie Structurale et Chimie, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Brigitte Gicquel
- Unité de Génétique Mycobactérienne, Institut Pasteur , 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France
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34
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2-aminoimidazoles potentiate ß-lactam antimicrobial activity against Mycobacterium tuberculosis by reducing ß-lactamase secretion and increasing cell envelope permeability. PLoS One 2017; 12:e0180925. [PMID: 28749949 PMCID: PMC5547695 DOI: 10.1371/journal.pone.0180925] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 06/23/2017] [Indexed: 11/21/2022] Open
Abstract
There is an urgent need to develop new drug treatment strategies to control the global spread of drug-sensitive and multidrug-resistant Mycobacterium tuberculosis (M. tuberculosis). The ß-lactam class of antibiotics is among the safest and most widely prescribed antibiotics, but they are not effective against M. tuberculosis due to intrinsic resistance. This study shows that 2-aminoimidazole (2-AI)-based small molecules potentiate ß-lactam antibiotics against M. tuberculosis. Active 2-AI compounds significantly reduced the minimal inhibitory and bactericidal concentrations of ß-lactams by increasing M. tuberculosis cell envelope permeability and decreasing protein secretion including ß-lactamase. Metabolic labeling and transcriptional profiling experiments revealed that 2-AI compounds impair mycolic acid biosynthesis, export and linkage to the mycobacterial envelope, counteracting an important defense mechanism reducing permeability to external agents. Additionally, other important constituents of the M. tuberculosis outer membrane including sulfolipid-1 and polyacyltrehalose were also less abundant in 2-AI treated bacilli. As a consequence of 2-AI treatment, M. tuberculosis displayed increased sensitivity to SDS, increased permeability to nucleic acid staining dyes, and rapid binding of cell wall targeting antibiotics. Transcriptional profiling analysis further confirmed that 2-AI induces transcriptional regulators associated with cell envelope stress. 2-AI based small molecules potentiate the antimicrobial activity of ß-lactams by a mechanism that is distinct from specific inhibitors of ß-lactamase activity and therefore may have value as an adjunctive anti-TB treatment.
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Identification of Mycobacterial Genes Involved in Antibiotic Sensitivity: Implications for the Treatment of Tuberculosis with β-Lactam-Containing Regimens. Antimicrob Agents Chemother 2017; 61:AAC.00425-17. [PMID: 28438925 DOI: 10.1128/aac.00425-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/09/2017] [Indexed: 12/25/2022] Open
Abstract
In a Mycobacterium smegmatis mutant library screen, transposon mutants with insertions in fhaA, dprE2, rpsT, and parA displayed hypersusceptibility to antibiotics, including the β-lactams meropenem, ampicillin, amoxicillin, and cefotaxime. Sub-MIC levels of octoclothepin, a psychotic drug inhibiting ParA, phenocopied the parA insertion and enhanced the bactericidal activity of meropenem against Mycobacterium tuberculosis in combination with clavulanate. Our study identifies novel factors associated with antibiotic resistance, with implications in repurposing β-lactams for tuberculosis treatment.
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Bianchet MA, Pan YH, Basta LAB, Saavedra H, Lloyd EP, Kumar P, Mattoo R, Townsend CA, Lamichhane G. Structural insight into the inactivation of Mycobacterium tuberculosis non-classical transpeptidase Ldt Mt2 by biapenem and tebipenem. BMC BIOCHEMISTRY 2017; 18:8. [PMID: 28545389 PMCID: PMC5445500 DOI: 10.1186/s12858-017-0082-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/09/2017] [Indexed: 05/29/2023]
Abstract
Background The carbapenem subclass of β-lactams is among the most potent antibiotics available today. Emerging evidence shows that, unlike other subclasses of β-lactams, carbapenems bind to and inhibit non-classical transpeptidases (L,D-transpeptidases) that generate 3 → 3 linkages in bacterial peptidoglycan. The carbapenems biapenem and tebipenem exhibit therapeutically valuable potencies against Mycobacterium tuberculosis (Mtb). Results Here, we report the X-ray crystal structures of MtbL,D-transpeptidase-2 (LdtMt2) complexed with biapenem or tebipenem. Despite significant variations in carbapenem sulfur side chains, biapenem and tebipenem ultimately form an identical adduct that docks to the outer cavity of LdtMt2. We propose that this common adduct is an enzyme catalyzed decomposition of the carbapenem adduct by a mechanism similar to S-conjugate elimination by β-lyases. Conclusion The results presented here demonstrate biapenem and tebipenem bind to the outer cavity of LdtMt2, covalently inactivate the enzyme, and subsequently degrade via an S-conjugate elimination mechanism. We discuss structure based drug design based on the findings and propose that the S-conjugate elimination can be leveraged to design novel agents to deliver and locally release antimicrobial factors to act synergistically with the carbapenem carrier. Electronic supplementary material The online version of this article (doi:10.1186/s12858-017-0082-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mario A Bianchet
- Department of Neurology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD, 21205, USA. .,Department of Biophysics and Biophysical Chemistry, Structural Enzymology and Thermodynamics Group, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD, 21205, USA.
| | - Ying H Pan
- Department of Neurology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD, 21205, USA
| | | | - Harry Saavedra
- Department of Neurology, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Evan P Lloyd
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Pankaj Kumar
- Division of Infectious Diseases, Center for Tuberculosis Research, Taskforce to study Resistance Emergence & Antimicrobial development Technology (TREAT), Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA
| | - Rohini Mattoo
- Division of Infectious Diseases, Center for Tuberculosis Research, Taskforce to study Resistance Emergence & Antimicrobial development Technology (TREAT), Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA
| | - Craig A Townsend
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.,Division of Infectious Diseases, Taskforce to study Resistance Emergence & Antimicrobial development Technology (TREAT), Johns Hopkins University School of Medicine, 1503 E. Jefferson Street, Baltimore, MD, 21231, USA
| | - Gyanu Lamichhane
- Division of Infectious Diseases, Center for Tuberculosis Research, Taskforce to study Resistance Emergence & Antimicrobial development Technology (TREAT), Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA. .,Division of Infectious Diseases, Taskforce to study Resistance Emergence & Antimicrobial development Technology (TREAT), Johns Hopkins University School of Medicine, 1503 E. Jefferson Street, Baltimore, MD, 21231, USA.
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Nasiri MJ, Haeili M, Ghazi M, Goudarzi H, Pormohammad A, Imani Fooladi AA, Feizabadi MM. New Insights in to the Intrinsic and Acquired Drug Resistance Mechanisms in Mycobacteria. Front Microbiol 2017; 8:681. [PMID: 28487675 PMCID: PMC5403904 DOI: 10.3389/fmicb.2017.00681] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 04/04/2017] [Indexed: 01/25/2023] Open
Abstract
Infectious diseases caused by clinically important Mycobacteria continue to be an important public health problem worldwide primarily due to emergence of drug resistance crisis. In recent years, the control of tuberculosis (TB), the disease caused by Mycobacterium tuberculosis (MTB), is hampered by the emergence of multidrug resistance (MDR), defined as resistance to at least isoniazid (INH) and rifampicin (RIF), two key drugs in the treatment of the disease. Despite the availability of curative anti-TB therapy, inappropriate and inadequate treatment has allowed MTB to acquire resistance to the most important anti-TB drugs. Likewise, for most mycobacteria other than MTB, the outcome of drug treatment is poor and is likely related to the high levels of antibiotic resistance. Thus, a better knowledge of the underlying mechanisms of drug resistance in mycobacteria could aid not only to select the best therapeutic options but also to develop novel drugs that can overwhelm the existing resistance mechanisms. In this article, we review the distinctive mechanisms of antibiotic resistance in mycobacteria.
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Affiliation(s)
- Mohammad J. Nasiri
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Mehri Haeili
- Department of Biology, Faculty of Natural Sciences, University of TabrizTabriz, Iran
| | - Mona Ghazi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Hossein Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Ali Pormohammad
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Abbas A. Imani Fooladi
- Applied Microbiology Research Center, Baqiyatallah University of Medical SciencesTehran, Iran
| | - Mohammad M. Feizabadi
- Department of Microbiology, School of Medicine, Tehran University of Medical SciencesTehran, Iran
- Thoracic Research Center, Imam Khomeini Hospital, Tehran University of Medical SciencesTehran, Iran
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Nguyen TV, Blackledge MS, Lindsey EA, Minrovic BM, Ackart DF, Jeon AB, Obregón-Henao A, Melander RJ, Basaraba RJ, Melander C. The Discovery of 2-Aminobenzimidazoles That Sensitize Mycobacterium smegmatis
and M. tuberculosis
to β-Lactam Antibiotics in a Pattern Distinct from β-Lactamase Inhibitors. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201612006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- T. Vu Nguyen
- Department of Chemistry; North Carolina State University; Raleigh NC 27695 USA
| | - Meghan S. Blackledge
- Current address: Department of Chemistry; High Point University; High Point NC 27268 USA
| | - Erick A. Lindsey
- Department of Chemistry; North Carolina State University; Raleigh NC 27695 USA
| | - Bradley M. Minrovic
- Department of Chemistry; North Carolina State University; Raleigh NC 27695 USA
| | - David F. Ackart
- Department of Microbiology, Immunology, and Pathology; Colorado State University; Fort Collins CO 80523 USA
| | - Albert B. Jeon
- Department of Microbiology, Immunology, and Pathology; Colorado State University; Fort Collins CO 80523 USA
| | - Andrés Obregón-Henao
- Department of Microbiology, Immunology, and Pathology; Colorado State University; Fort Collins CO 80523 USA
| | - Roberta J. Melander
- Department of Chemistry; North Carolina State University; Raleigh NC 27695 USA
| | - Randall J. Basaraba
- Department of Microbiology, Immunology, and Pathology; Colorado State University; Fort Collins CO 80523 USA
| | - Christian Melander
- Department of Chemistry; North Carolina State University; Raleigh NC 27695 USA
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Nguyen TV, Blackledge MS, Lindsey EA, Minrovic BM, Ackart DF, Jeon AB, Obregón-Henao A, Melander RJ, Basaraba RJ, Melander C. The Discovery of 2-Aminobenzimidazoles That Sensitize Mycobacterium smegmatis and M. tuberculosis to β-Lactam Antibiotics in a Pattern Distinct from β-Lactamase Inhibitors. Angew Chem Int Ed Engl 2017; 56:3940-3944. [PMID: 28247991 DOI: 10.1002/anie.201612006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/24/2017] [Indexed: 11/09/2022]
Abstract
A library of 2-aminobenzimidazole derivatives was screened for the ability to suppress β-lactam resistance in Mycobacterium smegmatis. Several non-bactericidal compounds were identified that reversed intrinsic resistance to β-lactam antibiotics in a manner distinct from β-lactamase inhibitors. Activity also translates to M. tuberculosis, with a lead compound from this study potently suppressing carbenicillin resistance in multiple M. tuberculosis strains (including multidrug-resistant strains). Preliminary mechanistic studies revealed that the lead compounds act through a mechanism distinct from that of traditional β-lactamase inhibitors.
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Affiliation(s)
- T Vu Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Meghan S Blackledge
- Current address: Department of Chemistry, High Point University, High Point, NC, 27268, USA
| | - Erick A Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Bradley M Minrovic
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - David F Ackart
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Albert B Jeon
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Andrés Obregón-Henao
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Roberta J Melander
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Randall J Basaraba
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
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40
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Mutation in an Unannotated Protein Confers Carbapenem Resistance in Mycobacterium tuberculosis. Antimicrob Agents Chemother 2017; 61:AAC.02234-16. [PMID: 28069655 DOI: 10.1128/aac.02234-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/04/2017] [Indexed: 11/20/2022] Open
Abstract
β-Lactams are the most widely used antibacterials. Among β-lactams, carbapenems are considered the last line of defense against recalcitrant infections. As recent developments have prompted consideration of carbapenems for treatment of drug-resistant tuberculosis, it is only a matter of time before Mycobacterium tuberculosis strains resistant to these drugs will emerge. In the present study, we investigated the genetic basis that confers such resistance. To our surprise, instead of mutations in the known β-lactam targets, a single nucleotide polymorphism in the Rv2421c-Rv2422 intergenic region was common among M. tuberculosis mutants selected with meropenem or biapenem. We present data supporting the hypothesis that this locus harbors a previously unidentified gene that encodes a protein. This protein binds to β-lactams, slowly hydrolyzes the chromogenic β-lactam nitrocefin, and is inhibited by select penicillins and carbapenems and the β-lactamase inhibitor clavulanate. The mutation results in a W62R substitution that reduces the protein's nitrocefin-hydrolyzing activity and binding affinities for carbapenems.
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41
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Devi P, Rutledge PJ. Cyclobutanone Analogues of β-Lactam Antibiotics: β-Lactamase Inhibitors with Untapped Potential? Chembiochem 2017; 18:338-351. [PMID: 27992105 DOI: 10.1002/cbic.201600529] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Indexed: 11/11/2022]
Abstract
β-Lactam antibiotics have been used for many years to treat bacterial infections. However the effective treatment of an increasing range of microbial infections is threatened by bacterial resistance to β-lactams: the prolonged, widespread (and at times reckless) use of these drugs has spawned widespread resistance, which renders them ineffective against many bacterial strains. The cyclobutanone ring system is isosteric with β-lactam: in cyclobutanone analogues, the eponymous cyclic amide is replaced with an all-carbon ring, the amide N is substituted by a tertiary C-H α to a ketone. Cyclobutanone analogues of various β-lactam antibiotics have been investigated over the last 35 years, initially as prospective antibiotics in their own right and inhibitors of the β-lactamase enzymes that impart resistance to β-lactams. More recently they have been tested as inhibitors of other serine proteases and as mechanistic probes of β-lactam biosynthesis. Cyclobutanone analogues of the penam ring system are the first reversible inhibitors with moderate activity against all classes of β-lactamase; other compounds from this family inhibit Streptomyces R61 dd-carboxypeptidase/transpeptidase, human neutrophil elastase and porcine pancreatic elastase. But has their potential as enzyme inhibitors been fully exploited? Challenges in synthesising diversely functionalised cyclobutanone derivatives mean that only a limited number have been made (with limited structural diversity) and evaluated. This review surveys the different synthetic approaches that have been taken to these compounds, the investigations made to evaluate their biological activity and prospects for future developments in this area.
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Affiliation(s)
- Prarthana Devi
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Peter J Rutledge
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
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42
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Abstract
Members of the genus Mycobacterium are the most prevalent cause of infectious diseases. Mycobacteria have a complex cell envelope containing a peptidoglycan layer and an additional arabinogalactan polymer to which a mycolic acid bilayer is linked; this complex, multilayered cell wall composition (mAGP) is conserved among all CMN group bacteria. The arabinogalactan and mycolic acid synthesis pathways constitute effective drug targets for tuberculosis treatment. Ethambutol (EMB), a classical antituberculosis drug, inhibits the synthesis of the arabinose polymer. Although EMB acts bacteriostatically, its underlying molecular mechanism remains unclear. Here, we used Corynebacterium glutamicum and Mycobacterium phlei as model organisms to study the effects of EMB at the single-cell level. Our results demonstrate that EMB specifically blocks apical cell wall synthesis, but not cell division, explaining the bacteriostatic effect of EMB. Furthermore, the data suggest that members of the family Corynebacterineae have two dedicated machineries for cell elongation (elongasome) and cytokinesis (divisome). Antibiotic treatment of bacterial pathogens has contributed enormously to the increase in human health. Despite the apparent importance of antibiotic treatment of bacterial infections, surprisingly little is known about the molecular functions of antibiotic actions in the bacterial cell. Here, we analyzed the molecular effects of ethambutol, a first-line antibiotic against infections caused by members of the genus Mycobacterium. We find that this drug selectively blocks apical cell growth but still allows for effective cytokinesis. As a consequence, cells survive ethambutol treatment and adopt a pneumococcal cell growth mode with cell wall synthesis only at the site of cell division. However, combined treatment of ethambutol and beta-lactam antibiotics acts synergistically and effectively stops cell proliferation.
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43
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Liu L, Yang K, Zhang L, Zhang Y. Protein-imprinted material for the treatment of antibiotic-resistant bacteria. Sci Bull (Beijing) 2016. [DOI: 10.1007/s11434-016-1207-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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Non-classical transpeptidases yield insight into new antibacterials. Nat Chem Biol 2016; 13:54-61. [PMID: 27820797 PMCID: PMC5477059 DOI: 10.1038/nchembio.2237] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 08/31/2016] [Indexed: 01/30/2023]
Abstract
Bacterial survival requires an intact peptidoglycan layer, a three-dimensional exoskeleton that encapsulates the cytoplasmic membrane. Historically, the final steps of peptidoglycan synthesis are known to be carried out by D,D-transpeptidases, enzymes that are inhibited by the β-lactams, which constitute >50% of all antibacterials in clinical use. Here, we show that the carbapenem subclass of β-lactams are distinctly effective not only because they inhibit D,D-transpeptidases and are poor substrates for β-lactamases, but primarily because they also inhibit non-classical transpeptidases, namely the L,D-transpeptidases, which generate the majority of linkages in the peptidoglycan of mycobacteria. We have characterized the molecular mechanisms responsible for inhibition of L,D-transpeptidases of Mycobacterium tuberculosis and a range of bacteria including ESKAPE pathogens, and used this information to design, synthesize and test simplified carbapenems with potent antibacterial activity.
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45
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Hoagland DT, Liu J, Lee RB, Lee RE. New agents for the treatment of drug-resistant Mycobacterium tuberculosis. Adv Drug Deliv Rev 2016; 102:55-72. [PMID: 27151308 PMCID: PMC4903924 DOI: 10.1016/j.addr.2016.04.026] [Citation(s) in RCA: 230] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/20/2016] [Accepted: 04/22/2016] [Indexed: 02/06/2023]
Abstract
Inadequate dosing and incomplete treatment regimens, coupled with the ability of the tuberculosis bacilli to cause latent infections that are tolerant of currently used drugs, have fueled the rise of multidrug-resistant tuberculosis (MDR-TB). Treatment of MDR-TB infections is a major clinical challenge that has few viable or effective solutions; therefore patients face a poor prognosis and years of treatment. This review focuses on emerging drug classes that have the potential for treating MDR-TB and highlights their particular strengths as leads including their mode of action, in vivo efficacy, and key medicinal chemistry properties. Examples include the newly approved drugs bedaquiline and delaminid, and other agents in clinical and late preclinical development pipeline for the treatment of MDR-TB. Herein, we discuss the challenges to developing drugs to treat tuberculosis and how the field has adapted to these difficulties, with an emphasis on drug discovery approaches that might produce more effective agents and treatment regimens.
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Affiliation(s)
- Daniel T Hoagland
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Pharmaceutical Sciences Graduate Program, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jiuyu Liu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Robin B Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Richard E Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Li W, Dong K, Ren J, Qu X. A β-Lactamase-Imprinted Responsive Hydrogel for the Treatment of Antibiotic-Resistant Bacteria. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600205] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Wen Li
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
- University of Chinese Academy of Sciences; Beijing 100039 China
| | - Kai Dong
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
- University of Chinese Academy of Sciences; Beijing 100039 China
| | - Jinsong Ren
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
| | - Xiaogang Qu
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
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47
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Li W, Dong K, Ren J, Qu X. A β-Lactamase-Imprinted Responsive Hydrogel for the Treatment of Antibiotic-Resistant Bacteria. Angew Chem Int Ed Engl 2016; 55:8049-53. [DOI: 10.1002/anie.201600205] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/10/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Wen Li
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
- University of Chinese Academy of Sciences; Beijing 100039 China
| | - Kai Dong
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
- University of Chinese Academy of Sciences; Beijing 100039 China
| | - Jinsong Ren
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
| | - Xiaogang Qu
- Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry; Chinese Academy of Sciences; Changchun, Jilin 130022 China
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48
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Fisher JF, Mobashery S. β-Lactam Resistance Mechanisms: Gram-Positive Bacteria and Mycobacterium tuberculosis. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025221. [PMID: 27091943 DOI: 10.1101/cshperspect.a025221] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The value of the β-lactam antibiotics for the control of bacterial infection has eroded with time. Three Gram-positive human pathogens that were once routinely susceptible to β-lactam chemotherapy-Streptococcus pneumoniae, Enterococcus faecium, and Staphylococcus aureus-now are not. Although a fourth bacterium, the acid-fast (but not Gram-positive-staining) Mycobacterium tuberculosis, has intrinsic resistance to earlier β-lactams, the emergence of strains of this bacterium resistant to virtually all other antibiotics has compelled the evaluation of newer β-lactam combinations as possible contributors to the multidrug chemotherapy required to control tubercular infection. The emerging molecular-level understanding of these resistance mechanisms used by these four bacteria provides the conceptual framework for bringing forward new β-lactams, and new β-lactam strategies, for the future control of their infections.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
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The RipA and RipB Peptidoglycan Endopeptidases Are Individually Nonessential to Mycobacterium smegmatis. J Bacteriol 2016; 198:1464-75. [PMID: 26977111 DOI: 10.1128/jb.00059-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 02/23/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Mycobacteria possess a series of Rip peptidoglycan endopeptidases that have been characterized in various levels of detail. The RipA and RipB proteins have been extensively studied and are DL-endopeptidases, and RipA has been considered essential to Mycobacterium smegmatis and Mycobacterium tuberculosis We show here that the ripA and ripB genes are individually dispensable in M. smegmatis and that at least one of the genes must be expressed for viability. We characterized strains carrying in-frame deletion mutations of ripA and ripB and found that both mutant strains exhibited increased susceptibility to a limited number of antibiotics and to detergent but that only the ΔripA mutant displayed hypersusceptibility to lysozyme. We also constructed and characterized ΔripD and ΔripAΔripD mutants and found that the single mutant had only an intermediate lysozyme hypersusceptibility phenotype compared to that of wild-type cells while loss of ripD in the ΔripA background partially rescued the antibiotic and lysozyme phenotypes of the ΔripA mutant. IMPORTANCE We show that the RipA endopeptidase, which has been considered essential for cell division in certain mycobacteria, is not essential but that at least it or a similar protein, RipB, must be expressed by the bacteria for viability. This work is the first description of strains carrying single deletion mutations of RipA, RipB, and a novel endopeptidase-like protein, RipD.
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50
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Peptidoglycan synthesis in Mycobacterium tuberculosis is organized into networks with varying drug susceptibility. Proc Natl Acad Sci U S A 2015; 112:13087-92. [PMID: 26438867 DOI: 10.1073/pnas.1514135112] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Peptidoglycan (PG), a complex polymer composed of saccharide chains cross-linked by short peptides, is a critical component of the bacterial cell wall. PG synthesis has been extensively studied in model organisms but remains poorly understood in mycobacteria, a genus that includes the important human pathogen Mycobacterium tuberculosis (Mtb). The principle PG synthetic enzymes have similar and, at times, overlapping functions. To determine how these are functionally organized, we carried out whole-genome transposon mutagenesis screens in Mtb strains deleted for ponA1, ponA2, and ldtB, major PG synthetic enzymes. We identified distinct factors required to sustain bacterial growth in the absence of each of these enzymes. We find that even the homologs PonA1 and PonA2 have unique sets of genetic interactions, suggesting there are distinct PG synthesis pathways in Mtb. Either PonA1 or PonA2 is required for growth of Mtb, but both genetically interact with LdtB, which has its own distinct genetic network. We further provide evidence that each interaction network is differentially susceptible to antibiotics. Thus, Mtb uses alternative pathways to produce PG, each with its own biochemical characteristics and vulnerabilities.
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