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Suwanthada P, Kongsoi S, Jayaweera S, Akapelwa ML, Thapa J, Nakajima C, Suzuki Y. Interplay between Amino Acid Substitution in GyrA and QnrB19: Elevating Fluoroquinolone Resistance in Salmonella Typhimurium. ACS Infect Dis 2024. [PMID: 38898378 DOI: 10.1021/acsinfecdis.4c00150] [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: 06/21/2024]
Abstract
Globally, there have been increasing reports of antimicrobial resistance in nontyphoidal Salmonella (NTS), which can develop into severe and potentially life-threatening diarrhea. This study focuses on the synergistic effects of DNA gyrase mutations and plasmid-mediated quinolone resistance (PMQR) genes, specifically qnrB19, on fluoroquinolone (FQ) resistance in Salmonella Typhimurium. By utilizing recombinant mutants, GyrAS83F and GyrAD87N, and QnrB19's, we discovered a significant increase in fluoroquinolones resistance when QnrB19 is present. Specifically, ciprofloxacin and moxifloxacin's inhibitory concentrations rose 10- and 8-fold, respectively. QnrB19 was found to enhance the resistance capacity of mutant DNA gyrases, leading to high-level FQ resistance. Additionally, we observed that the ratio of QnrB19 to DNA gyrase played a critical role in determining whether QnrB19 could protect DNA gyrase against FQ inhibition. Our findings underscore the critical need to understand these resistance mechanisms, as their coexistence enables bacteria to withstand therapeutic FQ levels, posing a significant challenge to treatment efficacy.
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Affiliation(s)
- Pondpan Suwanthada
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
| | - Siriporn Kongsoi
- Department of Veterinary Public Health, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 73140, Thailand
| | - Sasini Jayaweera
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
| | - Mwangala Lonah Akapelwa
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
| | - Jeewan Thapa
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
- Hokkaido University Institute for Vaccine Research & Development, Hokkaido University, Sapporo 001-0020, Japan
| | - Chie Nakajima
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
- Hokkaido University Institute for Vaccine Research & Development, Hokkaido University, Sapporo 001-0020, Japan
- International Collaboration Unit, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
| | - Yasuhiko Suzuki
- Division of Bioresources, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
- Hokkaido University Institute for Vaccine Research & Development, Hokkaido University, Sapporo 001-0020, Japan
- International Collaboration Unit, Hokkaido University International Institute for Zoonosis Control, Sapporo 001-0020, Japan
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Joel EO, Akinlabi OC, Olaposi AV, Olowomofe TO, Adekanmbi AO. High carriage of plasmid-mediated quinolone resistance (PMQR) genes by ESBL-producing and fluoroquinolone-resistant Escherichia coli recovered from animal waste dumps. Mol Biol Rep 2024; 51:424. [PMID: 38491992 DOI: 10.1007/s11033-024-09228-8] [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: 07/27/2023] [Accepted: 01/08/2024] [Indexed: 03/18/2024]
Abstract
BACKGROUND There has been a rise in the consumption of fluoroquinolones in human and veterinary medicine recently. This has contributed to the rising incidence of quinolone resistance in bacteria. This study aimed at the determination of the antibiotic resistance profile of ESBL-producing and fluoroquinolone-resistant E. coli (FQEC) isolated from animal waste obtained from the waste dumps of an agricultural farm and their carriage of genes encoding PMQR. METHODS AND RESULTS Isolation of ESBL-producing E. coli from animal waste samples was done on CHROMagar ESBL, while presumptive isolates were purified, and identified via the detection of uidA gene. Susceptibility to a panel of ten antibiotics was done using the disc diffusion method, and detection of PMQR genes (qnrA, qnrB, qnrS, aac(6')-lb-cr, qepA and oqxAB) was done using monoplex and duplex PCR. Twenty-five ESBL-producing and FQEC were obtained from the cattle (6), piggery (7) and poultry (12) waste dumps of the farm. There was 100% resistance to cefpodoxime, cefotaxime, enrofloxacin, trimethoprim-sulfamethoxazole and penicillin by the isolates. The resistance to the other antibiotics was streptomycin (48%), ceftazidime (24%), while no isolate resisted amoxicillin-clavulanate and imipenem. The frequencies of PMQR genes detected were; qnrA (96%), oqxAB (96%), qnrB (92%), while qnrS was detected in 88% (22) of the isolates. Aminoglycoside acetyltransferase (aac(6')-lb-cr) and quinolone efflux pump (qepA) were each detected in 20 (80%) of the isolates. CONCLUSIONS This study showed that animal wastes disposed indiscriminately into dumps could be a budding 'hotspot' for multidrug resistant, ESBL-producing and fluoroquinolone-resistant E. coli carrying multiple genes encoding resistance to fluoroquinolone antibiotics.
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Affiliation(s)
- Elizabeth Omokoshi Joel
- Department of Animal Science, Faculty of Agriculture, University of Ibadan, Ibadan, Nigeria
- Molecular Biology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria
| | - Olabisi Comfort Akinlabi
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria.
| | - Adedolapo Victoria Olaposi
- Environmental Microbiology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria
- Molecular Biology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria
| | | | - Abimbola Olumide Adekanmbi
- Environmental Microbiology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria.
- Molecular Biology and Biotechnology Laboratory, Department of Microbiology, University of Ibadan, Ibadan, Nigeria.
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3
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Ruan S, Tu CH, Bourne CR. Friend or Foe: Protein Inhibitors of DNA Gyrase. BIOLOGY 2024; 13:84. [PMID: 38392303 PMCID: PMC10886550 DOI: 10.3390/biology13020084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/20/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
DNA gyrase is essential for the successful replication of circular chromosomes, such as those found in most bacterial species, by relieving topological stressors associated with unwinding the double-stranded genetic material. This critical central role makes gyrase a valued target for antibacterial approaches, as exemplified by the highly successful fluoroquinolone class of antibiotics. It is reasonable that the activity of gyrase could be intrinsically regulated within cells, thereby helping to coordinate DNA replication with doubling times. Numerous proteins have been identified to exert inhibitory effects on DNA gyrase, although at lower doses, it can appear readily reversible and therefore may have regulatory value. Some of these, such as the small protein toxins found in plasmid-borne addiction modules, can promote cell death by inducing damage to DNA, resulting in an analogous outcome as quinolone antibiotics. Others, however, appear to transiently impact gyrase in a readily reversible and non-damaging mechanism, such as the plasmid-derived Qnr family of DNA-mimetic proteins. The current review examines the origins and known activities of protein inhibitors of gyrase and highlights opportunities to further exert control over bacterial growth by targeting this validated antibacterial target with novel molecular mechanisms. Furthermore, we are gaining new insights into fundamental regulatory strategies of gyrase that may prove important for understanding diverse growth strategies among different bacteria.
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Affiliation(s)
- Shengfeng Ruan
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
| | - Chih-Han Tu
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
| | - Christina R Bourne
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
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4
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Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:microorganisms10061239. [PMID: 35744757 PMCID: PMC9228545 DOI: 10.3390/microorganisms10061239] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.
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Millanao AR, Mora AY, Villagra NA, Bucarey SA, Hidalgo AA. Biological Effects of Quinolones: A Family of Broad-Spectrum Antimicrobial Agents. Molecules 2021; 26:7153. [PMID: 34885734 PMCID: PMC8658791 DOI: 10.3390/molecules26237153] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/28/2021] [Accepted: 11/05/2021] [Indexed: 11/28/2022] Open
Abstract
Broad antibacterial spectrum, high oral bioavailability and excellent tissue penetration combined with safety and few, yet rare, unwanted effects, have made the quinolones class of antimicrobials one of the most used in inpatients and outpatients. Initially discovered during the search for improved chloroquine-derivative molecules with increased anti-malarial activity, today the quinolones, intended as antimicrobials, comprehend four generations that progressively have been extending antimicrobial spectrum and clinical use. The quinolone class of antimicrobials exerts its antimicrobial actions through inhibiting DNA gyrase and Topoisomerase IV that in turn inhibits synthesis of DNA and RNA. Good distribution through different tissues and organs to treat Gram-positive and Gram-negative bacteria have made quinolones a good choice to treat disease in both humans and animals. The extensive use of quinolones, in both human health and in the veterinary field, has induced a rise of resistance and menace with leaving the quinolones family ineffective to treat infections. This review revises the evolution of quinolones structures, biological activity, and the clinical importance of this evolving family. Next, updated information regarding the mechanism of antimicrobial activity is revised. The veterinary use of quinolones in animal productions is also considered for its environmental role in spreading resistance. Finally, considerations for the use of quinolones in human and veterinary medicine are discussed.
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Affiliation(s)
- Ana R. Millanao
- Facultad de Ciencias, Instituto de Farmacia, Universidad Austral de Chile, Valdivia 5090000, Chile;
| | - Aracely Y. Mora
- Programa de Doctorado en Bioquímica, Universidad de Chile, Santiago 8380544, Chile;
| | - Nicolás A. Villagra
- Escuela de Tecnología Médica, Universidad Andres Bello, Santiago 8370071, Chile;
| | - Sergio A. Bucarey
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago 8820808, Chile;
| | - Alejandro A. Hidalgo
- Escuela de Química y Farmacia, Universidad Andres Bello, Santiago 8370071, Chile
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Escherichia coli GyrA Tower Domain Interacts with QnrB1 Loop B and Plays an Important Role in QnrB1 Protection from Quinolone Inhibition. Antimicrob Agents Chemother 2021; 65:e0040221. [PMID: 33846132 DOI: 10.1128/aac.00402-21] [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: 11/20/2022] Open
Abstract
The Qnr pentapeptide repeat proteins interact with DNA gyrase and protect it from quinolone inhibition. The two external loops, particularly the larger loop B, of Qnr proteins are essential for quinolone protection of DNA gyrase. The specific QnrB1 interaction sites on DNA gyrase are not known. In this study, we investigated the interaction between GyrA and QnrB1 using site-specific photo-cross-linking of QnrB1 loop B combined with mass spectrometry. We found that amino acid residues 286 to 298 on the tower domain of GyrA interact with QnrB1 and play a key role in QnrB1 protection of gyrase from quinolone inhibition. Alanine replacement of arginine at residue 293 and a small deletion of amino acids 286 to 289 of GyrA resulted in a decrease in the QnrB1-mediated increase in quinolone MICs and also abolished the QnrB1 protection of purified DNA gyrase from ciprofloxacin inhibition.
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7
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Mazurek Ł, Ghilarov D, Michalczyk E, Pakosz Z, Metelev M, Czyszczoń W, Wawro K, Behroz I, Dubiley S, Süssmuth RD, Heddle JG. Pentapeptide repeat protein QnrB1 requires ATP hydrolysis to rejuvenate poisoned gyrase complexes. Nucleic Acids Res 2021; 49:1581-1596. [PMID: 33434265 PMCID: PMC7897471 DOI: 10.1093/nar/gkaa1266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/16/2020] [Accepted: 01/06/2021] [Indexed: 11/14/2022] Open
Abstract
DNA gyrase, a type II topoisomerase found predominantly in bacteria, is the target for a variety of 'poisons', namely natural product toxins (e.g. albicidin, microcin B17) and clinically important synthetic molecules (e.g. fluoroquinolones). Resistance to both groups can be mediated by pentapeptide repeat proteins (PRPs). Despite long-term studies, the mechanism of action of these protective PRPs is not known. We show that a PRP, QnrB1 provides specific protection against fluoroquinolones, which strictly requires ATP hydrolysis by gyrase. QnrB1 binds to the GyrB protein and stimulates ATPase activity of the isolated N-terminal ATPase domain of GyrB (GyrB43). We probed the QnrB1 binding site using site-specific incorporation of a photoreactive amino acid and mapped the crosslinks to the GyrB43 protein. We propose a model in which QnrB1 binding allosterically promotes dissociation of the fluoroquinolone molecule from the cleavage complex.
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Affiliation(s)
- Łukasz Mazurek
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.,Postgraduate School of Molecular Medicine, Warsaw, Poland
| | - Dmitry Ghilarov
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | | | - Zuzanna Pakosz
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.,Postgraduate School of Molecular Medicine, Warsaw, Poland
| | | | - Wojciech Czyszczoń
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Karolina Wawro
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Iraj Behroz
- Institute of Biological Chemistry, Technische Universität Berlin, Berlin, Germany
| | | | - Roderich D Süssmuth
- Institute of Biological Chemistry, Technische Universität Berlin, Berlin, Germany
| | - Jonathan G Heddle
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
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8
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Abstract
While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6')Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.
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9
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The role of parC, parE, and qnrB Genes in Ciprofloxacin-Resistant Escherichia coli Isolates from Urinary Tract Infections. ARCHIVES OF PEDIATRIC INFECTIOUS DISEASES 2017. [DOI: 10.5812/pedinfect.41504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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10
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Hooper DC, Jacoby GA. Topoisomerase Inhibitors: Fluoroquinolone Mechanisms of Action and Resistance. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025320. [PMID: 27449972 DOI: 10.1101/cshperspect.a025320] [Citation(s) in RCA: 255] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Quinolone antimicrobials are widely used in clinical medicine and are the only current class of agents that directly inhibit bacterial DNA synthesis. Quinolones dually target DNA gyrase and topoisomerase IV binding to specific domains and conformations so as to block DNA strand passage catalysis and stabilize DNA-enzyme complexes that block the DNA replication apparatus and generate double breaks in DNA that underlie their bactericidal activity. Resistance has emerged with clinical use of these agents and is common in some bacterial pathogens. Mechanisms of resistance include mutational alterations in drug target affinity and efflux pump expression and acquisition of resistance-conferring genes. Resistance mutations in one or both of the two drug target enzymes are commonly in a localized domain of the GyrA and ParC subunits of gyrase and topoisomerase IV, respectively, and reduce drug binding to the enzyme-DNA complex. Other resistance mutations occur in regulatory genes that control the expression of native efflux pumps localized in the bacterial membrane(s). These pumps have broad substrate profiles that include other antimicrobials as well as quinolones. Mutations of both types can accumulate with selection pressure and produce highly resistant strains. Resistance genes acquired on plasmids confer low-level resistance that promotes the selection of mutational high-level resistance. Plasmid-encoded resistance is because of Qnr proteins that protect the target enzymes from quinolone action, a mutant aminoglycoside-modifying enzyme that also modifies certain quinolones, and mobile efflux pumps. Plasmids with these mechanisms often encode additional antimicrobial resistances and can transfer multidrug resistance that includes quinolones.
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Affiliation(s)
- David C Hooper
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - George A Jacoby
- Lahey Hospital and Medical Center, Burlington, Massachusetts 01805
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Campioni F, Souza RA, Martins VV, Stehling EG, Bergamini AMM, Falcão JP. Prevalence of gyrA Mutations in Nalidixic Acid-Resistant Strains of Salmonella Enteritidis Isolated from Humans, Food, Chickens, and the Farm Environment in Brazil. Microb Drug Resist 2016; 23:421-428. [PMID: 27559761 DOI: 10.1089/mdr.2016.0024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Salmonella Enteritidis strains that are resistant to nalidixic acid and exhibit reduced susceptibility to fluoroquinolones have been increasing worldwide. In Brazil, few studies have been conducted to elucidate the quinolone resistance mechanisms of S. Enteritidis strains. This study analyzed the profile of gyrA, gyrB, parC, and parE mutations and plasmid-mediated quinolone resistance (PMQR) mechanisms in S. Enteritidis NalR strains isolated in Brazil. Moreover, the minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated in 84 NalR strains and compared with 20 NalS strains. The mutation profiles of the gyrA gene were accessed by high-resolution melting analysis and gyrB, parC, and parE by quinolone resistance-determining region sequencing. The MICs of ciprofloxacin were accessed with Etest®. The strains were divided into five gyrA melting profiles. The NalR strains exhibited the following amino acid substitutions: Ser97→Pro, Ser83→Phe, Asp87→Asn, or Asp87→Tyr. The average MICs of ciprofloxacin was 0.006 μg/ml in the NalS and 0.09 μg/ml in the NalR strains. No points of mutation were observed in the genes gyrB, parC, and parE. The qnrB gene was found in two strains. In conclusion, the reduced susceptibility to ciprofloxacin observed in NalR strains may cause treatment failures once this drug is commonly used to treat Salmonella infections. Moreover, this reduced susceptibility in these Brazilian strains was provided by target alteration of gene gyrA and not by mobile elements, such as resistance plasmids.
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Affiliation(s)
- Fábio Campioni
- 1 Universidade de São Paulo - Faculdade de Ciências Farmacêuticas de Ribeirão Preto , Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Ribeirão Preto, Brazil
| | - Roberto Antonio Souza
- 1 Universidade de São Paulo - Faculdade de Ciências Farmacêuticas de Ribeirão Preto , Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Ribeirão Preto, Brazil
| | - Vinicius Vicente Martins
- 1 Universidade de São Paulo - Faculdade de Ciências Farmacêuticas de Ribeirão Preto , Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Ribeirão Preto, Brazil
| | - Eliana Guedes Stehling
- 1 Universidade de São Paulo - Faculdade de Ciências Farmacêuticas de Ribeirão Preto , Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Ribeirão Preto, Brazil
| | | | - Juliana Pfrimer Falcão
- 1 Universidade de São Paulo - Faculdade de Ciências Farmacêuticas de Ribeirão Preto , Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Ribeirão Preto, Brazil
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Mutational Analysis of Quinolone Resistance Protein QnrVC7 Provides Novel Insights into the Structure-Activity Relationship of Qnr Proteins. Antimicrob Agents Chemother 2016; 60:1939-42. [PMID: 26824937 DOI: 10.1128/aac.01805-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 01/03/2016] [Indexed: 11/20/2022] Open
Abstract
This study assessed the functional importance of residues located at the i(-2) position of face 4 of the tandem repeat loops of the quinolone resistance protein QnrVC7 through mutagenesis studies. The i(-2) position of face 4 on different coils required residues with different natures. Some substitutions reduced the protective activity of QnrVC7, while some of them increased it. These findings advanced our understanding on the detailed structural organization and functional requirements of Qnr proteins.
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13
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Mutations That Enhance the Ciprofloxacin Resistance of Escherichia coli with qnrA1. Antimicrob Agents Chemother 2015; 60:1537-45. [PMID: 26711751 DOI: 10.1128/aac.02167-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/13/2015] [Indexed: 01/20/2023] Open
Abstract
Plasmid-mediated qnr genes provide only a modest decrease in quinolone susceptibility but facilitate the selection of higher-level resistance. In Escherichia coli strain J53 without qnr, ciprofloxacin resistance often involves mutations in the GyrA subunit of DNA gyrase. Mutations in gyrA were absent, however, when 43 mutants with decreased ciprofloxacin susceptibility were selected from J53(pMG252) with qnrA1. Instead, in 13 mutants, individual and whole-genome sequencing identified mutations in marR and soxR associated with increased expression of marA and soxS and, through them, increased expression of the AcrAB pump, which effluxes quinolones. Nine mutants had increased expression of the MdtE efflux pump, and six demonstrated increased expression of the ydhE pump gene. Many efflux mutants also had increased resistance to novobiocin, another pump substrate, but other mutants were novobiocin hypersusceptible. Mutations in rfaD and rfaE in the pathway for inner core lipopolysaccharide (LPS) biosynthesis were identified in five such strains. Many of the pump and LPS mutants had decreased expression of OmpF, the major porin channel for ciprofloxacin entry. Three mutants had increased expression of qnrA that persisted when pMG252 from these strains was outcrossed. gyrA mutations were also rare when mutants with decreased ciprofloxacin susceptibility were selected from E. coli J53 with aac(6')-Ib-cr or qepA. We suggest that multiple genes conferring low-level resistance contribute to enhanced ciprofloxacin resistance selected from an E. coli strain carrying qnrA1, aac(6')-Ib-cr, or qepA because these determinants decrease the effective ciprofloxacin concentration and allow more common but lower-resistance mutations than those in gyrA to predominate.
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14
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Protective effect of Qnr on agents other than quinolones that target DNA gyrase. Antimicrob Agents Chemother 2015; 59:6689-95. [PMID: 26239981 DOI: 10.1128/aac.01292-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/30/2015] [Indexed: 12/16/2022] Open
Abstract
Qnr is a plasmid-encoded and chromosomally determined protein that protects DNA gyrase and topoisomerase IV from inhibition by quinolones. Despite its prevalence worldwide and existence prior to the discovery of quinolones, its native function is not known. Other synthetic compounds and natural products also target bacterial topoisomerases. A number were studied as molecular probes to gain insight into how Qnr acts. Qnr blocked inhibition by synthetic compounds with somewhat quinolone-like structure that target the GyrA subunit, such as the 2-pyridone ABT-719, the quinazoline-2,4-dione PD 0305970, and the spiropyrimidinetrione pyrazinyl-alkynyl-tetrahydroquinoline (PAT), indicating that Qnr is not strictly quinolone specific, but Qnr did not protect against GyrA-targeting simocyclinone D8 despite evidence that both simocyclinone D8 and Qnr affect DNA binding to gyrase. Qnr did not affect the activity of tricyclic pyrimidoindole or pyrazolopyridones, synthetic inhibitors of the GyrB subunit, or nonsynthetic GyrB inhibitors, such as coumermycin A1, novobiocin, gyramide A, or microcin B17.Thus, in this set of compounds the protective activity of Qnr was confined to those that, like quinolones, trap gyrase on DNA in cleaved complexes.
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