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Chang H, Clemens S, Gao P, Li Q, Zhao H, Wang L, Zhang J, Zhou P, Johnsson K, Wang L. Fluorogenic Rhodamine-Based Chemigenetic Biosensor for Monitoring Cellular NADPH Dynamics. J Am Chem Soc 2024. [PMID: 39037873 DOI: 10.1021/jacs.3c13137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Ratiometric biosensors employing Förster Resonance Energy Transfer (FRET) enable the real-time tracking of metabolite dynamics. Here, we introduce an approach for generating a FRET-based biosensor in which changes in apparent FRET efficiency rely on the analyte-controlled fluorogenicity of a rhodamine rather than the commonly used distance change between donor-acceptor fluorophores. Our fluorogenic, rhodamine-based, chemigenetic biosensor (FOCS) relies on a synthetic, protein-tethered FRET probe, in which the rhodamine acting as the FRET acceptor switches in an analyte-dependent manner from a dark to a fluorescent state. This allows ratiometric sensing of the analyte concentration. We use this approach to generate a chemigenetic biosensor for nicotinamide adenine dinucleotide phosphate (NADPH). FOCS-NADPH exhibits a rapid and reversible response toward NAPDH with a good dynamic range, selectivity, and pH insensitivity. FOCS-NADPH allows real-time monitoring of cytosolic NADPH fluctuations in live cells during oxidative stress or after drug exposure. We furthermore used FOCS-NADPH to investigate NADPH homeostasis regulation through the pentose phosphate pathway of glucose metabolism. FOCS-NADPH is a powerful tool for studying NADPH metabolism and serves as a blueprint for the development of future fluorescent biosensors.
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Affiliation(s)
- Huimin Chang
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Simon Clemens
- Department of Chemical Biology, Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg D-69120, Germany
| | - Pingting Gao
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Quanlin Li
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Hanqing Zhao
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Lehua Wang
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Jingye Zhang
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Pinghong Zhou
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
| | - Kai Johnsson
- Department of Chemical Biology, Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg D-69120, Germany
- Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Lu Wang
- Key Laboratory of Smart Drug Delivery Ministry of Education, School of Pharmacy, Endoscopy Center and Endoscopy Research Institute, Zhongshan Hospital, Fudan University, Zhangheng Road 826, Shanghai 201203, China
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2
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Gütgemann F, Heuvelink A, Müller A, Churin Y, Buter R, Jung A, Feberwee A, Wiegel J, Kumm F, Braun AS, Yue M, Soriano-Vargas E, Swanepoel S, Botteldoorn N, Kirchner M, Kehrenberg C. Recommendation of a standardized broth microdilution method for antimicrobial susceptibility testing of Avibacterium paragallinarum and resistance monitoring. J Clin Microbiol 2024; 62:e0101123. [PMID: 38363142 PMCID: PMC10935639 DOI: 10.1128/jcm.01011-23] [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] [Received: 08/04/2023] [Accepted: 12/11/2023] [Indexed: 02/17/2024] Open
Abstract
This study aimed to develop a method for standardized broth microdilution antimicrobial susceptibility testing (AST) of Avibacterium (Av.) paragallinarum, the causative agent of infectious coryza in chickens. For this, a total of 83 Av. paragallinarum isolates and strains were collected from 15 countries. To select unrelated isolates for method validation steps, macrorestriction analyses were performed with 15 Av. paragallinarum. The visible growth of Av. paragallinarum was examined in six broth media and growth curves were compiled. In Veterinary Fastidious Medium and cation-adjusted Mueller-Hinton broth (CAMHB) + 1% chicken serum + 0.0025% NADH (CAMHB + CS + NADH), visible growth of all isolates was detected and both media allowed adequate bacterial growth. Due to the better readability of Av. paragallinarum growth in microtiter plates, CAMHB + CS + NADH was chosen for AST. Repetitions of MIC testing with five epidemiologically unrelated isolates using a panel of 24 antimicrobial agents resulted in high essential MIC agreements of 96%-100% after 48-h incubation at 35 ± 2°C. Hence, the remaining 78 Av. paragallinarum were tested and demonstrated easily readable MICs with the proposed method. Differences in MICs were detected between isolates from different continents, with isolates from Africa showing lower MICs compared to isolates from America and Europe, which more often showed elevated MICs of aminoglycosides, quinolones, tetracyclines, and/or trimethoprim/sulfamethoxazole. PCR analyses of isolates used for method development revealed that isolates with elevated MICs of tetracyclines harbored the tetracycline resistance gene tet(B) but none of the other tested resistance genes were detected. Therefore, whole-genome sequencing data from 62 Av. paragallinarum were analyzed and revealed the presence of sequences showing nucleotide sequence identity to the genes aph(6)-Id, aph(3″)-Ib, blaTEM-1B, catA2, sul2, tet(B), tet(H), and mcr-like. Overall, the proposed method using CAMHB + CS + NADH for susceptibility testing with 48-h incubation time at 35 ± 2°C in ambient air was shown to be suitable for Av. paragallinarum. Due to a variety of resistance genes detected, the development of clinical breakpoints is highly recommended. IMPORTANCE Avibacterium paragallinarum is an important pathogen in veterinary medicine that causes infectious coryza in chickens. Since antibiotics are often used for treatment and resistance of the pathogen is known, targeted therapy should be given after resistance testing of the pathogen. Unfortunately, there is currently no accepted method in standards that allows susceptibility testing of this fastidious pathogen. Therefore, we have worked out a method that allows harmonized susceptibility testing of the pathogen. The method meets the requirements of the CLSI and could be used by diagnostic laboratories.
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Affiliation(s)
- Franziska Gütgemann
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
| | | | - Anja Müller
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Yury Churin
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
| | | | - Arne Jung
- Clinic for Poultry, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | | | | | - Franziska Kumm
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Ann Sophie Braun
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
| | - Min Yue
- Hainan Institute of Zhejiang University, Sanya, China
- Department of Veterinary Medicine, Institute of Preventive Veterinary Science, Zhejiang University College of Animal Sciences, Hangzhou, China
| | - Edgardo Soriano-Vargas
- Centro de Investigación y Estudios Avanzados en Salud Animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma del Estado de México, Toluca, Mexico
| | | | | | - Miranda Kirchner
- Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom
| | - Corinna Kehrenberg
- Institute for Veterinary Food Science, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Giessen, Germany
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3
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Faleye OS, Boya BR, Lee JH, Choi I, Lee J. Halogenated Antimicrobial Agents to Combat Drug-Resistant Pathogens. Pharmacol Rev 2023; 76:90-141. [PMID: 37845080 DOI: 10.1124/pharmrev.123.000863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 08/07/2023] [Accepted: 09/29/2023] [Indexed: 10/18/2023] Open
Abstract
Antimicrobial resistance presents us with a potential global crisis as it undermines the abilities of conventional antibiotics to combat pathogenic microbes. The history of antimicrobial agents is replete with examples of scaffolds containing halogens. In this review, we discuss the impacts of halogen atoms in various antibiotic types and antimicrobial scaffolds and their modes of action, structure-activity relationships, and the contributions of halogen atoms in antimicrobial activity and drug resistance. Other halogenated molecules, including carbohydrates, peptides, lipids, and polymeric complexes, are also reviewed, and the effects of halogenated scaffolds on pharmacokinetics, pharmacodynamics, and factors affecting antimicrobial and antivirulence activities are presented. Furthermore, the potential of halogenation to circumvent antimicrobial resistance and rejuvenate impotent antibiotics is addressed. This review provides an overview of the significance of halogenation, the abilities of halogens to interact in biomolecular settings and enhance pharmacological properties, and their potential therapeutic usages in preventing a postantibiotic era. SIGNIFICANCE STATEMENT: Antimicrobial resistance and the increasing impotence of antibiotics are critical threats to global health. The roles and importance of halogen atoms in antimicrobial drug scaffolds have been established, but comparatively little is known of their pharmacological impacts on drug resistance and antivirulence activities. This review is the first to extensively evaluate the roles of halogen atoms in various antibiotic classes and pharmacological scaffolds and to provide an overview of their ability to overcome antimicrobial resistance.
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Affiliation(s)
- Olajide Sunday Faleye
- School of Chemical Engineering (O.S.F., B.R.B., J.-H.L., J.L.) and Department of Medical Biotechnology (I.C.), Yeungnam University, Gyeongsan, Republic of Korea
| | - Bharath Reddy Boya
- School of Chemical Engineering (O.S.F., B.R.B., J.-H.L., J.L.) and Department of Medical Biotechnology (I.C.), Yeungnam University, Gyeongsan, Republic of Korea
| | - Jin-Hyung Lee
- School of Chemical Engineering (O.S.F., B.R.B., J.-H.L., J.L.) and Department of Medical Biotechnology (I.C.), Yeungnam University, Gyeongsan, Republic of Korea
| | - Inho Choi
- School of Chemical Engineering (O.S.F., B.R.B., J.-H.L., J.L.) and Department of Medical Biotechnology (I.C.), Yeungnam University, Gyeongsan, Republic of Korea
| | - Jintae Lee
- School of Chemical Engineering (O.S.F., B.R.B., J.-H.L., J.L.) and Department of Medical Biotechnology (I.C.), Yeungnam University, Gyeongsan, Republic of Korea
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4
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Fanti RC, Vasconcelos SNS, Catta-Preta CMC, Sullivan JR, Riboldi GP, Dos Reis CV, Ramos PZ, Edwards AM, Behr MA, Couñago RM. A Target Engagement Assay to Assess Uptake, Potency, and Retention of Antibiotics in Living Bacteria. ACS Infect Dis 2022; 8:1449-1467. [PMID: 35815896 DOI: 10.1021/acsinfecdis.2c00073] [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: 11/28/2022]
Abstract
New antibiotics are urgently needed to counter the emergence of antimicrobial-resistant pathogenic bacteria. A major challenge in antibiotic drug discovery is to turn potent biochemical inhibitors of essential bacterial components into effective antimicrobials. This difficulty is underpinned by a lack of methods to investigate the physicochemical properties needed for candidate antibiotics to permeate the bacterial cell envelope and avoid clearance by the action of bacterial efflux pumps. To address these issues, here we used a target engagement assay to measure the equilibrium and kinetic binding parameters of antibiotics targeting dihydrofolate reductase (DHFR) in live bacteria. We also used this assay to identify novel DHFR ligands having antimicrobial activity. We validated this approach using the Gram-negative bacteria Escherichia coli and the emerging human pathogen Mycobacterium abscessus. We expect the use of target engagement assays in bacteria to expedite the discovery and progression of novel, cell-permeable antibiotics with on-target activity.
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Affiliation(s)
- Rebeka C Fanti
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil.,Post-Graduate Program in Genetics and Molecular Biology (PGBM), UNICAMP, Campinas 13083-970, Brazil
| | - Stanley N S Vasconcelos
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil
| | - Carolina M C Catta-Preta
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil
| | - Jaryd R Sullivan
- Department of Microbiology & Immunology, McGill University, Montréal H3A 2B4, Canada.,Infectious Diseases and Immunity in Global Health Program, Research Institute of the McGill University Health Centre, Montréal H4A 3J1, Canada.,McGill International TB Centre, Montréal H4A 3S5, Canada
| | - Gustavo P Riboldi
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil
| | - Caio V Dos Reis
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil
| | - Priscila Z Ramos
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil
| | - Aled M Edwards
- Structural Genomics Consortium, 101 College Street, Toronto M5G 1L7, Canada
| | - Marcel A Behr
- Department of Microbiology & Immunology, McGill University, Montréal H3A 2B4, Canada.,Infectious Diseases and Immunity in Global Health Program, Research Institute of the McGill University Health Centre, Montréal H4A 3J1, Canada.,McGill International TB Centre, Montréal H4A 3S5, Canada.,Department of Medicine, McGill University Health Centre, Montréal H4A 3J1, Canada
| | - Rafael M Couñago
- Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas 13083-886, Brazil.,Post-Graduate Program in Genetics and Molecular Biology (PGBM), UNICAMP, Campinas 13083-970, Brazil
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5
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Turner AK, Yasir M, Bastkowski S, Telatin A, Page A, Webber M, Charles I. Chemical biology-whole genome engineering datasets predict new antibacterial combinations. Microb Genom 2021; 7. [PMID: 34874820 PMCID: PMC8767339 DOI: 10.1099/mgen.0.000718] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Trimethoprim and sulfamethoxazole are used commonly together as cotrimoxazole for the treatment of urinary tract and other infections. The evolution of resistance to these and other antibacterials threatens therapeutic options for clinicians. We generated and analysed a chemical-biology-whole-genome data set to predict new targets for antibacterial combinations with trimethoprim and sulfamethoxazole. For this we used a large transposon mutant library in Escherichia coli BW25113 where an outward-transcribing inducible promoter was engineered into one end of the transposon. This approach allows regulated expression of adjacent genes in addition to gene inactivation at transposon insertion sites, a methodology that has been called TraDIS-Xpress. These chemical genomic data sets identified mechanisms for both reduced and increased susceptibility to trimethoprim and sulfamethoxazole. The data identified that over-expression of FolA reduced trimethoprim susceptibility, a known mechanism for reduced susceptibility. In addition, transposon insertions into the genes tdk, deoR, ybbC, hha, ldcA, wbbK and waaS increased susceptibility to trimethoprim and likewise for rsmH, fadR, ddlB, nlpI and prc with sulfamethoxazole, while insertions in ispD, uspC, minC, minD, yebK, truD and umpG increased susceptibility to both these antibiotics. Two of these genes’ products, Tdk and IspD, are inhibited by AZT and fosmidomycin respectively, antibiotics that are known to synergise with trimethoprim. Thus, the data identified two known targets and several new target candidates for the development of co-drugs that synergise with trimethoprim, sulfamethoxazole or cotrimoxazole. We demonstrate that the TraDIS-Xpress technology can be used to generate information-rich chemical-genomic data sets that can be used for antibacterial development.
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Affiliation(s)
- Arthur K Turner
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Muhammad Yasir
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Sarah Bastkowski
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Andrea Telatin
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
| | - Andrew Page
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK.,University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Mark Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK.,University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Ian Charles
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK.,University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
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6
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Ryser LT, Arias-Roth E, Perreten V, Irmler S, Bruggmann R. Genetic and Phenotypic Diversity of Morganella morganii Isolated From Cheese. Front Microbiol 2021; 12:738492. [PMID: 34867855 PMCID: PMC8638253 DOI: 10.3389/fmicb.2021.738492] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 10/13/2021] [Indexed: 01/02/2023] Open
Abstract
The bacterium Morganella morganii can produce the biogenic amines (BA) cadaverine, putrescine, and histamine in vitro and is responsible for high histamine concentrations in fish products. These BA can have toxic effects upon ingestion and are undesired in food. The purpose of this study was to characterize the phenotype and genotype of 11 M. morganii isolated from cheese in regard to the BA formation. In addition, we investigated the phylogeny, trehalose fermentation ability, and antibiotic resistance of the cheese isolates. To do so, we sequenced their genomes using both long and short read technologies. Due to the presence of the trehalose operon and the ability to ferment trehalose, the cheese isolates can be assigned to the subsp. sibonii. Comparative genomics with public available M. morganii genomes shows that the genomes of the cheese isolates cluster together with other subsp. sibonii genomes. All genomes between subsp. morganii and subsp. sibonii are separated by an average nucleotide identity (ANI) of less than 95.0%. Therefore, the subspecies could represent two distinct species. Nine of the strains decarboxylated lysine yielding cadaverine in vitro. This metabolic activity is linked to a previously unknown gene cluster comprising genes encoding a lysine-tRNA ligase (lysS), an HTH-transcriptional regulator (argP), a cadaverine-lysine antiporter (cadB), and a lysine decarboxylase (cadA). The formation of putrescine is linked to the speF gene encoding an ornithine decarboxylase. The gene is disrupted in five strains by an insertion sequence, and these strains only exhibit a weak putrescine production. Antimicrobial susceptibility profiling revealed that all cheese strains are resistant to tetracycline, chloramphenicol, tigecycline, colistin, and ampicillin. These phenotypes, except for colistin which is intrinsic, could be linked to antimicrobial resistance genes located on the chromosome.
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Affiliation(s)
- Lorenz Timo Ryser
- Interfaculty Bioinformatics Unit and Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland.,Agroscope, Bern, Switzerland
| | | | - Vincent Perreten
- Institute of Veterinary Bacteriology, University of Bern, Bern, Switzerland
| | | | - Rémy Bruggmann
- Interfaculty Bioinformatics Unit and Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
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7
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Patel V, Matange N. Adaptation and compensation in a bacterial gene regulatory network evolving under antibiotic selection. eLife 2021; 10:70931. [PMID: 34591012 PMCID: PMC8483737 DOI: 10.7554/elife.70931] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/22/2021] [Indexed: 12/28/2022] Open
Abstract
Gene regulatory networks allow organisms to generate coordinated responses to environmental challenges. In bacteria, regulatory networks are re-wired and re-purposed during evolution, though the relationship between selection pressures and evolutionary change is poorly understood. In this study, we discover that the early evolutionary response of Escherichia coli to the antibiotic trimethoprim involves derepression of PhoPQ signaling, an Mg2+-sensitive two-component system, by inactivation of the MgrB feedback-regulatory protein. We report that derepression of PhoPQ confers trimethoprim-tolerance to E. coli by hitherto unrecognized transcriptional upregulation of dihydrofolate reductase (DHFR), target of trimethoprim. As a result, mutations in mgrB precede and facilitate the evolution of drug resistance. Using laboratory evolution, genome sequencing, and mutation re-construction, we show that populations of E. coli challenged with trimethoprim are faced with the evolutionary ‘choice’ of transitioning from tolerant to resistant by mutations in DHFR, or compensating for the fitness costs of PhoPQ derepression by inactivating the RpoS sigma factor, itself a PhoPQ-target. Outcomes at this evolutionary branch-point are determined by the strength of antibiotic selection, such that high pressures favor resistance, while low pressures favor cost compensation. Our results relate evolutionary changes in bacterial gene regulatory networks to strength of selection and provide mechanistic evidence to substantiate this link.
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Affiliation(s)
- Vishwa Patel
- Dr. Vikram Sarabhai Institute of Cell and Molecular Biology, The Maharaja Sayajirao University of Baroda, Vadodara, India.,Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Nishad Matange
- Indian Institute of Science Education and Research (IISER), Pune, India
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8
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Sánchez-Osuna M, Cortés P, Llagostera M, Barbé J, Erill I. Exploration into the origins and mobilization of di-hydrofolate reductase genes and the emergence of clinical resistance to trimethoprim. Microb Genom 2020; 6:mgen000440. [PMID: 32969787 PMCID: PMC7725336 DOI: 10.1099/mgen.0.000440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/08/2020] [Indexed: 01/23/2023] Open
Abstract
Trimethoprim is a synthetic antibacterial agent that targets folate biosynthesis by competitively binding to the di-hydrofolate reductase enzyme (DHFR). Trimethoprim is often administered synergistically with sulfonamide, another chemotherapeutic agent targeting the di-hydropteroate synthase (DHPS) enzyme in the same pathway. Clinical resistance to both drugs is widespread and mediated by enzyme variants capable of performing their biological function without binding to these drugs. These mutant enzymes were assumed to have arisen after the discovery of these synthetic drugs, but recent work has shown that genes conferring resistance to sulfonamide were present in the bacterial pangenome millions of years ago. Here, we apply phylogenetics and comparative genomics methods to study the largest family of mobile trimethoprim-resistance genes (dfrA). We show that most of the dfrA genes identified to date map to two large clades that likely arose from independent mobilization events. In contrast to sulfonamide resistance (sul) genes, we find evidence of recurrent mobilization in dfrA genes. Phylogenetic evidence allows us to identify novel dfrA genes in the emerging pathogen Acinetobacter baumannii, and we confirm their resistance phenotype in vitro. We also identify a cluster of dfrA homologues in cryptic plasmid and phage genomes, but we show that these enzymes do not confer resistance to trimethoprim. Our methods also allow us to pinpoint the chromosomal origin of previously reported dfrA genes, and we show that many of these ancient chromosomal genes also confer resistance to trimethoprim. Our work reveals that trimethoprim resistance predated the clinical use of this chemotherapeutic agent, but that novel mutations have likely also arisen and become mobilized following its widespread use within and outside the clinic. Hence, this work confirms that resistance to novel drugs may already be present in the bacterial pangenome, and stresses the importance of rapid mobilization as a fundamental element in the emergence and global spread of resistance determinants.
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Affiliation(s)
- Miquel Sánchez-Osuna
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pilar Cortés
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Montserrat Llagostera
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Jordi Barbé
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Ivan Erill
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA
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9
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Eck T, Patel S, Candela T, Leon H K, Little M, Reis NE, Liyanagunawardana U, Gubler U, Janson CA, Catalano J, Goodey NM. Mutational analysis confirms the presence of distal inhibitor-selectivity determining residues in B. stearothermophilus dihydrofolate reductase. Arch Biochem Biophys 2020; 692:108545. [PMID: 32810476 PMCID: PMC10727455 DOI: 10.1016/j.abb.2020.108545] [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] [Received: 05/22/2020] [Revised: 08/08/2020] [Accepted: 08/12/2020] [Indexed: 11/20/2022]
Abstract
Many antibacterial and antiparasitic drugs work by competitively inhibiting dihydrofolate reductase (DHFR), a vital enzyme in folate metabolism. The interactions between inhibitors and DHFR active site residues are known in many homologs but the contributions from distal residues are less understood. Identifying distal residues that aid in inhibitor binding can improve targeted drug development programs by accounting for distant influences that may be less conserved and subject to frequent resistance causing mutations. Previously, a novel, homology-based, computational approach that mines ligand inhibition data was used to predict residues involved in inhibitor selectivity in the DHFR family. Expectedly, some inhibitor selectivity determining residue positions were predicted to lie in the active site and coincide with experimentally known inhibitor selectivity determining positions. However, other residues that group spatially in clusters distal to the active site have not been previously investigated. In this study, the effect of introducing amino acid substitutions at one of these predicted clusters (His38-Ala39-Ile40) on the inhibitor selectivity profile in Bacillus stearothermophilus dihydrofolate reductase (Bs DHFR) was investigated. Mutations were introduced into these cluster positions to change sidechain chemistry and size. We determined kcat and KM values and measured KD values at equilibrium for two competitive DHFR inhibitors, trimethoprim (TMP) and pyrimethamine (PYR). Mutations in the His38-Ala39-Ile40 cluster significantly impacted inhibitor binding and TMP/PYR selectivity - seven out of nine mutations resulted in tighter binding to PYR when compared to TMP. These data suggest that the His38-Ala39-Ile40 cluster is a distal inhibitor selectivity determining region that favors PYR binding in Bs DHFR and, possibly, throughout the DHFR family.
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Affiliation(s)
- Tyler Eck
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Seema Patel
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Thomas Candela
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Katherine Leon H
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Michael Little
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Natalia E Reis
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | | | - Ueli Gubler
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Cheryl A Janson
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Jaclyn Catalano
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA
| | - Nina M Goodey
- Dept. of Chemistry & Biochemistry, Montclair State University, Montclair, NJ, 07043, USA.
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10
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Genetic dominance governs the evolution and spread of mobile genetic elements in bacteria. Proc Natl Acad Sci U S A 2020; 117:15755-15762. [PMID: 32571917 PMCID: PMC7355013 DOI: 10.1073/pnas.2001240117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mobile genetic elements (MGEs), such as plasmids, promote bacterial evolution through horizontal gene transfer (HGT). However, the rules governing the repertoire of traits encoded on MGEs remain unclear. In this study, we uncovered the central role of genetic dominance shaping genetic cargo in MGEs, using antibiotic resistance as a model system. MGEs are typically present in more than one copy per host bacterium, and as a consequence, genetic dominance favors the fixation of dominant mutations over recessive ones. In addition, genetic dominance also determines the phenotypic effects of horizontally acquired MGE-encoded genes, silencing recessive alleles if the recipient bacterium already carries a wild-type copy of the gene. The combination of these two effects governs the catalog of genes encoded on MGEs. Our results help to understand how MGEs evolve and spread, uncovering the neglected influence of genetic dominance on bacterial evolution. Moreover, our findings offer a framework to forecast the spread and evolvability of MGE-encoded genes, which encode traits of key human interest, such as virulence or antibiotic resistance.
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11
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Kordus SL, Baughn AD. Revitalizing antifolates through understanding mechanisms that govern susceptibility and resistance. MEDCHEMCOMM 2019; 10:880-895. [PMID: 31303985 PMCID: PMC6595967 DOI: 10.1039/c9md00078j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 05/07/2019] [Indexed: 12/12/2022]
Abstract
In prokaryotes and eukaryotes, folate (vitamin B9) is an essential metabolic cofactor required for all actively growing cells. Specifically, folate serves as a one-carbon carrier in the synthesis of amino acids (such as methionine, serine, and glycine), N-formylmethionyl-tRNA, coenzyme A, purines and thymidine. Many microbes are unable to acquire folates from their environment and rely on de novo folate biosynthesis. In contrast, mammals lack the de novo folate biosynthesis pathway and must obtain folate from commensal microbiota or the environment using proton-coupled folate transporters. The essentiality and dichotomy between mammalian and bacterial folate biosynthesis and utilization pathways make it an ideal drug target for the development of antimicrobial agents and cancer chemotherapeutics. In this minireview, we discuss general aspects of folate biosynthesis and the underlying mechanisms that govern susceptibility and resistance of organisms to antifolate drugs.
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Affiliation(s)
- Shannon Lynn Kordus
- Department of Microbiology and Immunology , University of Minnesota , Minneapolis , MN , USA .
| | - Anthony David Baughn
- Department of Microbiology and Immunology , University of Minnesota , Minneapolis , MN , USA .
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12
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Ragheb MN, Thomason MK, Hsu C, Nugent P, Gage J, Samadpour AN, Kariisa A, Merrikh CN, Miller SI, Sherman DR, Merrikh H. Inhibiting the Evolution of Antibiotic Resistance. Mol Cell 2018; 73:157-165.e5. [PMID: 30449724 PMCID: PMC6320318 DOI: 10.1016/j.molcel.2018.10.015] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/17/2018] [Accepted: 10/09/2018] [Indexed: 11/30/2022]
Abstract
Efforts to battle antimicrobial resistance (AMR) are generally focused on developing novel antibiotics. However, history shows that resistance arises regardless of the nature or potency of new drugs. Here, we propose and provide evidence for an alternate strategy to resolve this problem: inhibiting evolution. We determined that the DNA translocase Mfd is an “evolvability factor” that promotes mutagenesis and is required for rapid resistance development to all antibiotics tested across highly divergent bacterial species. Importantly, hypermutator alleles that accelerate AMR development did not arise without Mfd, at least during evolution of trimethoprim resistance. We also show that Mfd’s role in AMR development depends on its interactions with the RNA polymerase subunit RpoB and the nucleotide excision repair protein UvrA. Our findings suggest that AMR development can be inhibited through inactivation of evolvability factors (potentially with “anti-evolution” drugs)—in particular, Mfd—providing an unexplored route toward battling the AMR crisis. The bacterial transcription-coupled repair (TCR) factor Mfd promotes mutagenesis Mfd-driven mutagenesis accelerates the evolution of antimicrobial resistance (AMR) The rapid evolution of AMR requires Mfd’s interaction with RpoB and UvrA Mfd may be an ideal target for “anti-evolution” drugs that inhibit AMR development
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Affiliation(s)
- Mark N Ragheb
- Department of Microbiology, University of Washington, Seattle, WA, USA; Molecular and Cellular Biology Graduate Program and Medical Scientist Training Program, University of Washington, Seattle, WA, USA
| | | | - Chris Hsu
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Patrick Nugent
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - John Gage
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | | | - Ankunda Kariisa
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | | | - Samuel I Miller
- Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - David R Sherman
- Center for Infectious Disease Research, Seattle, WA, USA; Interdiscipinary Program of Pathobiology, Department of Global Health, University of Washington, Seattle, WA, USA
| | - Houra Merrikh
- Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Genome Sciences, University of Washington, Seattle, WA, USA.
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13
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Srinivasan B, Tonddast-Navaei S, Roy A, Zhou H, Skolnick J. Chemical space of Escherichia coli dihydrofolate reductase inhibitors: New approaches for discovering novel drugs for old bugs. Med Res Rev 2018; 39:684-705. [PMID: 30192413 DOI: 10.1002/med.21538] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/16/2018] [Accepted: 08/09/2018] [Indexed: 12/15/2022]
Abstract
Escherichia coli Dihydrofolate reductase is an important enzyme that is essential for the survival of the Gram-negative microorganism. Inhibitors designed against this enzyme have demonstrated application as antibiotics. However, either because of poor bioavailability of the small-molecules resulting from their inability to cross the double membrane in Gram-negative bacteria or because the microorganism develops resistance to the antibiotics by mutating the DHFR target, discovery of new antibiotics against the enzyme is mandatory to overcome drug-resistance. This review summarizes the field of DHFR inhibition with special focus on recent efforts to effectively interface computational and experimental efforts to discover novel classes of inhibitors that target allosteric and active-sites in drug-resistant variants of EcDHFR.
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Affiliation(s)
- Bharath Srinivasan
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, Georgia
| | - Sam Tonddast-Navaei
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, Georgia
| | - Ambrish Roy
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, Georgia
| | - Hongyi Zhou
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, Georgia
| | - Jeffrey Skolnick
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, Georgia
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14
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Trade-offs with stability modulate innate and mutationally acquired drug resistance in bacterial dihydrofolate reductase enzymes. Biochem J 2018; 475:2107-2125. [PMID: 29871875 DOI: 10.1042/bcj20180249] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 01/30/2023]
Abstract
Structural stability is a major constraint on the evolution of protein sequences. However, under strong directional selection, mutations that confer novel phenotypes but compromise structural stability of proteins may be permissible. During the evolution of antibiotic resistance, mutations that confer drug resistance often have pleiotropic effects on the structure and function of antibiotic-target proteins, usually essential metabolic enzymes. In the present study, we show that trimethoprim (TMP)-resistant alleles of dihydrofolate reductase from Escherichia coli (EcDHFR) harboring the Trp30Gly, Trp30Arg or Trp30Cys mutations are significantly less stable than the wild-type, making them prone to aggregation and proteolysis. This destabilization is associated with a lower expression level, resulting in a fitness cost and negative epistasis with other TMP-resistant mutations in EcDHFR. Using structure-based mutational analysis, we show that perturbation of critical stabilizing hydrophobic interactions in wild-type EcDHFR enzyme explains the phenotypes of Trp30 mutants. Surprisingly, though crucial for the stability of EcDHFR, significant sequence variation is found at this site among bacterial dihydrofolate reductases (DHFRs). Mutational and computational analyses in EcDHFR and in DHFR enzymes from Staphylococcus aureus and Mycobacterium tuberculosis demonstrate that natural variation at this site and its interacting hydrophobic residues modulates TMP resistance in other bacterial DHFRs as well, and may explain the different susceptibilities of bacterial pathogens to TMP. Our study demonstrates that trade-offs between structural stability and function can influence innate drug resistance as well as the potential for mutationally acquired drug resistance of an enzyme.
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15
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Pathogenic Nocardia cyriacigeorgica and Nocardia nova Evolve To Resist Trimethoprim-Sulfamethoxazole by both Expected and Unexpected Pathways. Antimicrob Agents Chemother 2018; 62:AAC.00364-18. [PMID: 29686152 DOI: 10.1128/aac.00364-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 04/15/2018] [Indexed: 12/12/2022] Open
Abstract
Nocardia spp. are Gram-positive opportunistic pathogens that affect largely immunocompromised patients, leading to serious pulmonary or systemic infections. Combination therapy using the folate biosynthesis pathway inhibitors trimethoprim (TMP) and sulfamethoxazole (SMX) is commonly used as an antimicrobial therapy. Not surprisingly, as antibiotic therapies for nocardiosis can extend for many months, resistance to TMP-SMX has emerged. Using experimental evolution, we surveyed the genetic basis of adaptation to TMP-SMX across 8 strains of Nocardia nova and 2 strains of Nocardia cyriacigeorgica By employing both continuous experimental evolution to provide longitudinal information on the order of changes and characterization of resistant endpoint isolates, we observe changes that are consistent with modifications of two enzymes of the folate biosynthesis pathway: dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) (FolP), with the mutations often being clustered near the active site of the enzymes. While changes to DHFR and DHPS might be expected, we also noted that mutations in a previously undescribed homolog of DHPS (DHPS2 or FolP2) that was annotated as being "nonfunctional" were also sufficient to generate TMP-SMX resistance, which serves as a cautionary tale for the use of automated annotation by investigators and for the future discovery of drugs against this genus. Additionally, folP2 overlapped glucosyl-3-phosphoglycerate synthase. Remarkably, an adaptive frameshift mutation within the overlapping region resulted in a new in-frame fusion to the downstream gene to produce a potentially new bifunctional enzyme. How a single potentially bifunctional DHPS2 enzyme might confer resistance is unclear. However, it highlights the unexpected ways in which adaptive evolution finds novel solutions for selection.
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16
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Directed evolution of multiple genomic loci allows the prediction of antibiotic resistance. Proc Natl Acad Sci U S A 2018; 115:E5726-E5735. [PMID: 29871954 PMCID: PMC6016788 DOI: 10.1073/pnas.1801646115] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Antibiotic development is frequently plagued by the rapid emergence of drug resistance. However, assessing the risk of resistance development in the preclinical stage is difficult. Standard laboratory evolution approaches explore only a small fraction of the sequence space and fail to identify exceedingly rare resistance mutations and combinations thereof. Therefore, new rapid and exhaustive methods are needed to accurately assess the potential of resistance evolution and uncover the underlying mutational mechanisms. Here, we introduce directed evolution with random genomic mutations (DIvERGE), a method that allows an up to million-fold increase in mutation rate along the full lengths of multiple predefined loci in a range of bacterial species. In a single day, DIvERGE generated specific mutation combinations, yielding clinically significant resistance against trimethoprim and ciprofloxacin. Many of these mutations have remained previously undetected or provide resistance in a species-specific manner. These results indicate pathogen-specific resistance mechanisms and the necessity of future narrow-spectrum antibacterial treatments. In contrast to prior claims, we detected the rapid emergence of resistance against gepotidacin, a novel antibiotic currently in clinical trials. Based on these properties, DIvERGE could be applicable to identify less resistance-prone antibiotics at an early stage of drug development. Finally, we discuss potential future applications of DIvERGE in synthetic and evolutionary biology.
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17
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Abdizadeh H, Tamer YT, Acar O, Toprak E, Atilgan AR, Atilgan C. Increased substrate affinity in the Escherichia coli L28R dihydrofolate reductase mutant causes trimethoprim resistance. Phys Chem Chem Phys 2018; 19:11416-11428. [PMID: 28422217 DOI: 10.1039/c7cp01458a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dihydrofolate reductase (DHFR) is a ubiquitous enzyme with an essential role in cell metabolism. DHFR catalyzes the reduction of dihydrofolate to tetrahydrofolate, which is a precursor for purine and thymidylate synthesis. Several DHFR targeting antifolate drugs including trimethoprim, a competitive antibacterial inhibitor, have therefore been developed and are clinically used. Evolution of resistance against antifolates is a common public health problem rendering these drugs ineffective. To combat the resistance problem, it is important to understand resistance-conferring changes in the DHFR structure and accordingly develop alternative strategies. Here, we structurally and dynamically characterize Escherichia coli DHFR in its wild type (WT) and trimethoprim resistant L28R mutant forms in the presence of the substrate and its inhibitor trimethoprim. We use molecular dynamics simulations to determine the conformational space, loop dynamics and hydrogen bond distributions at the active site of DHFR for the WT and the L28R mutant. We also report their experimental kcat, Km, and Ki values, accompanied by isothermal titration calorimetry measurements of DHFR that distinguish enthalpic and entropic contributions to trimethoprim binding. Although mutations that confer resistance to competitive inhibitors typically make enzymes more promiscuous and decrease affinity to both the substrate and the inhibitor, strikingly, we find that the L28R mutant has a unique resistance mechanism. While the binding affinity differences between the WT and the mutant for the inhibitor and the substrate are small, the newly formed extra hydrogen bonds with the aminobenzoyl glutamate tail of DHF in the L28R mutant leads to increased barriers for the dissociation of the substrate and the product. Therefore, the L28R mutant indirectly gains resistance by enjoying prolonged binding times in the enzyme-substrate complex. While this also leads to slower product release and decreases the catalytic rate of the L28R mutant, the overall effect is the maintenance of a sufficient product formation rate. Finally, the experimental and computational analyses together reveal the changes that occur in the energetic landscape of DHFR upon the resistance-conferring L28R mutation. We show that the negative entropy associated with the binding of trimethoprim in WT DHFR is due to water organization at the binding interface. Our study lays the framework to study structural changes in other trimethoprim resistant DHFR mutants.
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Affiliation(s)
- Haleh Abdizadeh
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey.
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18
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Westbroek ML, Geahlen RL. Modulation of BCR Signaling by the Induced Dimerization of Receptor-Associated SYK. Antibodies (Basel) 2017; 6:antib6040023. [PMID: 31548538 PMCID: PMC6698873 DOI: 10.3390/antib6040023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/27/2017] [Accepted: 12/02/2017] [Indexed: 01/14/2023] Open
Abstract
Clustering of the B cell antigen receptor (BCR) by polyvalent antigens is transmitted through the SYK tyrosine kinase to the activation of multiple intracellular pathways that determine the physiological consequences of receptor engagement. To explore factors that modulate the quantity and quality of signals sent by the crosslinked BCR, we developed a novel chemical mediator of dimerization to induce clustering of receptor-associated SYK. To accomplish this, we fused SYK with E. coli dihydrofolate reductase (eDHFR), which binds the small molecule trimethoprim (TMP) with high affinity and selectivity and synthesized a dimer of TMP with a flexible linker. The TMP dimer is able to induce the aggregation of eDHFR-linked SYK in live cells. The induced dimerization of SYK bound to the BCR differentially regulates the activation of downstream transcription factors, promoting the activation of Nuclear Factor of Activated T cells (NFAT) without affecting the activation of NFκB. The dimerization of SYK enhances the duration but not the amplitude of calcium mobilization by enhancing the extent and duration of its interaction with the crosslinked BCR at the plasma membrane.
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Affiliation(s)
- Mark L Westbroek
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
| | - Robert L Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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19
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Korsak D, Krawczyk-Balska A. Identification of the Molecular Mechanism of Trimethoprim Resistance inListeria monocytogenes. Foodborne Pathog Dis 2017; 14:696-700. [PMID: 28910155 DOI: 10.1089/fpd.2017.2323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Dorota Korsak
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
| | - Agata Krawczyk-Balska
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
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20
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Abstract
The standard genetic code is robust to mutations during transcription and translation. Point mutations are likely to be synonymous or to preserve the chemical properties of the original amino acid. Saturation mutagenesis experiments suggest that in some cases the best-performing mutant requires replacement of more than a single nucleotide within a codon. These replacements are essentially inaccessible to common error-based laboratory engineering techniques that alter a single nucleotide per mutation event, due to the extreme rarity of adjacent mutations. In this theoretical study, we suggest a radical reordering of the genetic code that maximizes the mutagenic potential of single nucleotide replacements. We explore several possible genetic codes that allow a greater degree of accessibility to the mutational landscape and may result in a hyperevolvable organism that could serve as an ideal platform for directed evolution experiments. We then conclude by evaluating the challenges of constructing such recoded organisms and their potential applications within the field of synthetic biology. The conservative nature of the genetic code prevents bioengineers from efficiently accessing the full mutational landscape of a gene via common error-prone methods. Here, we present two computational approaches to generate alternative genetic codes with increased accessibility. These new codes allow mutational transitions to a larger pool of amino acids and with a greater extent of chemical differences, based on a single nucleotide replacement within the codon, thus increasing evolvability both at the single-gene and at the genome levels. Given the widespread use of these techniques for strain and protein improvement, along with more fundamental evolutionary biology questions, the use of recoded organisms that maximize evolvability should significantly improve the efficiency of directed evolution, library generation, and fitness maximization.
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21
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Srinivasan B, Rodrigues JV, Tonddast-Navaei S, Shakhnovich E, Skolnick J. Rational Design of Novel Allosteric Dihydrofolate Reductase Inhibitors Showing Antibacterial Effects on Drug-Resistant Escherichia coli Escape Variants. ACS Chem Biol 2017; 12:1848-1857. [PMID: 28525268 DOI: 10.1021/acschembio.7b00175] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In drug discovery, systematic variations of substituents on a common scaffold and bioisosteric replacements are often used to generate diversity and obtain molecules with better biological effects. However, this could saturate the small-molecule diversity pool resulting in drug resistance. On the other hand, conventional drug discovery relies on targeting known pockets on protein surfaces leading to drug resistance by mutations of critical pocket residues. Here, we present a two-pronged strategy of designing novel drugs that target unique pockets on a protein's surface to overcome the above problems. Dihydrofolate reductase, DHFR, is a critical enzyme involved in thymidine and purine nucleotide biosynthesis. Several classes of compounds that are structural analogues of the substrate dihydrofolate have been explored for their antifolate activity. Here, we describe 10 novel small-molecule inhibitors of Escherichia coli DHFR, EcDHFR, belonging to the stilbenoid, deoxybenzoin, and chalcone family of compounds discovered by a combination of pocket-based virtual ligand screening and systematic scaffold hopping. These inhibitors show a unique uncompetitive or noncompetitive inhibition mechanism, distinct from those reported for all known inhibitors of DHFR, indicative of binding to a unique pocket distinct from either substrate or cofactor-binding pockets. Furthermore, we demonstrate that rescue mutants of EcDHFR, with reduced affinity to all known classes of DHFR inhibitors, are inhibited at the same concentration as the wild-type. These compounds also exhibit antibacterial activity against E. coli harboring the drug-resistant variant of DHFR. This discovery is the first report on a novel class of inhibitors targeting a unique pocket on EcDHFR.
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Affiliation(s)
- Bharath Srinivasan
- Center
for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332, United States
| | - João V. Rodrigues
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Sam Tonddast-Navaei
- Center
for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332, United States
| | - Eugene Shakhnovich
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Jeffrey Skolnick
- Center
for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, Georgia 30332, United States
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22
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Viberg LT, Sarovich DS, Kidd TJ, Geake JB, Bell SC, Currie BJ, Price EP. Within-Host Evolution of Burkholderia pseudomallei during Chronic Infection of Seven Australasian Cystic Fibrosis Patients. mBio 2017; 8:e00356-17. [PMID: 28400528 PMCID: PMC5388805 DOI: 10.1128/mbio.00356-17] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 03/15/2017] [Indexed: 12/14/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic disorder characterized by progressive lung function decline. CF patients are at an increased risk of respiratory infections, including those by the environmental bacterium Burkholderia pseudomallei, the causative agent of melioidosis. Here, we compared the genomes of B. pseudomallei isolates collected between ~4 and 55 months apart from seven chronically infected CF patients. Overall, the B. pseudomallei strains showed evolutionary patterns similar to those of other chronic infections, including emergence of antibiotic resistance, genome reduction, and deleterious mutations in genes involved in virulence, metabolism, environmental survival, and cell wall components. We documented the first reported B. pseudomallei hypermutators, which were likely caused by defective MutS. Further, our study identified both known and novel molecular mechanisms conferring resistance to three of the five clinically important antibiotics for melioidosis treatment. Our report highlights the exquisite adaptability of microorganisms to long-term persistence in their environment and the ongoing challenges of antibiotic treatment in eradicating pathogens in the CF lung. Convergent evolution with other CF pathogens hints at a degree of predictability in bacterial evolution in the CF lung and potential targeted eradication of chronic CF infections in the future.IMPORTANCEBurkholderia pseudomallei, the causative agent of melioidosis, is an environmental opportunistic bacterium that typically infects immunocompromised people and those with certain risk factors such as cystic fibrosis (CF). Patients with CF tend to develop chronic melioidosis infections, for reasons that are not well understood. This report is the first to describe B. pseudomallei evolution within the CF lung during chronic infection. We show that the pathways by which B. pseudomallei adapts to the CF lung are similar to those seen in better-studied CF pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia complex species. Adaptations include the accumulation of antibiotic resistance, loss of nonessential genes, metabolic alterations, and virulence factor attenuation. Known and novel mechanisms of resistance to three of the five antibiotics used in melioidosis treatment were identified. Similar pathways of evolution in CF pathogens, including B. pseudomallei, provide exciting avenues for more-targeted treatment of chronic, recalcitrant infections.
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Affiliation(s)
- Linda T Viberg
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Derek S Sarovich
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
| | - Timothy J Kidd
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland
- Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - James B Geake
- Department of Respiratory Medicine, The Lyell McEwin Hospital, Elizabeth Vale, South Australia, Australia
| | - Scott C Bell
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- Department of Thoracic Medicine, The Prince Charles Hospital, Chermside, Queensland, Australia
| | - Bart J Currie
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
- Department of Infectious Diseases and Northern Territory Medical Program, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - Erin P Price
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
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23
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Cammarata M, Thyer R, Lombardo M, Anderson A, Wright D, Ellington A, Brodbelt JS. Characterization of trimethoprim resistant E. coli dihydrofolate reductase mutants by mass spectrometry and inhibition by propargyl-linked antifolates. Chem Sci 2017; 8:4062-4072. [PMID: 29967675 PMCID: PMC6020862 DOI: 10.1039/c6sc05235e] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 03/24/2017] [Indexed: 12/12/2022] Open
Abstract
Native mass spectrometry, size exclusion chromatography, and kinetic assays were employed to study trimethoprim resistance in E. coli caused by mutations P21L and W30R of dihydrofolate reductase.
Pathogenic Escherichia coli, one of the primary causes of urinary tract infections, has shown significant resistance to the most popular antibiotic, trimethoprim (TMP), which inhibits dihydrofolate reductase (DHFR). The resistance is modulated by single point mutations of DHFR. The impact of two clinically relevant mutations, P21L and W30R, on the activity of DHFR was evaluated via measurement of Michaelis–Menten and inhibitory kinetics, and structural characterization was undertaken by native mass spectrometry with ultraviolet photodissociation (UVPD). Compared to WT-DHFR, both P21L and W30R mutants produced less stable complexes with TMP in the presence of co-factor NADPH as evidenced by the relative abundances of complexes observed in ESI mass spectra. Moreover, based on variations in the fragmentation patterns obtained by UVPD mass spectrometry of binary and ternary DHFR complexes, notable structural changes were localized to the substrate binding pocket for W30R and to the M20 loop region as well as the C-terminal portion containing the essential G–H functional loop for the P21L mutant. The results suggest that the mutations confer resistance through distinctive mechanisms. A novel propargyl-linked antifolate compound 1038 was shown to be a reasonably effective inhibitor of the P21L mutant.
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Affiliation(s)
- Michael Cammarata
- Department of Chemistry , University of Texas , Austin , TX 78712 , USA .
| | - Ross Thyer
- Center for Systems and Synthetic Biology , University of Texas , Austin , TX 78712 , USA
| | - Michael Lombardo
- Department of Pharmaceutical Sciences , University of Connecticut , Storrs , CT 06269 , USA
| | - Amy Anderson
- Department of Pharmaceutical Sciences , University of Connecticut , Storrs , CT 06269 , USA
| | - Dennis Wright
- Department of Pharmaceutical Sciences , University of Connecticut , Storrs , CT 06269 , USA
| | - Andrew Ellington
- Center for Systems and Synthetic Biology , University of Texas , Austin , TX 78712 , USA
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Ligand-promoted protein folding by biased kinetic partitioning. Nat Chem Biol 2017; 13:369-371. [PMID: 28218913 PMCID: PMC5362304 DOI: 10.1038/nchembio.2303] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 12/12/2016] [Indexed: 01/03/2023]
Abstract
Protein folding in cells occurs in the presence of high concentrations of endogenous binding partners, and exogenous binding partners have been exploited as pharmacological chaperones. A combined mathematical modeling and experimental approach shows that a ligand improves the folding of a destabilized protein by biasing the kinetic partitioning between folding and alternative fates (aggregation or degradation). Computationally predicted inhibition of test protein aggregation and degradation as a function of ligand concentration are validated by experiments in two disparate cellular systems.
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25
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Genome-wide mapping of mutations at single-nucleotide resolution for protein, metabolic and genome engineering. Nat Biotechnol 2016; 35:48-55. [PMID: 27941803 DOI: 10.1038/nbt.3718] [Citation(s) in RCA: 242] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 10/05/2016] [Indexed: 01/20/2023]
Abstract
Improvements in DNA synthesis and sequencing have underpinned comprehensive assessment of gene function in bacteria and eukaryotes. Genome-wide analyses require high-throughput methods to generate mutations and analyze their phenotypes, but approaches to date have been unable to efficiently link the effects of mutations in coding regions or promoter elements in a highly parallel fashion. We report that CRISPR-Cas9 gene editing in combination with massively parallel oligomer synthesis can enable trackable editing on a genome-wide scale. Our method, CRISPR-enabled trackable genome engineering (CREATE), links each guide RNA to homologous repair cassettes that both edit loci and function as barcodes to track genotype-phenotype relationships. We apply CREATE to site saturation mutagenesis for protein engineering, reconstruction of adaptive laboratory evolution experiments, and identification of stress tolerance and antibiotic resistance genes in bacteria. We provide preliminary evidence that CREATE will work in yeast. We also provide a webtool to design multiplex CREATE libraries.
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26
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Oz T, Guvenek A, Yildiz S, Karaboga E, Tamer YT, Mumcuyan N, Ozan VB, Senturk GH, Cokol M, Yeh P, Toprak E. Strength of selection pressure is an important parameter contributing to the complexity of antibiotic resistance evolution. Mol Biol Evol 2014; 31:2387-401. [PMID: 24962091 PMCID: PMC4137714 DOI: 10.1093/molbev/msu191] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Revealing the genetic changes responsible for antibiotic resistance can be critical for developing novel antibiotic therapies. However, systematic studies correlating genotype to phenotype in the context of antibiotic resistance have been missing. In order to fill in this gap, we evolved 88 isogenic Escherichia coli populations against 22 antibiotics for 3 weeks. For every drug, two populations were evolved under strong selection and two populations were evolved under mild selection. By quantifying evolved populations’ resistances against all 22 drugs, we constructed two separate cross-resistance networks for strongly and mildly selected populations. Subsequently, we sequenced representative colonies isolated from evolved populations for revealing the genetic basis for novel phenotypes. Bacterial populations that evolved resistance against antibiotics under strong selection acquired high levels of cross-resistance against several antibiotics, whereas other bacterial populations evolved under milder selection acquired relatively weaker cross-resistance. In addition, we found that strongly selected strains against aminoglycosides became more susceptible to five other drug classes compared with their wild-type ancestor as a result of a point mutation on TrkH, an ion transporter protein. Our findings suggest that selection strength is an important parameter contributing to the complexity of antibiotic resistance problem and use of high doses of antibiotics to clear infections has the potential to promote increase of cross-resistance in clinics.
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Affiliation(s)
- Tugce Oz
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Aysegul Guvenek
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Sadik Yildiz
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Enes Karaboga
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Yusuf Talha Tamer
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Nirva Mumcuyan
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Vedat Burak Ozan
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Gizem Hazal Senturk
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Murat Cokol
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Pamela Yeh
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles
| | - Erdal Toprak
- Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
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Trimethoprim resistance of dihydrofolate reductase variants from clinical isolates of Pneumocystis jirovecii. Antimicrob Agents Chemother 2013; 57:4990-8. [PMID: 23896474 DOI: 10.1128/aac.01161-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pneumocystis jirovecii is an opportunistic pathogen that causes serious pneumonia in immunosuppressed patients. Standard therapy and prophylaxis include trimethoprim (TMP)-sulfamethoxazole; trimethoprim in this combination targets dihydrofolate reductase (DHFR). Fourteen clinically observed variants of P. jirovecii DHFR were produced recombinantly to allow exploration of the causes of clinically observed failure of therapy and prophylaxis that includes trimethoprim. Six DHFR variants (S31F, F36C, L65P, A67V, V79I, and I158V) showed resistance to inhibition by trimethoprim, with Ki values for trimethoprim 4-fold to 100-fold higher than those for the wild-type P. jirovecii DHFR. An experimental antifolate with more conformational flexibility than trimethoprim showed strong activity against one trimethoprim-resistant variant. The two variants that were most resistant to trimethoprim (F36C and L65P) also had increased Km values for dihydrofolic acid (DHFA). The catalytic rate constant (kcat) was unchanged for most variant forms of P. jirovecii DHFR but was significantly lowered in F36C protein; one naturally occurring variant with two amino acid substitutions (S106P and E127G) showed a doubling of kcat, as well as a Km for NADPH half that of the wild type. The strongest resistance to trimethoprim occurred with amino acid changes in the binding pocket for DHFA or trimethoprim, and the strongest effect on binding of NADPH was linked to a mutation involved in binding the phosphate group of the cofactor. This study marks the first confirmation that naturally occurring mutations in the gene for DHFR from P. jirovecii produce variant forms of DHFR that are resistant to trimethoprim and may contribute to clinically observed failures of standard therapy or prophylaxis.
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Screening libraries for improved solubility: using E. coli dihydrofolate reductase as a reporter. Methods Mol Biol 2013. [PMID: 23423901 DOI: 10.1007/978-1-62703-293-3_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Low protein solubility is a problem in many areas of protein science. Although chemical methods have been developed to solubilize proteins these are not always effective and add to the cost of producing the protein. One way of overcoming these difficulties is to evolve the protein to be more soluble. A major hurdle in this process is the ability to select mutant proteins with enhanced solubility from a large library of randomly mutated proteins. In this article, we describe such a method. The method relies on the fact that increasing the expression of dihydrofolate reductase (DHFR) makes Escherichia coli resistant to Trimethoprim (TMP). Proteins fused to DHFR will produce chimeras with altered levels of resistance to TMP. This variation in TMP resistance can be used to identify mutant proteins with enhanced solubility.
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Toprak E, Veres A, Michel JB, Chait R, Hartl DL, Kishony R. Evolutionary paths to antibiotic resistance under dynamically sustained drug selection. Nat Genet 2011; 44:101-5. [PMID: 22179135 PMCID: PMC3534735 DOI: 10.1038/ng.1034] [Citation(s) in RCA: 498] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 11/15/2011] [Indexed: 12/31/2022]
Abstract
Antibiotic resistance can evolve through the sequential accumulation of multiple mutations. To study such gradual evolution, we developed a selection device, the 'morbidostat', that continuously monitors bacterial growth and dynamically regulates drug concentrations, such that the evolving population is constantly challenged. We analyzed the evolution of resistance in Escherichia coli under selection with single drugs, including chloramphenicol, doxycycline and trimethoprim. Over a period of ∼20 days, resistance levels increased dramatically, with parallel populations showing similar phenotypic trajectories. Whole-genome sequencing of the evolved strains identified mutations both specific to resistance to a particular drug and shared in resistance to multiple drugs. Chloramphenicol and doxycycline resistance evolved smoothly through diverse combinations of mutations in genes involved in translation, transcription and transport. In contrast, trimethoprim resistance evolved in a stepwise manner, through mutations restricted to the gene encoding the enzyme dihydrofolate reductase (DHFR). Sequencing of DHFR over the time course of the experiment showed that parallel populations evolved similar mutations and acquired them in a similar order.
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Affiliation(s)
- Erdal Toprak
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Adrian Veres
- Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - Jean-Baptiste Michel
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts, USA
| | - Remy Chait
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel L. Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Roy Kishony
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
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Loveridge EJ, Dawson WM, Evans RM, Sobolewska A, Allemann RK. Reduced Susceptibility of Moritella profunda Dihydrofolate Reductase to Trimethoprim is Not Due to Glutamate 28. Protein J 2011; 30:546-8. [DOI: 10.1007/s10930-011-9361-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Kumar A, Chakraborti S, Joshi P, Chakrabarti P, Chakraborty R. A multiple antibiotic and serum resistant oligotrophic strain, Klebsiella pneumoniae MB45 having novel dfrA30, is sensitive to ZnO QDs. Ann Clin Microbiol Antimicrob 2011; 10:19. [PMID: 21595893 PMCID: PMC3118321 DOI: 10.1186/1476-0711-10-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 05/19/2011] [Indexed: 11/22/2022] Open
Abstract
Background The aim of this study was to describe a novel trimethoprim resistance gene cassette, designated dfrA30, within a class 1 integron in a facultatively oligotrophic, multiple antibiotic and human serum resistant test strain, MB45, in a population of oligotrophic bacteria isolated from the river Mahananda; and to test the efficiency of surface bound acetate on zinc oxide quantum dots (ZnO QDs) as bactericidal agent on MB45. Methods Diluted Luria broth/Agar (10-3) media was used to cultivate the oligotrophic bacteria from water sample. Multiple antibiotic resistant bacteria were selected by employing replica plate method. A rapid assay was performed to determine the sensitivity/resistance of the test strain to human serum. Variable region of class 1 integron was cloned, sequenced and the expression of gene coding for antibiotic resistance was done in Escherichia coli JM 109. Identity of culture was determined by biochemical phenotyping and 16S rRNA gene sequence analyses. A phylogenetic tree was constructed based on representative trimethoprim resistance-mediating DfrA proteins retrieved from GenBank. Growth kinetic studies for the strain MB45 were performed in presence of varied concentrations of ZnO QDs. Results and conclusions The facultatively oligotrophic strain, MB45, resistant to human serum and ten antibiotics trimethoprim, cotrimoxazole, ampicillin, gentamycin, netilmicin, tobramycin, chloramphenicol, cefotaxime, kanamycin and streptomycin, has been identified as a new strain of Klebsiella pneumoniae. A novel dfr gene, designated as dfrA30, found integrated in class 1 integron was responsible for resistance to trimethoprim in Klebsiella pneumoniae strain MB45. The growth of wild strain MB45 was 100% arrested at 500 mg/L concentration of ZnO QDs. To our knowledge this is the first report on application of ZnO quantum dots to kill multiple antibiotics and serum resistant K. pneumoniae strain.
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Affiliation(s)
- Arvind Kumar
- Department of Biotechnology, University of North Bengal, Siliguri, West Bengal, India
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Carroll MJ, Gromova AV, Miller KR, Tang H, Wang XS, Tripathy A, Singleton SF, Collins EJ, Lee AL. Direct detection of structurally resolved dynamics in a multiconformation receptor-ligand complex. J Am Chem Soc 2011; 133:6422-8. [PMID: 21469679 DOI: 10.1021/ja2005253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Structure-based drug design relies on static protein structures despite significant evidence for the need to include protein dynamics as a serious consideration. In practice, dynamic motions are neglected because they are not understood well enough to model, a situation resulting from a lack of explicit experimental examples of dynamic receptor-ligand complexes. Here, we report high-resolution details of pronounced ~1 ms time scale motions of a receptor-small molecule complex using a combination of NMR and X-ray crystallography. Large conformational dynamics in Escherichia coli dihydrofolate reductase are driven by internal switching motions of the drug-like, nanomolar-affinity inhibitor. Carr-Purcell-Meiboom-Gill relaxation dispersion experiments and NOEs revealed the crystal structure to contain critical elements of the high energy protein-ligand conformation. The availability of accurate, structurally resolved dynamics in a protein-ligand complex should serve as a valuable benchmark for modeling dynamics in other receptor-ligand complexes and prediction of binding affinities.
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Affiliation(s)
- Mary J Carroll
- Division of Medicinal Chemistry and Natural Products, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Beierlein JM, Karri NG, Anderson AC. Targeted mutations of Bacillus anthracis dihydrofolate reductase condense complex structure−activity relationships. J Med Chem 2010; 53:7327-36. [PMID: 20882962 DOI: 10.1021/jm100727t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several antifolates, including trimethoprim (TMP) and a series of propargyl-linked analogues, bind dihydrofolate reductase from Bacillus anthracis (BaDHFR) with lower affinity than is typical in other bacterial species. To guide lead optimization for BaDHFR, we explored a new approach to determine structure-activity relationships whereby the enzyme is altered and the analogues remain constant, essentially reversing the standard experimental design. Active site mutants of the enzyme, Ba(F96I)DHFR and Ba(Y102F)DHFR, were created and evaluated with enzyme inhibition assays and crystal structures. The affinities of the antifolates increase up to 60-fold with the Y102F mutant, suggesting that interactions with Tyr 102 are critical for affinity. Crystal structures of the enzymes bound to TMP and propargyl-linked inhibitors reveal the basis of TMP resistance and illuminate the influence of Tyr 102 on the lipophilic linker between the pyrimidine and aryl rings. Two new inhibitors test and validate these conclusions and show the value of the technique for providing new directions during lead optimization.
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Affiliation(s)
- Jennifer M Beierlein
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N Eagleville Road, Storrs, Connecticut 06269, USA
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Mutational 'hot-spots' in mammalian, bacterial and protozoal dihydrofolate reductases associated with antifolate resistance: sequence and structural comparison. Drug Resist Updat 2009; 12:28-41. [PMID: 19272832 DOI: 10.1016/j.drup.2009.02.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 12/24/2008] [Accepted: 02/04/2009] [Indexed: 12/16/2022]
Abstract
Human dihydrofolate reductase (DHFR) is a primary target for antifolate drugs in cancer treatment, while DHFRs from Plasmodium falciparum, Plasmodium vivax and various bacterial species are primary targets in the treatment of malaria and bacterial infections. Mutations in each of these DHFRs can result in resistance towards clinically relevant antifolates. We review the structural and functional impact of active-site mutations with respect to enzyme activity and antifolate resistance of DHFRs from mammals, protozoa and bacteria. The high structural homology between DHFRs results in a number of cross-species, active-site 'hot-spots' for broad-based antifolate resistance. In addition, we identify mutations that confer species-specific resistance, or antifolate-specific resistance. This comparative review of antifolate binding in diverse species provides new insights into the relationship between antifolate design and the development of mutational resistance. It also presents avenues for designing antifolate-resistant mammalian DHFRs as chemoprotective agents.
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