1
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Su HL, Lai SJ, Tsai KC, Fung KM, Lung TL, Hsu HM, Wu YC, Liu CH, Lai HX, Lin JH, Tseng TS. Structure-guided identification and characterization of potent inhibitors targeting PhoP and MtrA to combat mycobacteria. Comput Struct Biotechnol J 2024; 23:1477-1488. [PMID: 38623562 PMCID: PMC11016868 DOI: 10.1016/j.csbj.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 04/01/2024] [Accepted: 04/01/2024] [Indexed: 04/17/2024] Open
Abstract
Mycobacteria are causative agents of tuberculosis (TB), which is a global health concern. Drug-resistant TB strains are rapidly emerging, thereby necessitating the urgent development of new drugs. Two-component signal transduction systems (TCSs) are signaling pathways involved in the regulation of various bacterial behaviors and responses to environmental stimuli. Applying specific inhibitors of TCSs can disrupt bacterial signaling, growth, and virulence, and can help combat drug-resistant TB. We conducted a comprehensive pharmacophore-based inhibitor screening and biochemical and biophysical examinations to identify, characterize, and validate potential inhibitors targeting the response regulators PhoP and MtrA of mycobacteria. The constructed pharmacophore model Phar-PR-n4 identified effective inhibitors of formation of the PhoP-DNA complex: ST132 (IC50 = 29 ± 1.6 µM) and ST166 (IC50 = 18 ± 1.3 µM). ST166 (KD = 18.4 ± 4.3 μM) and ST132 (KD = 14.5 ± 0.1 μM) strongly targeted PhoP in a slow-on, slow-off manner. The inhibitory potency and binding affinity of ST166 and ST132 for MtrAC were comparable to those of PhoP. Structural analyses and molecular dynamics simulations revealed that ST166 and ST132 mainly interact with the α8-helix and C-terminal β-hairpin of PhoP, with functionally essential residue hotspots for structure-based inhibitor optimization. Moreover, ST166 has in vitro antibacterial activity against Macrobacterium marinum. Thus, ST166, with its characteristic 1,2,5,6-tetrathiocane and terminal sulphonic groups, has excellent potential as a candidate for the development of novel antimicrobial agents to combat pathogenic mycobacteria.
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Affiliation(s)
- Han-Li Su
- Department of Emergency Medicine, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 600, Taiwan
| | - Shu-Jung Lai
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
- Research Center for Cancer Biology, China Medical University, Taichung, Taiwan
| | - Keng-Chang Tsai
- National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei, Taiwan
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Kit-Man Fung
- Biomedical Translation Research Center (BioTReC), Academia Sinica, Taipei 11529, Taiwan
| | - Tse-Lin Lung
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
| | - Hsing-Mien Hsu
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
| | - Yi-Chen Wu
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
| | - Ching-Hui Liu
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
| | - Hui-Xiang Lai
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
| | - Jiun-Han Lin
- Department of Industrial Technology, Ministry of Economic Affairs, Taipei, Taiwan
- Food Industry Research and Development Institute, Hsinchu City, Taiwan
| | - Tien-Sheng Tseng
- Institute of Molecular Biology, National Chung Hsing University, Taichung,Taiwan
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2
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Singh S, Singh S, Trivedi M, Dwivedi M. An insight into MDR Acinetobacter baumannii infection and its pathogenesis: Potential therapeutic targets and challenges. Microb Pathog 2024; 192:106674. [PMID: 38714263 DOI: 10.1016/j.micpath.2024.106674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 04/22/2024] [Accepted: 05/01/2024] [Indexed: 05/09/2024]
Abstract
Acinetobacter baumannii is observed as a common species of Gram-negative bacteria that exist in soil and water. Despite being accepted as a typical component of human skin flora, it has become an important opportunistic pathogen, especially in healthcare settings. The pathogenicity of A. baumannii is attributed to its virulence factors, which include adhesins, pili, lipopolysaccharides, outer membrane proteins, iron uptake systems, autotransporter, secretion systems, phospholipases etc. These elements provide the bacterium the ability to cling to and penetrate host cells, get past the host immune system, and destroy tissue. Its infection is a major contributor to human pathophysiological conditions including pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. It is challenging to treat infections brought on by this pathogen since this bacterium has evolved to withstand numerous drugs and further emergence of drug-resistant A. baumannii results in higher rates of morbidity and mortality. The long-term survival of this bacterium on surfaces of medical supplies and hospital furniture facilitates its frequent spread in humans from one habitat to another. There is a need for urgent investigations to find effective drug targets for A. baumannii as well as designing novel drugs to reduce the survival and spread of infection. In the current review, we represent the specific features, pathogenesis, and molecular intricacies of crucial drug targets of A. baumannii. This would also assist in proposing strategies and alternative therapies for the prevention and treatment of A. baumannii infections and their spread.
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Affiliation(s)
- Sukriti Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Sushmita Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Mala Trivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India; Research Cell, Amity University Uttar Pradesh, Lucknow, 226028, India.
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3
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Stabile M, Esposito A, Iula VD, Guaragna A, De Gregorio E. PYED-1 Overcomes Colistin Resistance in Acinetobacter baumannii. Pathogens 2023; 12:1323. [PMID: 38003788 PMCID: PMC10674209 DOI: 10.3390/pathogens12111323] [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: 10/06/2023] [Revised: 10/21/2023] [Accepted: 10/31/2023] [Indexed: 11/26/2023] Open
Abstract
Antibiotic resistance has become more and more widespread over the recent decades, becoming a major global health problem and causing colistin to be increasingly used as an antibiotic of last resort. Acinetobacter baumannii, an opportunistic pathogen that has rapidly evolved into a superbug exhibiting multidrug-resistant phenotypes, is responsible for a large number of hospital infection outbreaks. With the intensive use of colistin, A. baumannii resistance to colistin has been found to increase significantly. In previous work, we identified a deflazacort derivative, PYED-1 (pregnadiene-11-hydroxy-16,17-epoxy-3,20-dione-1), which exhibits either direct-acting or synergistic activity against Gram-positive and Gram-negative species and Candida spp., including A. baumannii. The aim of this study was to evaluate the antibacterial activity of PYED-1 in combination with colistin against both A. baumannii planktonic and sessile cells. Furthermore, the cytotoxicity of PYED-1 with and without colistin was assessed. Our results show that PYED-1 and colistin can act synergistically to produce a strong antimicrobial effect against multidrug-resistant populations of A. baumannii. Interestingly, our data reveal that PYED-1 is able to restore the efficacy of colistin against all colistin-resistant A. baumannii isolates. This drug combination could achieve a much stronger antimicrobial effect than colistin while using a much smaller dosage of the drugs, additionally eliminating the toxicity and resistance issues associated with the use of colistin.
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Affiliation(s)
- Maria Stabile
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126 Naples, Italy; (M.S.); (A.G.)
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
| | - Anna Esposito
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale V. Tecchio 80, 80125 Naples, Italy;
| | - Vita Dora Iula
- Department of Laboratory Medicine, U.O.C Patologia Clinica, Ospedale del Mare—ASL Napoli1 Centro, 80145 Naples, Italy;
| | - Annalisa Guaragna
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 80126 Naples, Italy; (M.S.); (A.G.)
| | - Eliana De Gregorio
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy
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4
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Crotteau AN, Hubble VB, Marrujo SA, Mattingly AE, Melander RJ, Melander C. Sensitization of Gram-Negative Bacteria to Aminoglycosides with 2-Aminoimidazole Adjuvants. Antibiotics (Basel) 2023; 12:1563. [PMID: 37998765 PMCID: PMC10668796 DOI: 10.3390/antibiotics12111563] [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: 09/25/2023] [Revised: 10/20/2023] [Accepted: 10/21/2023] [Indexed: 11/25/2023] Open
Abstract
In 2019, five million deaths associated with antimicrobial resistance were reported by The Centers for Disease Control and Prevention (CDC). Acinetobacter baumannii, a Gram-negative bacterial pathogen, is among the list of urgent threats. Previously, we reported 2-aminoimidazole (2-AI) adjuvants that potentiate macrolide activity against A. baumannii. In this study, we identify several of these adjuvants that sensitize A. baumannii to aminoglycoside antibiotics. Lead compounds 1 and 7 lower the tobramycin (TOB) minimum inhibitory concentration (MIC) against the TOB-resistant strain AB5075 from 128 μg/mL to 2 μg/mL at 30 μM. In addition, the lead compounds lower the TOB MIC against the TOB-susceptible strain AB19606 from 4 μg/mL to 1 μg/mL and 0.5 μg/mL, respectively, at 30 μM and 15 μM. The evolution of resistance to TOB and 1 in AB5075 revealed mutations in genes related to protein synthesis, the survival of bacteria under environmental stressors, bacteriophages, and proteins containing Ig-like domains.
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Affiliation(s)
| | | | | | | | | | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; (A.N.C.)
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5
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Rogga V, Kosalec I. Untying the anchor for the lipopolysaccharide: lipid A structural modification systems offer diagnostic and therapeutic options to tackle polymyxin resistance. Arh Hig Rada Toksikol 2023; 74:145-166. [PMID: 37791675 PMCID: PMC10549895 DOI: 10.2478/aiht-2023-74-3717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/01/2023] [Accepted: 07/01/2023] [Indexed: 10/05/2023] Open
Abstract
Polymyxin antibiotics are the last resort for treating patients in intensive care units infected with multiple-resistant Gram-negative bacteria. Due to their polycationic structure, their mode of action is based on an ionic interaction with the negatively charged lipid A portion of the lipopolysaccharide (LPS). The most prevalent polymyxin resistance mechanisms involve covalent modifications of lipid A: addition of the cationic sugar 4-amino-L-arabinose (L-Ara4N) and/or phosphoethanolamine (pEtN). The modified structure of lipid A has a lower net negative charge, leading to the repulsion of polymyxins and bacterial resistance to membrane disruption. Genes encoding the enzymatic systems involved in these modifications can be transferred either through chromosomes or mobile genetic elements. Therefore, new approaches to resistance diagnostics have been developed. On another note, interfering with these enzymatic systems might offer new therapeutic targets for drug discovery. This literature review focuses on diagnostic approaches based on structural changes in lipid A and on the therapeutic potential of molecules interfering with these changes.
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Affiliation(s)
- Vanessa Rogga
- University of Zagreb Faculty of Pharmacy and Biochemistry, Department of Microbiology, Zagreb, Croatia
| | - Ivan Kosalec
- University of Zagreb Faculty of Pharmacy and Biochemistry, Department of Microbiology, Zagreb, Croatia
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6
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Wang Q, Kim H, Halvorsen TM, Chen S, Hayes CS, Buie CR. Leveraging microfluidic dielectrophoresis to distinguish compositional variations of lipopolysaccharide in E. coli. Front Bioeng Biotechnol 2023; 11:991784. [PMID: 36873367 PMCID: PMC9979706 DOI: 10.3389/fbioe.2023.991784] [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: 07/12/2022] [Accepted: 02/03/2023] [Indexed: 02/18/2023] Open
Abstract
Lipopolysaccharide (LPS) is the unique feature that composes the outer leaflet of the Gram-negative bacterial cell envelope. Variations in LPS structures affect a number of physiological processes, including outer membrane permeability, antimicrobial resistance, recognition by the host immune system, biofilm formation, and interbacterial competition. Rapid characterization of LPS properties is crucial for studying the relationship between these LPS structural changes and bacterial physiology. However, current assessments of LPS structures require LPS extraction and purification followed by cumbersome proteomic analysis. This paper demonstrates one of the first high-throughput and non-invasive strategies to directly distinguish Escherichia coli with different LPS structures. Using a combination of three-dimensional insulator-based dielectrophoresis (3DiDEP) and cell tracking in a linear electrokinetics assay, we elucidate the effect of structural changes in E. coli LPS oligosaccharides on electrokinetic mobility and polarizability. We show that our platform is sufficiently sensitive to detect LPS structural variations at the molecular level. To correlate electrokinetic properties of LPS with the outer membrane permeability, we further examined effects of LPS structural variations on bacterial susceptibility to colistin, an antibiotic known to disrupt the outer membrane by targeting LPS. Our results suggest that microfluidic electrokinetic platforms employing 3DiDEP can be a useful tool for isolating and selecting bacteria based on their LPS glycoforms. Future iterations of these platforms could be leveraged for rapid profiling of pathogens based on their surface LPS structural identity.
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Affiliation(s)
- Qianru Wang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Hyungseok Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Tiffany M Halvorsen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Sijie Chen
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Christopher S Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Cullen R Buie
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
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7
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Koh Jing Jie A, Hussein M, Rao GG, Li J, Velkov T. Drug Repurposing Approaches towards Defeating Multidrug-Resistant Gram-Negative Pathogens: Novel Polymyxin/Non-Antibiotic Combinations. Pathogens 2022; 11:pathogens11121420. [PMID: 36558754 PMCID: PMC9781023 DOI: 10.3390/pathogens11121420] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/18/2022] [Accepted: 11/23/2022] [Indexed: 11/30/2022] Open
Abstract
Multidrug-resistant (MDR) Gram-negative pathogens remain an unmet public health threat. In recent times, increased rates of resistance have been reported not only to commonly used antibiotics, but also to the last-resort antibiotics, such as polymyxins. More worryingly, despite the current trends in resistance, there is a lack of new antibiotics in the drug-discovery pipeline. Hence, it is imperative that new strategies are developed to preserve the clinical efficacy of the current antibiotics, particularly the last-line agents. Combining conventional antibiotics such as polymyxins with non-antibiotics (or adjuvants), has emerged as a novel and effective strategy against otherwise untreatable MDR pathogens. This review explores the available literature detailing the latest polymyxin/non-antibiotic combinations, their mechanisms of action, and potential avenues to advance their clinical application.
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Affiliation(s)
- Augustine Koh Jing Jie
- Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Maytham Hussein
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Gauri G. Rao
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jian Li
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Tony Velkov
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
- Correspondence:
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8
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Thymol as an Adjuvant to Restore Antibiotic Efficacy and Reduce Antimicrobial Resistance and Virulence Gene Expression in Enterotoxigenic Escherichia coli Strains. Antibiotics (Basel) 2022; 11:antibiotics11081073. [PMID: 36009942 PMCID: PMC9404878 DOI: 10.3390/antibiotics11081073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 11/29/2022] Open
Abstract
The continuous spread of antimicrobial resistance is endangering the efficient control of enterotoxigenic Escherichia coli (ETEC), which is mainly responsible for post-weaning diarrhea onset in piglets. Thymol, the key constituent of thyme essential oil, is already used in animal nutrition for its antimicrobial action. The aim of this study was to investigate the potential adjuvant effect of thymol to re-establish antibiotic efficacy against highly resistant ETEC field strains. Secondly, we evaluated the modulation of virulence and antibiotic resistance genes. Thymol showed the capacity to control ETEC growth and, when combined with ineffective antibiotics, it increased their antimicrobial power. In particular, it showed significant effects when blended with colistin and tetracycline, suggesting that the adjuvant effects rely on the presence of complementary mechanisms of action between molecules, or the absence of resistance mechanisms that inactivate antibiotics and target sites. Furthermore, our findings demonstrate that, when added to antibiotics, thymol can help to further downregulate several virulence and antibiotic resistance genes, offering new insights on the potential mechanisms of action. Therefore, in a one-health approach, our study supports the beneficial effects of combining thymol with antibiotics to restore their efficacy, together with the possibility of targeting gene expression as a pioneering approach to manage ETEC pathogenicity.
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9
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Structure-Activity Relationship Studies of [1,2,5]Oxadiazolo[3,4-b]pyrazine-Containing Polymyxin-Selective Resistance-Modifying Agents. Bioorg Med Chem Lett 2022; 72:128878. [PMID: 35788034 PMCID: PMC10101151 DOI: 10.1016/j.bmcl.2022.128878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/17/2022] [Accepted: 06/29/2022] [Indexed: 11/22/2022]
Abstract
Multidrug-resistant (MDR) Gram-negative bacteria are an urgent and rapidly spreading threat to human health with limited treatment options. Previously, we discovered a novel [1,2,5]oxadiazolo[3,4-b]pyrazine-containing compound (1) that selectively re-sensitized a variety of MDR Gram-negative bacteria to colistin, one of the last-resort antibiotic. Herein, we report the structure-activity relationship studies of compound 1 that led to the discovery of several more potent and/or less toxic resistance-modifying agents (RMAs). Further evaluation of these RMAs showed that they were effective in a wide range of MDR bacteria. These results demonstrated these compounds as a novel class of RMAs and may be further developed as therapeutic agents.
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10
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Srikanth D, Vinayak Joshi S, Ghouse Shaik M, Pawar G, Bujji S, Kanchupalli V, Chopra S, Nanduri S. A Comprehensive Review on Potential Therapeutic Inhibitors of Nosocomial Acinetobacter baumannii Superbugs. Bioorg Chem 2022; 124:105849. [DOI: 10.1016/j.bioorg.2022.105849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 12/20/2022]
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11
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Gao Y, Dutta S, Wang X. Serendipitous Discovery of a Highly Active and Selective Resistance-Modifying Agent for Colistin-Resistant Gram-Negative Bacteria. ACS OMEGA 2022; 7:12442-12446. [PMID: 35449921 PMCID: PMC9016814 DOI: 10.1021/acsomega.2c01530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 03/21/2022] [Indexed: 05/03/2023]
Abstract
Antibiotic resistance is a growing global health concern. Colistin is one of the last-resort antibiotics that treats multidrug-resistant (MDR) Gram-negative bacterial infection. However, bacteria resistant to colistin have become increasingly prevalent. Using a bacterial whole-cell screen of a fragment-based library, one compound was discovered to resensitize MDR Escherichia coli AR-0493 to colistin with low mammalian toxicity. Interestingly, postscreening validation studies identified a highly related yet distinct compound as the actual substance responsible for the activity. Further studies showed that this novel resistance-modifying agent is not only very potent but also highly selective to potentiate the activity of polymyxin family antibiotics in a wide range of MDR Gram-negative bacteria. Thus, it may be further developed as a combination therapy to prolong the life span of colistin in the clinic.
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12
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Belardinelli JM, Li W, Martin KH, Zeiler MJ, Lian E, Avanzi C, Wiersma CJ, Nguyen TV, Angala B, de Moura VCN, Jones V, Borlee BR, Melander C, Jackson M. 2-Aminoimidazoles Inhibit Mycobacterium abscessus Biofilms in a Zinc-Dependent Manner. Int J Mol Sci 2022; 23:ijms23062950. [PMID: 35328372 PMCID: PMC8951752 DOI: 10.3390/ijms23062950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 02/28/2022] [Accepted: 03/07/2022] [Indexed: 02/04/2023] Open
Abstract
Biofilm growth is thought to be a significant obstacle to the successful treatment of Mycobacterium abscessus infections. A search for agents capable of inhibiting M. abscessus biofilms led to our interest in 2-aminoimidazoles and related scaffolds, which have proven to display antibiofilm properties against a number of Gram-negative and Gram-positive bacteria, including Mycobacterium tuberculosis and Mycobacterium smegmatis. The screening of a library of 30 compounds led to the identification of a compound, AB-2-29, which inhibits the formation of M. abscessus biofilms with an IC50 (the concentration required to inhibit 50% of biofilm formation) in the range of 12.5 to 25 μM. Interestingly, AB-2-29 appears to chelate zinc, and its antibiofilm activity is potentiated by the addition of zinc to the culture medium. Preliminary mechanistic studies indicate that AB-2-29 acts through a distinct mechanism from those reported to date for 2-aminoimidazole compounds.
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Affiliation(s)
- Juan M. Belardinelli
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Wei Li
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Kevin H. Martin
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (K.H.M.); (B.R.B.)
| | - Michael J. Zeiler
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; (M.J.Z.); (C.M.)
| | - Elena Lian
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Charlotte Avanzi
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Crystal J. Wiersma
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Tuan Vu Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, NC 27607, USA;
| | - Bhanupriya Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Vinicius C. N. de Moura
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Victoria Jones
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
| | - Bradley R. Borlee
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (K.H.M.); (B.R.B.)
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; (M.J.Z.); (C.M.)
- Department of Chemistry, North Carolina State University, Raleigh, NC 27607, USA;
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA; (J.M.B.); (W.L.); (E.L.); (C.A.); (C.J.W.); (B.A.); (V.C.N.d.M.); (V.J.)
- Correspondence: ; Tel.: +1-(970)-491-3582
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13
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Riu F, Ruda A, Engström O, Muheim C, Mobarak H, Ståhle J, Kosma P, Carta A, Daley DO, Widmalm G. A Lead-Based Fragment Library Screening of the Glycosyltransferase WaaG from Escherichia coli. Pharmaceuticals (Basel) 2022; 15:ph15020209. [PMID: 35215321 PMCID: PMC8877264 DOI: 10.3390/ph15020209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 02/05/2022] [Accepted: 02/06/2022] [Indexed: 11/16/2022] Open
Abstract
Glucosyl transferase I (WaaG) in E. coli catalyzes the transfer of an α-d-glucosyl group to the inner core of the lipopolysaccharide (LPS) and plays an important role in the biogenesis of the outer membrane. If its activity could be inhibited, the integrity of the outer membrane would be compromised and the bacterium would be susceptible to antibiotics that are normally prevented from entering the cell. Herein, three libraries of molecules (A, B and C) were docked in the binding pocket of WaaG, utilizing the docking binding affinity as a filter to select fragment-based compounds for further investigations. From the results of the docking procedure, a selection of compounds was investigated by molecular dynamics (MD) simulations to obtain binding free energy (BFE) and KD values for ligands as an evaluation for the binding to WaaG. Derivatives of 1,3-thiazoles (A7 and A4) from library A and 1,3,4-thiadiazole (B33) from library B displayed a promising profile of BFE, with KD < mM, viz., 0.11, 0.62 and 0.04 mM, respectively. Further root-mean-square-deviation (RMSD), electrostatic/van der Waals contribution to the binding and H-bond interactions displayed a favorable profile for ligands A4 and B33. Mannose and/or heptose-containing disaccharides C1–C4, representing sub-structures of the inner core of the LPS, were also investigated by MD simulations, and compound C42− showed a calculated KD = 0.4 µM. In the presence of UDP-Glc2−, the best-docked pose of disaccharide C42− is proximate to the glucose-binding site of WaaG. A study of the variation in angle and distance was performed on the different portions of WaaG (N-, the C- domains and the hinge region). The Spearman correlation coefficient between the two variables was close to unity, where both variables increase in the same way, suggesting a conformational rearrangement of the protein during the MD simulation, revealing molecular motions of the enzyme that may be part of the catalytic cycle. Selected compounds were also analyzed by Saturation Transfer Difference (STD) NMR experiments. STD effects were notable for the 1,3-thiazole derivatives A4, A8 and A15 with the apo form of the protein as well as in the presence of UDP for A4.
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Affiliation(s)
- Federico Riu
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Via Muroni, 23A, 07100 Sassari, Italy; (F.R.); (A.C.)
| | - Alessandro Ruda
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Olof Engström
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Claudio Muheim
- Arrhenius Laboratory, Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden; (C.M.); (D.O.D.)
| | - Hani Mobarak
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Jonas Ståhle
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
| | - Paul Kosma
- Department of Chemistry, University of Natural Resources and Life Sciences—Vienna, 1190 Vienna, Austria;
| | - Antonio Carta
- Department of Medical, Surgical and Experimental Sciences, University of Sassari, Via Muroni, 23A, 07100 Sassari, Italy; (F.R.); (A.C.)
| | - Daniel O. Daley
- Arrhenius Laboratory, Department of Biochemistry and Biophysics, Stockholm University, S-106 91 Stockholm, Sweden; (C.M.); (D.O.D.)
| | - Göran Widmalm
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (O.E.); (H.M.); (J.S.)
- Correspondence:
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14
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Tiwari V, Panta PR, Billiot CE, Douglass MV, Herrera CM, Trent MS, Doerrler WT. A Klebsiella pneumoniae DedA family membrane protein is required for colistin resistance and for virulence in wax moth larvae. Sci Rep 2021; 11:24365. [PMID: 34934166 PMCID: PMC8692421 DOI: 10.1038/s41598-021-03834-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/10/2021] [Indexed: 12/15/2022] Open
Abstract
Ineffectiveness of carbapenems against multidrug resistant pathogens led to the increased use of colistin (polymyxin E) as a last resort antibiotic. A gene belonging to the DedA family encoding conserved membrane proteins was previously identified by screening a transposon library of K. pneumoniae ST258 for sensitivity to colistin. We have renamed this gene dkcA (dedA of Klebsiella required for colistin resistance). DedA family proteins are likely membrane transporters required for viability of Escherichia coli and Burkholderia spp. at alkaline pH and for resistance to colistin in a number of bacterial species. Colistin resistance is often conferred via modification of the lipid A component of bacterial lipopolysaccharide with aminoarabinose (Ara4N) and/or phosphoethanolamine. Mass spectrometry analysis of lipid A of the ∆dkcA mutant shows a near absence of Ara4N in the lipid A, suggesting a requirement for DkcA for lipid A modification with Ara4N. Mutation of K. pneumoniae dkcA resulted in a reduction of the colistin minimal inhibitory concentration to approximately what is found with a ΔarnT strain. We also identify a requirement of DkcA for colistin resistance that is independent of lipid A modification, instead requiring maintenance of optimal membrane potential. K. pneumoniae ΔdkcA displays reduced virulence in Galleria mellonella suggesting colistin sensitivity can cause loss of virulence.
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Affiliation(s)
- Vijay Tiwari
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Pradip R. Panta
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Caitlin E. Billiot
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Martin V. Douglass
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - Carmen M. Herrera
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - M. Stephen Trent
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - William T. Doerrler
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
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15
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Melander RJ, Mattingly AE, Melander C. Phenotypic screening of compound libraries as a platform for the identification of antibiotic adjuvants: Identification of colistin adjuvants from a natural product library. Methods Enzymol 2021; 665:153-176. [PMID: 35379433 PMCID: PMC10942738 DOI: 10.1016/bs.mie.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The identification of antibiotic adjuvants, small molecules that potentiate the activity of conventional antibiotics, provides an orthogonal approach to the development of new antibiotics in the fight against drug resistant bacterial infections. Methods to identify novel adjuvants could potentially aid efforts to overcome the increasing prevalence of resistance and stave off the onset of a "post-antibiotic era." Phenotypic whole cell screens allow for the identification of hits with the necessary properties to access their biomolecular target, and may also facilitate the discovery of novel adjuvant targets. A phenotypic screening platform is outlined, in which a natural product library was explored for activity with antibiotics from several mechanistically distinct classes against clinically important bacterial species. General approaches to delineating the mechanism of action of hit compounds identified from phenotypic screens are described, followed by specific approaches to uncovering the mechanism of action of the colistin adjuvants identified from the natural product screen.
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Affiliation(s)
- Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
| | - Anne E Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States.
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16
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Scarbrough BA, Eade CR, Reid AJ, Williams TC, Troutman JM. Lipopolysaccharide Is a 4-Aminoarabinose Donor to Exogenous Polyisoprenyl Phosphates through the Reverse Reaction of the Enzyme ArnT. ACS OMEGA 2021; 6:25729-25741. [PMID: 34632229 PMCID: PMC8495848 DOI: 10.1021/acsomega.1c04036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Indexed: 05/11/2023]
Abstract
Modification of the lipid A portion of LPS with cationic monosaccharides provides resistance to polymyxins, which are often employed as a last resort to treat multidrug-resistant bacterial infections. Here, we describe the use of fluorescent polyisoprenoids, liquid chromatography-mass spectrometry, and bacterial genetics to probe the activity of membrane-localized proteins that utilize the 55-carbon lipid carrier bactoprenyl phosphate (BP). We have discovered that a substantial background reaction occurs when B-strain E. coli cell membrane fractions are supplemented with exogenous BP. This reaction involves proteins associated with the arn operon, which is necessary for the covalent modification of lipid A with the cationic 4-aminoarabinose (Ara4N). Using a series of arn operon gene deletion mutants, we identified that the modification was dependent on ArnC, which is responsible for forming BP-linked Ara4N, or ArnT, which transfers Ara4N to lipid A. Surprisingly, we found that the majority of the Ara4N-modified isoprenoid was due to the reverse reaction catalyzed by ArnT and demonstrate this using heat-inactivated membrane fractions, isolated lipopolysaccharide fractions, and analyses of a purified ArnT. This work provides methods that will facilitate thorough and rapid investigation of bacterial outer membrane remodeling and the evaluation of polyisoprenoid precursors required for covalent glycan modifications.
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Affiliation(s)
- Beth A. Scarbrough
- Nanoscale
Science Program, The University of North
Carolina at Charlotte, Charlotte, North Carolina 28223-0001, United States
| | - Colleen R. Eade
- Department
of Chemistry, The University of North Carolina
at Charlotte, Charlotte, North Carolina 28223-0001, United States
| | - Amanda J. Reid
- Nanoscale
Science Program, The University of North
Carolina at Charlotte, Charlotte, North Carolina 28223-0001, United States
| | - Tiffany C. Williams
- Department
of Chemistry, The University of North Carolina
at Charlotte, Charlotte, North Carolina 28223-0001, United States
| | - Jerry M. Troutman
- Department
of Chemistry, The University of North Carolina
at Charlotte, Charlotte, North Carolina 28223-0001, United States
- Nanoscale
Science Program, The University of North
Carolina at Charlotte, Charlotte, North Carolina 28223-0001, United States
- . Phone: 704-687-5180
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17
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Zhang Z, Ortega D, Rush A, Blankenship LR, Cheng ZJ, Moore RE, Tran MLN, Sandoval LG, Aboulhosn K, Watanabe S, Cortez KS, Perlman DH, Semmelhack MF, Miller Conrad LC. Antibiotic Adjuvant Activity Revealed in a Photoaffinity Approach to Determine the Molecular Target of Antipyocyanin Compounds. ACS Infect Dis 2021; 7:535-543. [PMID: 33587590 DOI: 10.1021/acsinfecdis.0c00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Infections with Pseudomonas aeruginosa are a looming threat to public health. New treatment strategies are needed to combat this pathogen, for example, by blocking the production of virulence factors like pyocyanin. A photoaffinity analogue of an antipyocyanin compound was developed to interrogate the inhibitor's molecular mechanism of action. While we sought to develop antivirulence inhibitors, the proteomics results suggested that the compounds had antibiotic adjuvant activity. Unexpectedly, we found that these compounds amplify the bactericidal activity of colistin, a well-characterized antibiotic, suggesting they may represent a first-in-class antibiotic adjuvant therapy. Analogues have the potential not only to widen the therapeutic index of cationic antimicrobial peptides like colistin, but also to be effective against colistin-resistant strains, strengthening our arsenal to combat P. aeruginosa infections.
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Affiliation(s)
- Zinan Zhang
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Dominic Ortega
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Anthony Rush
- Department of Bioengineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States
| | - Lauren R. Blankenship
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Zi Jun Cheng
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Rebecca E. Moore
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Minh L. N. Tran
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Lucero G. Sandoval
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Kareem Aboulhosn
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Seiichiro Watanabe
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - Kendra S. Cortez
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
| | - David H. Perlman
- Princeton Proteomics and Mass Spectrometry Center, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Martin F. Semmelhack
- Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
| | - Laura C. Miller Conrad
- Department of Chemistry, San José State University, 1 Washington Square, San Jose, California 95192, United States
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Septal Class A Penicillin-Binding Protein Activity and ld-Transpeptidases Mediate Selection of Colistin-Resistant Lipooligosaccharide-Deficient Acinetobacter baumannii. mBio 2021; 12:mBio.02185-20. [PMID: 33402533 PMCID: PMC8545086 DOI: 10.1128/mbio.02185-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Despite dogma suggesting that lipopolysaccharide/lipooligosaccharide (LOS) was essential for viability of Gram-negative bacteria, several Acinetobacter baumannii clinical isolates produced LOS− colonies after colistin selection. Inactivation of the conserved class A penicillin-binding protein, PBP1A, was a compensatory mutation that supported isolation of LOS−A. baumannii, but the impact of PBP1A mutation was not characterized. Here, we show that the absence of PBP1A causes septation defects and that these, together with ld-transpeptidase activity, support isolation of LOS−A. baumannii. PBP1A contributes to proper cell division in A. baumannii, and its absence induced cell chaining. Only isolates producing three or more septa supported selection of colistin-resistant LOS−A. baumannii. PBP1A was enriched at the midcell, where the divisome complex facilitates daughter cell formation, and its localization was dependent on glycosyltransferase activity. Transposon mutagenesis showed that genes encoding two putative ld-transpeptidases (LdtJ and LdtK) became essential in the PBP1A mutant. Both LdtJ and LdtK were required for selection of LOS−A. baumannii, but each had distinct enzymatic activities in the cell. Together, these findings demonstrate that defects in PBP1A glycosyltransferase activity and ld-transpeptidase activity remodel the cell envelope to support selection of colistin-resistant LOS−A. baumannii.
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19
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Are antibacterial effects of non-antibiotic drugs random or purposeful because of a common evolutionary origin of bacterial and mammalian targets? Infection 2020; 49:569-589. [PMID: 33325009 PMCID: PMC7737717 DOI: 10.1007/s15010-020-01547-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/28/2020] [Indexed: 01/09/2023]
Abstract
Purpose Advances in structural biology, genetics, bioinformatics, etc. resulted in the availability of an enormous pool of information enabling the analysis of the ancestry of pro- and eukaryotic genes and proteins. Methods This review summarizes findings of structural and/or functional homologies of pro- and eukaryotic enzymes catalysing analogous biological reactions because of their highly conserved active centres so that non-antibiotics interacted with bacterial targets. Results Protease inhibitors such as staurosporine or camostat inhibited bacterial serine/threonine or serine/tyrosine protein kinases, serine/threonine phosphatases, and serine/threonine kinases, to which penicillin-binding-proteins are linked, so that these drugs synergized with β-lactams, reverted aminoglycoside-resistance and attenuated bacterial virulence. Calcium antagonists such as nitrendipine or verapamil blocked not only prokaryotic ion channels but interacted with negatively charged bacterial cell membranes thus disrupting membrane energetics and inducing membrane stress response resulting in inhibition of P-glycoprotein such as bacterial pumps thus improving anti-mycobacterial activities of rifampicin, tetracycline, fluoroquinolones, bedaquilin and imipenem-activity against Acinetobacter spp. Ciclosporine and tacrolimus attenuated bacterial virulence. ACE-inhibitors like captopril interacted with metallo-β-lactamases thus reverting carbapenem-resistance; prokaryotic carbonic anhydrases were inhibited as well resulting in growth impairment. In general, non-antibiotics exerted weak antibacterial activities on their own but synergized with antibiotics, and/or reverted resistance and/or attenuated virulence. Conclusions Data summarized in this review support the theory that prokaryotic proteins represent targets for non-antibiotics because of a common evolutionary origin of bacterial- and mammalian targets resulting in highly conserved active centres of both, pro- and eukaryotic proteins with which the non-antibiotics interact and exert antibacterial actions.
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20
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Mattingly AE, Cox KE, Smith R, Melander RJ, Ernst RK, Melander C. Screening an Established Natural Product Library Identifies Secondary Metabolites That Potentiate Conventional Antibiotics. ACS Infect Dis 2020; 6:2629-2640. [PMID: 32810395 DOI: 10.1021/acsinfecdis.0c00259] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Health organizations worldwide have warned that we are on the cusp of a "post-antibiotic era," necessitating new approaches to combat antibiotic resistant infections. One such approach is the development of antibiotic adjuvants, which have little or no inherent antibiotic activity at their active concentrations but instead potentiate the activity of antibiotics against antibiotic-resistant bacteria. Recently, we demonstrated that meridianin D, a natural product originally reported to have activity against Staphylococcus aureus and Mycobacterium tuberculosis, possesses the ability to reverse colistin resistance in colistin resistant bacteria. As most natural product screens typically involve screening for only certain activities (anticancer, antiviral, and antimicrobial are typical), we posited that the meridianin D discovery was not unique and there are potentially many natural products that have adjuvant activity. To explore this, the National Cancer Institute (NCI) Natural Product Library Set IV was screened for adjuvant activity using four classes of antibiotics (β-lactams, aminoglycosides, macrolides, and polymyxins) against three bacterial pathogens (methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Klebsiella pneumoniae). Sixteen compounds suppressed β-lactam resistance in MRSA, five of which effected a 16-fold reduction in the oxacillin minimum inhibitory concentration (MIC). Two natural products effectively suppressed aminoglycoside resistance in both of the Gram-negative species tested, and no hits were observed with macrolides. In contrast, a larger number of natural product adjuvants were identified when screening against colistin-resistant strains of A. baumannii and K. pneumoniae. Nine compounds reduced the colistin MIC to its breakpoint or lower (up to a 1024-fold reduction). Clorobiocin, novobiocin, and prodigiosin were most effective, reducing the colistin MIC in K. pneumoniae strain B9 to 2 μg/mL at concentrations as low as 0.625, 2.5, and 1.25 μM, respectively. Restored sensitivity to colistin with these compounds does not appear to coincide with known mechanisms of colistin resistance.
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Affiliation(s)
- Anne E. Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Karlie E. Cox
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Richard Smith
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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21
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Kathayat D, Antony L, Deblais L, Helmy YA, Scaria J, Rajashekara G. Small Molecule Adjuvants Potentiate Colistin Activity and Attenuate Resistance Development in Escherichia coli by Affecting pmrAB System. Infect Drug Resist 2020; 13:2205-2222. [PMID: 32764996 PMCID: PMC7360418 DOI: 10.2147/idr.s260766] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/16/2020] [Indexed: 12/22/2022] Open
Abstract
Background Colistin is one of the last-resort antibiotics to treat multi-drug resistant (MDR) Gram-negative bacterial infections in humans. Further, colistin has been also used to prevent and treat Enterobacteriaceae infections in food animals. However, chromosomal mutations and mobile colistin resistance (mcr) genes, which confer resistance to colistin, have been detected in bacterial isolates from food animals and humans worldwide; thus, limiting the use of colistin. Therefore, strategies that could aid in ameliorating colistin resistance are critically needed. Objective Investigate the adjuvant potential of novel small molecules (SMs) on colistin. Materials and Methods Previously, we identified 11 membrane-affecting SMs with bactericidal activity against avian pathogenic Escherichia coli (APEC). Here, we investigated the potentiation effect of those SMs on colistin using checkerboard assays and wax moth (Galleria mellonella) larval model. The impact of the SM combination on colistin resistance evolution was also investigated by analyzing whole genome sequences of APEC isolates passaged with colistin alone or in combination with SMs followed by quantitating pmrCAB and pmrH expression in those isolates. Results The SM combination synergistically reduced the minimum bactericidal concentration of colistin by at least 10-fold. In larvae, the SM combination increased the efficacy of colistin by two-fold with enhanced (>50%) survival and reduced (>4 logs) APEC load. Further, the SM combination decreased the frequency (5/6 to 1/6) of colistin resistance evolution and downregulated the pmrCAB and pmrH expression. Previously unknown mutations in pmrB (L14Q, T92P) and pmrA (A80V), which were predicted deleterious, were identified in the colistin-resistant (ColR) APEC isolates when passaged with colistin alone but not in combination with SMs. Our study also identified mutations in hypothetical and several phage-related proteins in ColR APEC isolates in concurrent with pmrAB mutations. Conclusion Our study identified two SMs (SM2 and SM3) that potentiated the colistin activity and attenuated the development of colistin resistance in APEC. These SMs can be developed as anti-evolution drugs that can slow down colistin resistance development.
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Affiliation(s)
- Dipak Kathayat
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Linto Antony
- Animal Disease Research and Diagnostic Laboratory, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA
| | - Loic Deblais
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Yosra A Helmy
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Joy Scaria
- Animal Disease Research and Diagnostic Laboratory, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
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22
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Kazi MI, Schargel RD, Boll JM. Generating Transposon Insertion Libraries in Gram-Negative Bacteria for High-Throughput Sequencing. J Vis Exp 2020. [PMID: 32716393 DOI: 10.3791/61612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Transposon sequencing (Tn-seq) is a powerful method that combines transposon mutagenesis and massive parallel sequencing to identify genes and pathways that contribute to bacterial fitness under a wide range of environmental conditions. Tn-seq applications are extensive and have not only enabled examination of genotype-phenotype relationships at an organism level but also at the population, community and systems levels. Gram-negative bacteria are highly associated with antimicrobial resistance phenotypes, which has increased incidents of antibiotic treatment failure. Antimicrobial resistance is defined as bacterial growth in the presence of otherwise lethal antibiotics. The "last-line" antimicrobial colistin is used to treat Gram-negative bacterial infections. However, several Gram-negative pathogens, including Acinetobacter baumannii can develop colistin resistance through a range of molecular mechanisms, some of which were characterized using Tn-seq. Furthermore, signal transduction pathways that regulate colistin resistance vary within Gram-negative bacteria. Here we propose an efficient method of transposon mutagenesis in A. baumannii that streamlines generation of a saturating transposon insertion library and amplicon library construction by eliminating the need for restriction enzymes, adapter ligation, and gel purification. The methods described herein will enable in-depth analysis of molecular determinants that contribute to A. baumannii fitness when challenged with colistin. The protocol is also applicable to other Gram-negative ESKAPE pathogens, which are primarily associated with drug resistant hospital-acquired infections.
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Affiliation(s)
- Misha I Kazi
- Department of Biology, University of Texas at Arlington
| | | | - Joseph M Boll
- Department of Biology, University of Texas at Arlington;
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23
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Barker WT, Jania LA, Melander RJ, Koller BH, Melander C. Eukaryotic phosphatase inhibitors enhance colistin efficacy in gram-negative bacteria. Chem Biol Drug Des 2020; 96:1180-1186. [PMID: 32562384 DOI: 10.1111/cbdd.13735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 04/26/2020] [Indexed: 12/12/2022]
Abstract
The mounting threat of multi-drug-resistant (MDR) bacteria places a tremendous strain on the antimicrobial clinical arsenal, forcing physicians to revert to near-obsolete antibiotics to treat otherwise intractable infections. Antibiotic adjuvant therapy has emerged as a viable alternative to the development of novel antimicrobial agents. This method uses combinations of an existing antibiotic and a non-antimicrobial small molecule, where the combination either breaks drug resistance or further potentiates antibiotic activity. Through a high-content screen of eukaryotic kinase inhibitors, our group previously identified two highly potent adjuvants that synergize with colistin, a cyclic, polycationic antimicrobial peptide that serves as a drug of last resort for the treatment of MDR Gram-negative bacterial infections. Cell signaling proteins implicated in colistin resistance mechanisms display both kinase and phosphatase activities. Herein, we explore the potential for eukaryotic phosphatase inhibitors to be repurposed as colistin adjuvants. From a panel of 48 unique structures, we discovered that the natural product kuwanon G breaks colistin resistance, while the non-antimicrobial macrolide ascomycin potentiates colistin in polymyxin-susceptible bacteria.
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Affiliation(s)
- William T Barker
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Leigh A Jania
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Beverly H Koller
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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Tsai CN, MacNair CR, Cao MPT, Perry JN, Magolan J, Brown ED, Coombes BK. Targeting Two-Component Systems Uncovers a Small-Molecule Inhibitor of Salmonella Virulence. Cell Chem Biol 2020; 27:793-805.e7. [PMID: 32413287 DOI: 10.1016/j.chembiol.2020.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/27/2020] [Accepted: 04/06/2020] [Indexed: 12/27/2022]
Abstract
Salmonella serovars are leading causes of gastrointestinal disease and have become increasingly resistant to fluoroquinolone and cephalosporin antibiotics. Overcoming this healthcare crisis requires new approaches in antibiotic discovery and the identification of unique bacterial targets. In this work, we describe a chemical genomics approach to identify inhibitors of Salmonella virulence. From a cell-based, promoter reporter screen of ∼50,000 small molecules, we identified dephostatin as a non-antibiotic compound that inhibits intracellular virulence factors and polymyxin resistance genes. Dephostatin disrupts signaling through both the SsrA-SsrB and PmrB-PmrA two-component regulatory systems and restores sensitivity to the last-resort antibiotic, colistin. Cell-based experiments and mouse models of infection demonstrate that dephostatin attenuates Salmonella virulence in vitro and in vivo, suggesting that perturbing regulatory networks is a promising strategy for the development of anti-infectives.
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Affiliation(s)
- Caressa N Tsai
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Craig R MacNair
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - My P T Cao
- Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada; Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Jordyn N Perry
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Jakob Magolan
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada; Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Eric D Brown
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Brian K Coombes
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada; Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4L8, Canada.
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25
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Simpson BW, Trent MS. Pushing the envelope: LPS modifications and their consequences. Nat Rev Microbiol 2020; 17:403-416. [PMID: 31142822 DOI: 10.1038/s41579-019-0201-x] [Citation(s) in RCA: 236] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The defining feature of the Gram-negative cell envelope is the presence of two cellular membranes, with the specialized glycolipid lipopolysaccharide (LPS) exclusively found on the surface of the outer membrane. The surface layer of LPS contributes to the stringent permeability properties of the outer membrane, which is particularly resistant to permeation of many toxic compounds, including antibiotics. As a common surface antigen, LPS is recognized by host immune cells, which mount defences to clear pathogenic bacteria. To alter properties of the outer membrane or evade the host immune response, Gram-negative bacteria chemically modify LPS in a wide variety of ways. Here, we review key features and physiological consequences of LPS biogenesis and modifications.
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Affiliation(s)
- Brent W Simpson
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA. .,Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA. .,Department of Microbiology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA.
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26
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A Whole-Cell Screen Identifies Small Bioactives That Synergize with Polymyxin and Exhibit Antimicrobial Activities against Multidrug-Resistant Bacteria. Antimicrob Agents Chemother 2020; 64:AAC.01677-19. [PMID: 31844003 DOI: 10.1128/aac.01677-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/05/2019] [Indexed: 12/19/2022] Open
Abstract
The threat of diminished antibiotic discovery has global health care in crisis. In the United States, it is estimated each year that over 2 million bacterial infections are resistant to first-line antibiotic treatments and cost in excess of 20 billion dollars. Many of these cases result from infection with the ESKAPE pathogens ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species), which are multidrug-resistant bacteria that often cause community- and hospital-acquired infections in both healthy and immunocompromised patients. Physicians have turned to last-resort antibiotics like polymyxins to tackle these pathogens, and as a consequence, polymyxin resistance has emerged and is spreading. Barring the discovery of new antibiotics, another route to successfully mitigate polymyxin resistance is to identify compounds that can complement the existing arsenal of antibiotics. We recently designed and performed a large-scale robotic screen to identify 43 bioactive compounds that act synergistically with polymyxin B to inhibit the growth of polymyxin-resistant Escherichia coli Of these 43 compounds, 5 lead compounds were identified and characterized using various Gram-negative bacterial organisms to better assess their synergistic activity with polymyxin. Several of these compounds reduce polymyxin to an MIC of <2 μg/ml against polymyxin-resistant and polymyxin-heteroresistant Gram-negative pathogens. Likewise, four of these compounds exhibit antimicrobial activity against Gram-positive bacteria, one of which rapidly eradicated methicillin-resistant Staphylococcus aureus We present multiple first-generation (i.e., not yet optimized) compounds that warrant further investigation and optimization, since they can act both synergistically with polymyxin and also as lone antimicrobials for combating ESKAPE pathogens.
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27
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Konai MM, Haldar J. Lysine-Based Small Molecule Sensitizes Rifampicin and Tetracycline against Multidrug-Resistant Acinetobacter baumannii and Pseudomonas aeruginosa. ACS Infect Dis 2020; 6:91-99. [PMID: 31646866 DOI: 10.1021/acsinfecdis.9b00221] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The priority pathogen list published by the World Health Organization (WHO) has categorized carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa as the top two critical pathogens, and hence, the development of novel antibacterial strategies to tackle such bacteria is highly necessary. Toward this aim, herein we report the efficacy of the combination of a lysine-based membrane-active small molecule, D-LANA-14 (d-lysine conjugated aliphatic norspermidine analogue bearing tetradecanoyl chain) and the obsolete/inactive antibiotics (such as tetracycline and rifampicin) to combat these superbugs. The combination of D-LANA-14 and the antibiotics tetracycline or rifampicin showed not only synergistic activity against growing planktonic cells of meropenem-resistant A. baumannii and P. aeruginosa clinical isolates but was also able to disrupt their established biofilms. More importantly, this synergistic effect was retained under the in vivo scenario, wherein the combination showed excellent efficacy in mice model of burn-wound infection with a drastic reduction of bacterial burden. A combined treatment of D-LANA-14 (40 mg/kg) and rifampicin (40 mg/kg) showed 4.9 log and 4.0 log reduction in A. baumannii and P. aeruginosa viability, respectively. On the contrary, individual treatment of D-LANA-14 decreased bacterial burden by 2.3 log (A. baumannii) and 1.3 log (P. aeruginosa) and rifampicin reduced about 3.0 log (A. baumannii) and 1.6 log (P. aeruginosa). Owing to the membrane-active nature imparted by D-LANA-14, bacteria could not develop resistance against the combined treatment, whereas a high-level of resistance development was observed against the last resort Gram-negative antibiotic, colistin. Taken together, the results therefore indicate a great potential of this novel combination to be developed as therapeutic regimen to combat infections caused by critical Gram-negative pathogens.
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Affiliation(s)
- Mohini Mohan Konai
- Antimicrobial Research Laboratory, New Chemistry Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, Karnataka, India
| | - Jayanta Haldar
- Antimicrobial Research Laboratory, New Chemistry Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru 560064, Karnataka, India
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Barker WT, Nemeth AM, Brackett SM, Basak AK, Chandler CE, Jania LA, Zuercher WJ, Melander RJ, Koller BH, Ernst RK, Melander C. Repurposing Eukaryotic Kinase Inhibitors as Colistin Adjuvants in Gram-Negative Bacteria. ACS Infect Dis 2019; 5:1764-1771. [PMID: 31434474 DOI: 10.1021/acsinfecdis.9b00212] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Kinase inhibitors comprise a diverse cohort of chemical scaffolds that are active in multiple biological systems. Currently, thousands of eukaryotic kinase inhibitors are commercially available, have well-characterized targets, and often carry pharmaceutically favorable toxicity profiles. Recently, our group disclosed that derivatives of the natural product meridianin D, a known inhibitor of eukaryotic kinases, modulated behaviors of both Gram-positive and Gram-negative bacteria. Herein, we expand our exploration of kinase inhibitors in Gram-negative bacilli utilizing three commercially available kinase inhibitor libraries and, ultimately, identify two chemical structures that potentiate colistin (polymyxin E) in multiple strains. We report IMD-0354, an inhibitor of IKK-β, as a markedly effective adjuvant in colistin-resistant bacteria and also describe AR-12 (OSU-03012), an inhibitor of pyruvate dehydrogenase kinase-1 (PDK-1), as a potentiator in colistin-sensitive strains. This report comprises the first description of the novel cross-reactivity of these molecules.
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Affiliation(s)
- William T. Barker
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
| | - Ansley M. Nemeth
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
| | - Sara M. Brackett
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
| | - Akash K. Basak
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
| | - Courtney E. Chandler
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, 650 W. Baltimore Street, Baltimore, Maryland 21201, United States
| | - Leigh A. Jania
- Department of Genetics, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, North Carolina 27599, United States
| | - William J. Zuercher
- Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, North Carolina 27599, United States
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
| | - Beverly H. Koller
- Department of Genetics, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, North Carolina 27599, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, 650 W. Baltimore Street, Baltimore, Maryland 21201, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, 240 McCourtney Hall, Notre Dame, Indiana 46556, United States
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29
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Dissecting Colistin Resistance Mechanisms in Extensively Drug-Resistant Acinetobacter baumannii Clinical Isolates. mBio 2019; 10:mBio.01083-19. [PMID: 31311879 PMCID: PMC6635527 DOI: 10.1128/mbio.01083-19] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The discovery of antibiotics revolutionized modern medicine and enabled us to cure previously deadly bacterial infections. However, a progressive increase in antibiotic resistance rates is a major and global threat for our health care system. Colistin represents one of our last-resort antibiotics that is still active against most Gram-negative bacterial pathogens, but increasing resistance is reported worldwide, in particular due to the plasmid-encoded protein MCR-1 present in pathogens such as Escherichia coli and Klebsiella pneumoniae. Here, we showed that colistin resistance in A. baumannii, a top-priority pathogen causing deadly nosocomial infections, is mediated through different avenues that result in increased activity of homologous phosphoethanolamine (PetN) transferases. Considering that MCR-1 is also a PetN transferase, our findings indicate that PetN transferases might be the Achilles heel of superbugs and that direct targeting of them may have the potential to preserve the activity of polymyxin antibiotics. Nosocomial infections with Acinetobacter baumannii are a global problem in intensive care units with high mortality rates. Increasing resistance to first- and second-line antibiotics has forced the use of colistin as last-resort treatment, and increasing development of colistin resistance in A. baumannii has been reported. We evaluated the transcriptional regulator PmrA as potential drug target to restore colistin efficacy in A. baumannii. Deletion of pmrA restored colistin susceptibility in 10 of the 12 extensively drug-resistant A. baumannii clinical isolates studied, indicating the importance of PmrA in the drug resistance phenotype. However, two strains remained highly resistant, indicating that PmrA-mediated overexpression of the phosphoethanolamine (PetN) transferase PmrC is not the exclusive colistin resistance mechanism in A. baumannii. A detailed genetic characterization revealed a new colistin resistance mechanism mediated by genetic integration of the insertion element ISAbaI upstream of the PmrC homolog EptA (93% identity), leading to its overexpression. We found that eptA was ubiquitously present in clinical strains belonging to the international clone 2, and ISAbaI integration upstream of eptA was required to mediate the colistin-resistant phenotype. In addition, we found a duplicated ISAbaI-eptA cassette in one isolate, indicating that this colistin resistance determinant may be embedded in a mobile genetic element. Our data disprove PmrA as a drug target for adjuvant therapy but highlight the importance of PetN transferase-mediated colistin resistance in clinical strains. We suggest that direct targeting of the homologous PetN transferases PmrC/EptA may have the potential to overcome colistin resistance in A. baumannii.
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30
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Krishnamurthy M, Lemmon MM, Falcinelli EM, Sandy RA, Dootz JN, Mott TM, Rajamani S, Schaecher KE, Duplantier AJ, Panchal RG. Enhancing the antibacterial activity of polymyxins using a nonantibiotic drug. Infect Drug Resist 2019; 12:1393-1405. [PMID: 31239720 PMCID: PMC6555264 DOI: 10.2147/idr.s196874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/06/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose: The rapid emergence of multidrug-resistant (MDR) bacteria and the lack of new therapies to eliminate them poses a major threat to global health. With the alarming rise in antimicrobial resistance (AMR), focus has now shifted to the use of the polymyxin class of antibiotics as the last line of defense for treatment of Gram-negative infections. Unfortunately, the growing resistance of bacteria against polymyxins is threatening the treatment of MDR infections, necessitating the need for novel strategies. The objective of this study was to determine if combination of polymyxin (polymyxin B or colistin) with a nonantibiotic small molecule AR-12, a celecoxib derivative that is devoid of cyclooxygenase 2 (COX-2) inhibitory activities, can be an effective strategy against polymyxin-resistant MDR bacteria. Methods: Growth inhibition studies, time-kill assays and permeability assays were conducted to investigate the effect of AR-12 on the antibacterial activity of polymyxins. Results: Growth studies were performed on a panel of polymyxin-resistant MDR strains using the combination of AR-12 with either colistin or polymyxin B. The combination treatment had no effect on strains that have inherent polymyxin resistance; however, AR-12 was effective in lowering the minimal inhibitory concentration (MIC) of polymyxins by 4–60-fold in several strains that had acquired polymyxin resistance. Time-kill assays using the combination of AR-12 and colistin with select MDR strains suggest rapid killing and bactericidal activity, while the permeability assays using fluorescently labeled dansylated polymyxin and 1-N-phenylnaphthylamine (NPN) in these MDR strains suggest that AR-12 can potentiate the antibacterial activity of polymyxins by possibly altering the bacterial outer membrane via modification of lipopolysaccharide and thereby improving the uptake of polymyxins. Conclusion: Our studies indicate that the combination of AR-12 and polymyxin is effective in targeting select Gram-negative bacteria that have acquired polymyxin resistance. Further understanding of the mechanism of action of AR-12 will provide new avenues for developing narrow-spectrum antibacterials to target select Gram-negative MDR bacteria. Importantly, our studies show that the use of nonantibiotic small molecules in combination with polymyxins is an attractive strategy to counter the growing resistance of bacteria to polymyxins.
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Affiliation(s)
- Malathy Krishnamurthy
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Margaret M Lemmon
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Evan M Falcinelli
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Reuel A Sandy
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Jennifer N Dootz
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Tiffany M Mott
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Sathish Rajamani
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA.,General Dynamics Information Technology, Frederick, MD, USA
| | - Kurt E Schaecher
- Department of Pathology, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Allen J Duplantier
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA.,Cherokee Nation Assurance, Frederick, MD, USA
| | - Rekha G Panchal
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
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31
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Minrovic BM, Hubble VB, Barker WT, Jania LA, Melander RJ, Koller BH, Melander C. Second-Generation Tryptamine Derivatives Potently Sensitize Colistin Resistant Bacteria to Colistin. ACS Med Chem Lett 2019; 10:828-833. [PMID: 31098007 DOI: 10.1021/acsmedchemlett.9b00135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 04/12/2019] [Indexed: 01/22/2023] Open
Abstract
Antibiotic resistance has significantly increased since the beginning of the 21st century. Currently, the polymyxin colistin is typically viewed as the antibiotic of last resort for the treatment of multidrug resistant Gram-negative bacterial infections. However, increased colistin usage has resulted in colistin-resistant bacterial isolates becoming more common. The recent dissemination of plasmid-borne colistin resistance genes (mcr 1-8) into the human pathogen pool is further threatening to render colistin therapy ineffective. New methods to combat antibiotic resistant pathogens are needed. Herein, the utilization of a colistin-adjuvant combination that is effective against colistin-resistant bacteria is described. At 5 μM, the lead adjuvant, which is nontoxic to the bacteria alone, increases colistin efficacy 32-fold against bacteria containing the mcr-1 gene and effects a 1024-fold increase in colistin efficacy against bacteria harboring chromosomally encoded colistin resistance determinants; these combinations lower the colistin minimum inhibitory concentration (MIC) to or below clinical breakpoint levels (≤2 μg/mL).
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Affiliation(s)
- Bradley M. Minrovic
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Veronica B. Hubble
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - William T. Barker
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Leigh A. Jania
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Beverly H. Koller
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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32
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Nguyen TV, Minrovic BM, Melander RJ, Melander C. Identification of Anti-Mycobacterial Biofilm Agents Based on the 2-Aminoimidazole Scaffold. ChemMedChem 2019; 14:927-937. [PMID: 30834698 DOI: 10.1002/cmdc.201900033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/04/2019] [Indexed: 12/12/2022]
Abstract
Tuberculosis (TB) remains a significant global health problem for which new therapeutic options are sorely needed. The ability of the causative agent, Mycobacterium tuberculosis, to reside within host macrophages and form biofilm-like communities contributes to the persistent and drug-tolerant nature of the disease. Compounds that can prevent or reverse the biofilm-like phenotype have the potential to serve alongside TB antibiotics to overcome this tolerance, and decrease treatment duration. Using Mycobacterium smegmatis as a surrogate organism, we report the identification of two new 2-aminoimidazole compounds that inhibit and disperse mycobacterial biofilms, work synergistically with isoniazid and rifampicin to eradicate preformed M. smegmatis biofilms in vitro, are nontoxic toward Galleria mellonella, and exhibit stability in mouse plasma.
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Affiliation(s)
- T Vu Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Bradley M Minrovic
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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33
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Barker WT, Chandler CE, Melander RJ, Ernst RK, Melander C. Tryptamine derivatives disarm colistin resistance in polymyxin-resistant gram-negative bacteria. Bioorg Med Chem 2019; 27:1776-1788. [PMID: 30898435 DOI: 10.1016/j.bmc.2019.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 11/30/2022]
Abstract
The last three decades have seen a dwindling number of novel antibiotic classes approved for clinical use and a concurrent increase in levels of antibiotic resistance, necessitating alternative methods to combat the rise of multi-drug resistant bacteria. A promising strategy employs antibiotic adjuvants, non-toxic molecules that disarm antibiotic resistance. When co-dosed with antibiotics, these compounds restore antibiotic efficacy in drug-resistant strains. Herein we identify derivatives of tryptamine, a ubiquitous biochemical scaffold containing an indole ring system, capable of disarming colistin resistance in the Gram-negative bacterial pathogens Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli while having no inherent bacterial toxicity. Resistance was overcome in strains carrying endogenous chromosomally-encoded colistin resistance machinery, as well as resistance conferred by the mobile colistin resistance-1 (mcr-1) plasmid-borne gene. These compounds restore a colistin minimum inhibitory concentration (MIC) below the Clinical & Laboratory Sciences Institute (CLSI) breakpoint in all resistant strains.
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Affiliation(s)
- William T Barker
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Courtney E Chandler
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, MD 21201, USA
| | - Roberta J Melander
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, MD 21201, USA
| | - Christian Melander
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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34
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De Silva PM, Kumar A. Signal Transduction Proteins in Acinetobacter baumannii: Role in Antibiotic Resistance, Virulence, and Potential as Drug Targets. Front Microbiol 2019; 10:49. [PMID: 30761101 PMCID: PMC6363711 DOI: 10.3389/fmicb.2019.00049] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a notorious pathogen in health care settings around the world, primarily due to high resistance to antibiotics. A. baumannii also shows an impressive capability to adapt to harsh conditions in clinical settings, which contributes to its persistence in such conditions. Following their traditional role, the Two Component Systems (TCSs) present in A. baumannii play a crucial role in sensing and adapting to the changing environmental conditions. This provides A. baumannii with a greater chance of survival even in unfavorable conditions. Since all the TCSs characterized to date in A. baumannii play a role in its antibiotic resistance and virulence, understanding the underlying molecular mechanisms behind TCSs can help with a better understanding of the pathways that regulate these phenotypes. This can also guide efforts to target TCSs as novel drug targets. In this review, we discuss the roles of TCSs in A. baumannii, their molecular mechanisms, and most importantly, the potential of using small molecule inhibitors of TCSs as potential novel drug targets.
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Affiliation(s)
- P Malaka De Silva
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada.,Manitoba Chemosensory Biology Group, University of Manitoba, Winnipeg, MB, Canada
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35
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Minrovic BM, Jung D, Melander RJ, Melander C. New Class of Adjuvants Enables Lower Dosing of Colistin Against Acinetobacter baumannii. ACS Infect Dis 2018; 4:1368-1376. [PMID: 29890069 DOI: 10.1021/acsinfecdis.8b00103] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Antibiotic resistance has become increasingly prevalent over the past few decades, and this combined with a dearth in the development of new classes of antibiotics to treat multidrug resistant Gram-negative infections has led to a significant global health problem and the increased usage of colistin as the last resort antibiotic. Colistin, however, presents dose dependent toxicity in the clinic. One potential approach to combatting this problem is the use of an antibiotic adjuvant, a compound that is nontoxic to the bacteria that enhances the potency of colistin and ultimately allows for reducing dosing. Herein, we present a new urea-containing class of 2-aminoimidazole-based adjuvants that potentiates colistin activity against colistin-sensitive Acinetobacter baumannii. Lead compounds enabled 1000-fold reduction in the minimum inhibitory concentration of colistin in vitro and showed efficacy in a Galleria mellonella infection model, representing the first step toward validating the potential of employing these adjuvants to lower colistin dosage.
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Affiliation(s)
- Bradley M. Minrovic
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27607, United States
| | - David Jung
- Agile Sciences, Inc., 1791 Varsity Drive, Suite 150, Raleigh, North Carolina 27606, United States
| | - Roberta J. Melander
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27607, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27607, United States
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Xu D, Qi X, Li J, Han X, Wang J, Jiang Y, Tian Y, Wang Y. PzTAC and PzLAZY from a narrow-crown poplar contribute to regulation of branch angles. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2017; 118:571-578. [PMID: 28787659 DOI: 10.1016/j.plaphy.2017.07.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 05/18/2023]
Abstract
Plant architecture, as a basic element influenced by genetic and environmental factors, has an important effect on grain yield via light transmission in agroforestry systems. The molecular mechanism underlying control of branch angle, an important aspect of tree architecture, is not well understood in poplars. Here, we cloned two genes from Populus × zhaiguanheibaiyang (a narrow-crown poplar), designated PzTAC and PzLAZY, which were predicted to be members of the ITG gene family through sequence homology. Transcript levels of the homologous genes were estimated by reverse transcriptase quantitative PCR (RT-qPCR) in different organs of P. × zhaiguanheibaiyang and P. Deltoides 'Zhonglin2025' (a broad-crown poplar). TAC expression was mainly confined to the leaves and annual shoots, whereas LAZY was mainly expressed in the annual shoots and axillary buds. Beside, we detected the promoter expression patterns derived from the PzTAC and PzLAZY genes using the β-glucuronidase (GUS) reporter gene in transgenic Populus × euramericana 'Neva'. GUS activity driven by the PzTAC and PzLAZY promoters was detected in mature leaves, leaf axils and vascular tissues of roots. The PzTAC promoter was mainly active in leaf veins, whereas the PzLAZY promoter was mainly active in mesophyll cells and root tips. The average branch angle in transgenic 35S::PzTAC plants was larger than that of transgenic 35S::PzLAZY plants. The results provide strong evidence that the two genes affect the vascular tissues of transgenic plants to modify branch angles.
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Affiliation(s)
- Dong Xu
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
| | - Xiao Qi
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
| | - Jihong Li
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
| | - Xiaojiao Han
- Key Laboratory of Tree Breeding of Zhejiang Province, Research Institute of Subtropical of Forestry, Chinese Academy of Forestry, Hangzhou, Zhejiang, 311400, PR China.
| | - Jinnan Wang
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
| | - Yuezhong Jiang
- Forestry Science Academy of Shandong, Shandong Provincial Key Laboratory of Forest Tree Genetic Improvement, Ji'nan 250014, Shandong, PR China.
| | - Yanting Tian
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
| | - Yiwei Wang
- Key Laboratory of Agricultural Ecology and Environment, College of Forestry, Shandong Agricultural University, Tai'an, Shandong 271018, PR China.
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Uppu DSSM, Konai MM, Sarkar P, Samaddar S, Fensterseifer ICM, Farias-Junior C, Krishnamoorthy P, Shome BR, Franco OL, Haldar J. Membrane-active macromolecules kill antibiotic-tolerant bacteria and potentiate antibiotics towards Gram-negative bacteria. PLoS One 2017; 12:e0183263. [PMID: 28837596 PMCID: PMC5570306 DOI: 10.1371/journal.pone.0183263] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 08/01/2017] [Indexed: 12/11/2022] Open
Abstract
Chronic bacterial biofilms place a massive burden on healthcare due to the presence of antibiotic-tolerant dormant bacteria. Some of the conventional antibiotics such as erythromycin, vancomycin, linezolid, rifampicin etc. are inherently ineffective against Gram-negative bacteria, particularly in their biofilms. Here, we report membrane-active macromolecules that kill slow dividing stationary-phase and antibiotic tolerant cells of Gram-negative bacteria. More importantly, these molecules potentiate antibiotics (erythromycin and rifampicin) to biofilms of Gram-negative bacteria. These molecules eliminate planktonic bacteria that are liberated after dispersion of biofilms (dispersed cells). The membrane-active mechanism of these molecules forms the key for potentiating the established antibiotics. Further, we demonstrate that the combination of macromolecules and antibiotics significantly reduces bacterial burden in mouse burn and surgical wound infection models caused by Acinetobacter baumannii and Carbapenemase producing Klebsiella pneumoniae (KPC) clinical isolate respectively. Colistin, a well-known antibiotic targeting the lipopolysaccharide (LPS) of Gram-negative bacteria fails to kill antibiotic tolerant cells and dispersed cells (from biofilms) and bacteria develop resistance to it. On the contrary, these macromolecules prevent or delay the development of bacterial resistance to known antibiotics. Our findings emphasize the potential of targeting the bacterial membrane in antibiotic potentiation for disruption of biofilms and suggest a promising strategy towards developing therapies for topical treatment of Gram-negative infections.
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Affiliation(s)
- Divakara S. S. M. Uppu
- Chemical Biology & Medicinal Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Karnataka, India
| | - Mohini M. Konai
- Chemical Biology & Medicinal Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Karnataka, India
| | - Paramita Sarkar
- Chemical Biology & Medicinal Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Karnataka, India
| | - Sandip Samaddar
- Chemical Biology & Medicinal Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Karnataka, India
| | - Isabel C. M. Fensterseifer
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia UC, Brası´lia, Brazil
- Molecular Pathology Post-Graduate Program, University of Brasília, Brasília, Brazil
| | | | - Paramanandam Krishnamoorthy
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Bibek R. Shome
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Octávio L. Franco
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia UC, Brası´lia, Brazil
- Molecular Pathology Post-Graduate Program, University of Brasília, Brasília, Brazil
- S-inova Biotech, Pos-Graduação em Biotecnoloia, Universidade Catolica Dom Bosco, Campo Grande, Brazil
| | - Jayanta Haldar
- Chemical Biology & Medicinal Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, Karnataka, India
- * E-mail:
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Melander RJ, Melander C. The Challenge of Overcoming Antibiotic Resistance: An Adjuvant Approach? ACS Infect Dis 2017; 3:559-563. [PMID: 28548487 DOI: 10.1021/acsinfecdis.7b00071] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antibiotic resistance is one of the greatest current threats to human health, and without significant action we face the chilling prospect of a world without effective antibiotics. Although continued effort toward the development of new antibiotics, particularly those with novel mechanisms of action, remains crucial, this alone probably will not be enough to prevail, and it is imperative that additional approaches are also explored. One such approach is the identification of adjuvants that augment the activity of current antibiotics. This approach has the potential to render an antibiotic against which bacteria have developed resistance once again effective, to broaden the spectrum of an antibiotic, and to lower the required dose of an antibiotic. In this viewpoint we discuss some of the advantages and disadvantages of the use of adjuvants, and describe various approaches to their identification.
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Affiliation(s)
- Roberta J. Melander
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, United States
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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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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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Zhang X, Guo F, Shao H, Zheng X. Clinical translation of polymyxin-based combination therapy: Facts, challenges and future opportunities. J Infect 2016; 74:118-130. [PMID: 27998750 DOI: 10.1016/j.jinf.2016.11.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/18/2016] [Accepted: 11/27/2016] [Indexed: 10/20/2022]
Abstract
The emergence and spread of multidrug resistant Gram-negative bacteria has led to a resurgence in the clinical use of polymyxin antibiotics. However, the prevalence of polymyxin resistance is on the rise at an alarming rate, motivating the idea of combination therapy to sustain the revival of these "old" antibiotics. Although ample evidence in favor of combination therapy has emerged, it seems impracticable and confusing to find a promising combination from the diverse reports or gain adequate information on the efficacy and safety profile. With a stagnating discovery pipeline of novel antimicrobials, there is a clear need to fill the knowledge gaps in translating these basic research data to beneficial clinical practice. In this review, we examined the factors and ambiguities that stand as major hurdles in bringing polymyxin combination therapy to bedside care, highlighting the importance and urgency of incorporating translational research insights into areas of difficulty. We also discussed future research priorities that are essential to gather the necessary evidence and insights for promoting the best possible use of polymyxins in combination therapy.
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Affiliation(s)
- Xueli Zhang
- Department of Pharmacy, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China
| | - Fengmei Guo
- Department of Critical Care Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China
| | - Hua Shao
- Department of Pharmacy, Zhongda Hospital, School of Medicine, Southeast University, Nanjing 210009, China.
| | - Xiao Zheng
- State Key Laboratory of Natural Medicines, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China.
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43
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Melander RJ, Liu HB, Stephens MD, Bewley CA, Melander C. Marine sponge alkaloids as a source of anti-bacterial adjuvants. Bioorg Med Chem Lett 2016; 26:5863-5866. [PMID: 27876320 PMCID: PMC5776710 DOI: 10.1016/j.bmcl.2016.11.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 11/07/2016] [Accepted: 11/08/2016] [Indexed: 11/21/2022]
Abstract
Novel approaches that do not rely upon developing microbicidal compounds are sorely needed to combat multidrug resistant (MDR) bacteria. The potential of marine secondary metabolites to serve as a source of non-traditional anti-bacterial agents is demonstrated by showing that pyrrole-imidazole alkaloids inhibit biofilm formation and suppress antibiotic resistance.
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Affiliation(s)
- Roberta J. Melander
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8024, United States
| | - Hong-bing Liu
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, United States
| | - Matthew D. Stephens
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8024, United States
| | - Carole A. Bewley
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8024, United States
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Zhu Y, Cleaver L, Wang W, Podoll JD, Walls S, Jolly A, Wang X. Tetracyclic indolines as a novel class of β-lactam-selective resistance-modifying agent for MRSA. Eur J Med Chem 2016; 125:130-142. [PMID: 27657810 DOI: 10.1016/j.ejmech.2016.09.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/04/2016] [Accepted: 09/09/2016] [Indexed: 01/11/2023]
Abstract
Antibiotic-resistant bacterial infections have seen a marked increase in recent years, while antibiotic discovery has waned. Resistance-modifying agents (RMA) offer an intriguing alternative strategy to fight against resistant bacteria. Here we report the discovery, antibiotic profiling, and structure-activity relationships of a novel class of RMAs, tetracyclic indolines. These selectively potentiate β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) without antibacterial or β-lactamase inhibitory activity on their own. The most potent analogue, 6a, showed strong potentiation of amoxicillin/clavulanic acid in a variety of hospital-acquired and community-acquired MRSA strains with low mammalian toxicity. These compounds may be further developed to extend the clinic life span of β-lactam antibiotics.
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Affiliation(s)
- Yugen Zhu
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Lakota Cleaver
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Wei Wang
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Jessica D Podoll
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Shane Walls
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Austin Jolly
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Xiang Wang
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA.
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Second Generation Modifiers of Colistin Resistance Show Enhanced Activity and Lower Inherent Toxicity. Tetrahedron 2016; 72:3549-3553. [PMID: 27429479 DOI: 10.1016/j.tet.2015.09.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We recently reported a 2-aminoimidazole-based antibiotic adjuvant that reverses colistin resistance in two species of Gram-negative bacteria. Mechanistic studies in Acinetobacter baumannii demonstrated that this compound downregulated the PmrAB two-component system and abolished a lipid A modification that is required for colistin resistance. We now report the synthesis and evaluation of two separate libraries of substituted 2-aminoimidazole analogues based on this parent compound. From these libraries, a new small molecule was identified that lowers the minimum inhibitory concentration of colistin by up to 32-fold greater than the parent compound while also displaying less inherent bacterial effect, thereby minimizing the likelihood of resistance evolution.
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46
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Molecular mechanisms of membrane targeting antibiotics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:980-7. [DOI: 10.1016/j.bbamem.2015.10.018] [Citation(s) in RCA: 270] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/07/2015] [Accepted: 10/23/2015] [Indexed: 01/17/2023]
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Smani Y, Pachón-Ibáñez ME, Pachón J. New molecules and adjuvants in the treatment of infections by Acinetobacter baumannii. Expert Opin Pharmacother 2016; 17:1207-14. [PMID: 27067283 DOI: 10.1080/14656566.2016.1176144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION The current problems of the treatment of infections by Acinetobacter baumannii are linked with the increase of multidrug- and extensive-drug resistance and the lack of development of new antimicrobial drugs for Gram-negative bacilli. For these reasons, new alternatives for the treatment and control of severe infections by A. baumannii are necessary. Several studies have reported the effect of adjuvants to restore the efficacy of existing antimicrobial agents. AREAS COVERED In the present review, the authors describe the main results in the development of adjuvant drugs as well as new data on antimicrobial peptides, in monotherapy or in combination therapy with existing antimicrobial agents, which have shown promising preclinical results in vitro and in vivo. EXPERT OPINION The preclinical evaluation of adjuvants and antimicrobial peptides, in monotherapy or in combination therapy, for A. baumannii infections has shown promising results. However, caution is needed and further extensive in vivo studies and clinical trials have to be performed to confirm the potential use of these adjuvants as true therapeutic alternatives.
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Affiliation(s)
- Younes Smani
- a Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine , Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville , Seville , Spain
| | - María Eugenia Pachón-Ibáñez
- a Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine , Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville , Seville , Spain
| | - Jerónimo Pachón
- a Clinical Unit of Infectious Diseases, Microbiology, and Preventive Medicine , Institute of Biomedicine of Seville (IBiS), University Hospital Virgen del Rocío/CSIC/University of Seville , Seville , Spain
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48
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Feldmann EA, Cavanagh J. Teaching old drugs new tricks: Addressing resistance in Francisella. Virulence 2016; 6:414-6. [PMID: 26055396 DOI: 10.1080/21505594.2015.1053689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Erik A Feldmann
- a Department of Molecular and Structural Biochemistry; North Carolina State University ; Raleigh , NC , USA
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49
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Uppu DSSM, Samaddar S, Ghosh C, Paramanandham K, Shome BR, Haldar J. Amide side chain amphiphilic polymers disrupt surface established bacterial bio-films and protect mice from chronic Acinetobacter baumannii infection. Biomaterials 2016; 74:131-43. [DOI: 10.1016/j.biomaterials.2015.09.042] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/24/2015] [Accepted: 09/26/2015] [Indexed: 02/04/2023]
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50
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References. Antibiotics (Basel) 2015. [DOI: 10.1128/9781555819316.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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