1
|
Oviatt A, Gibson EG, Huang J, Mattern K, Neuman KC, Chan PF, Osheroff N. Interactions between Gepotidacin and Escherichia coli Gyrase and Topoisomerase IV: Genetic and Biochemical Evidence for Well-Balanced Dual-Targeting. ACS Infect Dis 2024; 10:1137-1151. [PMID: 38606465 PMCID: PMC11015057 DOI: 10.1021/acsinfecdis.3c00346] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 02/07/2024] [Accepted: 02/13/2024] [Indexed: 04/13/2024]
Abstract
Antimicrobial resistance is a global threat to human health. Therefore, efforts have been made to develop new antibacterial agents that address this critical medical issue. Gepotidacin is a novel, bactericidal, first-in-class triazaacenaphthylene antibacterial in clinical development. Recently, phase III clinical trials for gepotidacin treatment of uncomplicated urinary tract infections caused by uropathogens, including Escherichia coli, were stopped for demonstrated efficacy. Because of the clinical promise of gepotidacin, it is important to understand how the compound interacts with its cellular targets, gyrase and topoisomerase IV, from E. coli. Consequently, we determined how gyrase and topoisomerase IV mutations in amino acid residues that are involved in gepotidacin interactions affect the susceptibility of E. coli cells to the compound and characterized the effects of gepotidacin on the activities of purified wild-type and mutant gyrase and topoisomerase IV. Gepotidacin displayed well-balanced dual-targeting of gyrase and topoisomerase IV in E. coli cells, which was reflected in a similar inhibition of the catalytic activities of these enzymes by the compound. Gepotidacin induced gyrase/topoisomerase IV-mediated single-stranded, but not double-stranded, DNA breaks. Mutations in GyrA and ParC amino acid residues that interact with gepotidacin altered the activity of the compound against the enzymes and, when present in both gyrase and topoisomerase IV, reduced the antibacterial activity of gepotidacin against this mutant strain. Our studies provide insights regarding the well-balanced dual-targeting of gyrase and topoisomerase IV by gepotidacin in E. coli.
Collapse
Affiliation(s)
- Alexandria
A. Oviatt
- Department
of Biochemistry, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
| | - Elizabeth G. Gibson
- Department
of Biochemistry, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
- Department
of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
| | - Jianzhong Huang
- Infectious
Diseases Research Unit, GlaxoSmithKline, Collegeville, Pennsylvania 19426, United States
| | - Karen Mattern
- Infectious
Diseases Research Unit, GlaxoSmithKline, Collegeville, Pennsylvania 19426, United States
| | - Keir C. Neuman
- Laboratory
of Single Molecule Biophysics, National
Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20982, United States
| | - Pan F. Chan
- Infectious
Diseases Research Unit, GlaxoSmithKline, Collegeville, Pennsylvania 19426, United States
| | - Neil Osheroff
- Department
of Biochemistry, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232, United States
- Department
of Medicine (Hematology/Oncology), Vanderbilt
University School of Medicine, Nashville, Tennessee 37232, United States
- VA
Tennessee
Valley Healthcare System, Nashville, Tennessee 37212, United States
| |
Collapse
|
2
|
Hemez C, Clarelli F, Palmer AC, Bleis C, Abel S, Chindelevitch L, Cohen T, Abel zur Wiesch P. Mechanisms of antibiotic action shape the fitness landscapes of resistance mutations. Comput Struct Biotechnol J 2022; 20:4688-4703. [PMID: 36147681 PMCID: PMC9463365 DOI: 10.1016/j.csbj.2022.08.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 08/12/2022] [Accepted: 08/12/2022] [Indexed: 11/15/2022] Open
Abstract
Antibiotic-resistant pathogens are a major public health threat. A deeper understanding of how an antibiotic's mechanism of action influences the emergence of resistance would aid in the design of new drugs and help to preserve the effectiveness of existing ones. To this end, we developed a model that links bacterial population dynamics with antibiotic-target binding kinetics. Our approach allows us to derive mechanistic insights on drug activity from population-scale experimental data and to quantify the interplay between drug mechanism and resistance selection. We find that both bacteriostatic and bactericidal agents can be equally effective at suppressing the selection of resistant mutants, but that key determinants of resistance selection are the relationships between the number of drug-inactivated targets within a cell and the rates of cellular growth and death. We also show that heterogeneous drug-target binding within a population enables resistant bacteria to evolve fitness-improving secondary mutations even when drug doses remain above the resistant strain's minimum inhibitory concentration. Our work suggests that antibiotic doses beyond this "secondary mutation selection window" could safeguard against the emergence of high-fitness resistant strains during treatment.
Collapse
Affiliation(s)
- Colin Hemez
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Graduate Program in Biophysics, Harvard University, Boston, MA 02115, USA
- Corresponding authors at: Broad Institute, 75 Ames St, Room 3035, Cambridge, MA 02412, USA (C. Hemez). Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway (P. Abel zur Wiesch).
| | - Fabrizio Clarelli
- Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Adam C. Palmer
- Department of Pharmacology, Computational Medicine Program, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Christina Bleis
- Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Sören Abel
- Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Division of Infection Control, Norwegian Institute of Public Health, Oslo 0318, Norway
| | - Leonid Chindelevitch
- Department of Infectious Disease Epidemiology, Imperial College, London SW7 2AZ, UK
| | - Theodore Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT 06520, USA
| | - Pia Abel zur Wiesch
- Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Division of Infection Control, Norwegian Institute of Public Health, Oslo 0318, Norway
- Corresponding authors at: Broad Institute, 75 Ames St, Room 3035, Cambridge, MA 02412, USA (C. Hemez). Department of Pharmacy, UiT – The Arctic University of Norway, 9019 Tromsø, Norway (P. Abel zur Wiesch).
| |
Collapse
|
3
|
Huang SYN, Michaels SA, Mitchell BB, Majdalani N, Vanden Broeck A, Canela A, Tse-Dinh YC, Lamour V, Pommier Y. Exonuclease VII repairs quinolone-induced damage by resolving DNA gyrase cleavage complexes. SCIENCE ADVANCES 2021; 7:7/10/eabe0384. [PMID: 33658195 PMCID: PMC7929499 DOI: 10.1126/sciadv.abe0384] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/19/2021] [Indexed: 05/25/2023]
Abstract
The widely used quinolone antibiotics act by trapping prokaryotic type IIA topoisomerases, resulting in irreversible topoisomerase cleavage complexes (TOPcc). Whereas the excision repair pathways of TOPcc in eukaryotes have been extensively studied, it is not known whether equivalent repair pathways for prokaryotic TOPcc exist. By combining genetic, biochemical, and molecular biology approaches, we demonstrate that exonuclease VII (ExoVII) excises quinolone-induced trapped DNA gyrase, an essential prokaryotic type IIA topoisomerase. We show that ExoVII repairs trapped type IIA TOPcc and that ExoVII displays tyrosyl nuclease activity for the tyrosyl-DNA linkage on the 5'-DNA overhangs corresponding to trapped type IIA TOPcc. ExoVII-deficient bacteria fail to remove trapped DNA gyrase, consistent with their hypersensitivity to quinolones. We also identify an ExoVII inhibitor that synergizes with the antimicrobial activity of quinolones, including in quinolone-resistant bacterial strains, further demonstrating the functional importance of ExoVII for the repair of type IIA TOPcc.
Collapse
Affiliation(s)
- Shar-Yin N Huang
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
| | - Stephanie A Michaels
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Brianna B Mitchell
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Nadim Majdalani
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Arnaud Vanden Broeck
- Integrated Structural Biology Department, IGBMC, UMR7104 CNRS, U1258 Inserm, University of Strasbourg, Illkirch 67404, France
| | - Andres Canela
- The Hakubi Center for Advanced Research, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Valerie Lamour
- Integrated Structural Biology Department, IGBMC, UMR7104 CNRS, U1258 Inserm, University of Strasbourg, Illkirch 67404, France
| | - Yves Pommier
- Laboratory of Molecular Pharmacology, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
| |
Collapse
|
4
|
Ojkic N, Lilja E, Direito S, Dawson A, Allen RJ, Waclaw B. A Roadblock-and-Kill Mechanism of Action Model for the DNA-Targeting Antibiotic Ciprofloxacin. Antimicrob Agents Chemother 2020; 64:e02487-19. [PMID: 32601161 PMCID: PMC7449190 DOI: 10.1128/aac.02487-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 06/19/2020] [Indexed: 12/19/2022] Open
Abstract
Fluoroquinolones, antibiotics that cause DNA damage by inhibiting DNA topoisomerases, are clinically important, but their mechanism of action is not yet fully understood. In particular, the dynamical response of bacterial cells to fluoroquinolone exposure has hardly been investigated, although the SOS response, triggered by DNA damage, is often thought to play a key role. Here, we investigated the growth inhibition of the bacterium Escherichia coli by the fluoroquinolone ciprofloxacin at low concentrations. We measured the long-term and short-term dynamical response of the growth rate and DNA production rate to ciprofloxacin at both the population and single-cell levels. We show that, despite the molecular complexity of DNA metabolism, a simple roadblock-and-kill model focusing on replication fork blockage and DNA damage by ciprofloxacin-poisoned DNA topoisomerase II (gyrase) quantitatively reproduces long-term growth rates in the presence of ciprofloxacin. The model also predicts dynamical changes in the DNA production rate in wild-type E. coli and in a recombination-deficient mutant following a step-up of ciprofloxacin. Our work highlights that bacterial cells show a delayed growth rate response following fluoroquinolone exposure. Most importantly, our model explains why the response is delayed: it takes many doubling times to fragment the DNA sufficiently to inhibit gene expression. We also show that the dynamical response is controlled by the timescale of DNA replication and gyrase binding/unbinding to the DNA rather than by the SOS response, challenging the accepted view. Our work highlights the importance of including detailed biophysical processes in biochemical-systems models to quantitatively predict the bacterial response to antibiotics.
Collapse
Affiliation(s)
- Nikola Ojkic
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Elin Lilja
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Susana Direito
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Angela Dawson
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Rosalind J Allen
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Synthetic and Systems Biology, Edinburgh, United Kingdom
| | - Bartlomiej Waclaw
- SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Synthetic and Systems Biology, Edinburgh, United Kingdom
| |
Collapse
|
5
|
Sinha D, Kiianitsa K, Sherman DR, Maizels N. Rapid, direct detection of bacterial topoisomerase 1-DNA adducts by RADAR/ELISA. Anal Biochem 2020; 608:113827. [PMID: 32738213 DOI: 10.1016/j.ab.2020.113827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 10/23/2022]
Abstract
Topoisomerases are proven drug targets, but antibiotics that poison bacterial Topoisomerase 1 (Top1) have yet to be discovered. We have developed a rapid and direct assay for quantification of Top1-DNA adducts that is suitable for high throughput assays. Adducts are recovered by "RADAR fractionation", a quick, convenient approach in which cells are lysed in chaotropic salts and detergent and nucleic acids and covalently bound adducts then precipitated with alcohol. Here we show that RADAR fractionation followed by ELISA immunodetection can quantify adducts formed by wild-type and mutant Top1 derivatives encoded by two different bacterial pathogens, Y. pestis and M. tuberculosis, expressed in E. coli or M. smegmatis, respectively. For both enzymes, quantification of adducts by RADAR/ELISA produces results comparable to the more cumbersome classical approach of CsCl density gradient fractionation. The experiments reported here establish that RADAR/ELISA assay offers a simple way to characterize Top1 mutants and analyze kinetics of adduct formation and repair. They also provide a foundation for discovery and optimization of drugs that poison bacterial Top1 using standard high-throughput approaches.
Collapse
Affiliation(s)
- Devapriya Sinha
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA.
| | - David R Sherman
- Department of Microbiology, University of Washington, 815 Republican St., Seattle, WA, 98102, USA
| | - Nancy Maizels
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA; Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA
| |
Collapse
|
6
|
Pham TDM, Ziora ZM, Blaskovich MAT. Quinolone antibiotics. MEDCHEMCOMM 2019; 10:1719-1739. [PMID: 31803393 PMCID: PMC6836748 DOI: 10.1039/c9md00120d] [Citation(s) in RCA: 311] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
Abstract
The quinolone antibiotics arose in the early 1960s, with the first examples possessing a narrow-spectrum of activity with unfavorable pharmacokinetic properties. Over time, the development of new quinolone antibiotics has led to improved analogues with an expanded spectrum and high efficacy. Nowadays, quinolones are widely used for treating a variety of infections. Quinolones are broad-spectrum antibiotics that are active against both Gram-positive and Gram-negative bacteria, including mycobacteria, and anaerobes. They exert their actions by inhibiting bacterial nucleic acid synthesis through disrupting the enzymes topoisomerase IV and DNA gyrase, and by causing breakage of bacterial chromosomes. However, bacteria have acquired resistance to quinolones, similar to other antibacterial agents, due to the overuse of these drugs. Mechanisms contributing to quinolone resistance are mediated by chromosomal mutations and/or plasmid gene uptake that alter the topoisomerase targets, modify the quinolone, and/or reduce drug accumulation by either decreased uptake or increased efflux. This review discusses the development of this class of antibiotics in terms of potency, pharmacokinetics and toxicity, along with the resistance mechanisms which reduce the quinolones' activity against pathogens. Potential strategies for future generations of quinolone antibiotics with enhanced activity against resistant strains are suggested.
Collapse
Affiliation(s)
- Thu D M Pham
- School of Chemistry & Molecular Biosciences , The University of Queensland , Brisbane , QLD 4072 , Australia
| | - Zyta M Ziora
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia .
| | - Mark A T Blaskovich
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , QLD 4072 , Australia .
| |
Collapse
|
7
|
Cao N, Tan K, Annamalai T, Joachimiak A, Tse-Dinh YC. Investigating mycobacterial topoisomerase I mechanism from the analysis of metal and DNA substrate interactions at the active site. Nucleic Acids Res 2019; 46:7296-7308. [PMID: 29905859 PMCID: PMC6101483 DOI: 10.1093/nar/gky492] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/25/2018] [Indexed: 12/18/2022] Open
Abstract
We have obtained new crystal structures of Mycobacterium tuberculosis topoisomerase I, including structures with ssDNA substrate bound to the active site, with and without Mg2+ ion present. Significant enzyme conformational changes upon DNA binding place the catalytic tyrosine in a pre-transition state position for cleavage of a specific phosphodiester linkage. Meanwhile, the enzyme/DNA complex with bound Mg2+ ion may represent the post-transition state for religation in the enzyme's multiple-step DNA relaxation catalytic cycle. The first observation of Mg2+ ion coordinated with the TOPRIM residues and DNA phosphate in a type IA topoisomerase active site allows assignment of likely catalytic role for the metal and draws a comparison to the proposed mechanism for type IIA topoisomerases. The critical function of a strictly conserved glutamic acid in the DNA cleavage step was assessed through site-directed mutagenesis. The functions assigned to the observed Mg2+ ion can account for the metal requirement for DNA rejoining but not DNA cleavage by type IA topoisomerases. This work provides new structural insights into a more stringent requirement for DNA rejoining versus cleavage in the catalytic cycle of this essential enzyme, and further establishes the potential for selective interference of DNA rejoining by this validated TB drug target.
Collapse
Affiliation(s)
- Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Kemin Tan
- Structural Biology Center, Biosciences, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Andrzej Joachimiak
- Structural Biology Center, Biosciences, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| |
Collapse
|
8
|
A RADAR-Based Assay to Isolate Covalent DNA Complexes in Bacteria. Antibiotics (Basel) 2019; 8:antibiotics8010017. [PMID: 30818799 PMCID: PMC6466838 DOI: 10.3390/antibiotics8010017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 02/14/2019] [Accepted: 02/21/2019] [Indexed: 01/03/2023] Open
Abstract
Quinolone antibacterials target the type II topoisomerases gyrase and topoisomerase IV and kill bacterial cells by converting these essential enzymes into cellular poisons. Although much is known regarding the interactions between these drugs and enzymes in purified systems, much less is known regarding their interactions in the cellular context due to the lack of a widely accessible assay that does not require expensive, specialized equipment. Thus, we developed an assay, based on the “rapid approach to DNA adduct recovery,” or RADAR, assay that is used with cultured human cells, to measure cleavage complex levels induced by treating bacterial cultures with the quinolone ciprofloxacin. Many chemical and mechanical lysis conditions and DNA precipitation conditions were tested, and the method involving sonication in denaturing conditions followed by precipitation of DNA via addition of a half volume of ethanol provided the most consistent results. This assay can be used to complement results obtained with purified enzymes to expand our understanding of quinolone mechanism of action and to test the activity of newly developed topoisomerase-targeted compounds. In addition, the bacterial RADAR assay can be used in other contexts, as any proteins covalently complexed to DNA should be trapped on and isolated with the DNA, allowing them to then be quantified.
Collapse
|
9
|
Mills M, Tse-Dinh YC, Neuman KC. Direct observation of topoisomerase IA gate dynamics. Nat Struct Mol Biol 2018; 25:1111-1118. [PMID: 30478267 PMCID: PMC6379066 DOI: 10.1038/s41594-018-0158-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/31/2018] [Indexed: 12/18/2022]
Abstract
Type IA topoisomerases cleave single-stranded DNA and relieve negative supercoils in discrete steps corresponding to the passage of the intact DNA strand through the cleaved strand. Although type IA topoisomerases are assumed to accomplish this strand passage via a protein-mediated DNA gate, opening of this gate has never been observed. We developed a single-molecule assay to directly measure gate opening of the Escherichia coli type IA topoisomerases I and III. We found that after cleavage of single-stranded DNA, the protein gate opens by as much as 6.6 nm and can close against forces in excess of 16 pN. Key differences in the cleavage, ligation, and gate dynamics of these two enzymes provide insights into their different cellular functions. The single-molecule results are broadly consistent with conformational changes obtained from molecular dynamics simulations. These results allowed us to develop a mechanistic model of interactions between type IA topoisomerases and single-stranded DNA.
Collapse
Affiliation(s)
- Maria Mills
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yuk-Ching Tse-Dinh
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
10
|
Nontargeted Metabolomics Reveals the Multilevel Response to Antibiotic Perturbations. Cell Rep 2018; 19:1214-1228. [PMID: 28494870 DOI: 10.1016/j.celrep.2017.04.002] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/27/2016] [Accepted: 03/31/2017] [Indexed: 11/21/2022] Open
Abstract
Microbes have shown a remarkable ability in evading the killing actions of antimicrobial agents, such that treatment of bacterial infections represents once more an urgent global challenge. Understanding the initial bacterial response to antimicrobials may reveal intrinsic tolerance mechanisms to antibiotics and suggest alternative and less conventional therapeutic strategies. Here, we used mass spectrometry-based metabolomics to monitor the immediate metabolic response of Escherichia coli to a variety of antibiotic perturbations. We show that rapid metabolic changes can reflect drug mechanisms of action and reveal the active role of metabolism in mediating the first stress response to antimicrobials. We uncovered a role for ammonium imbalance in aggravating chloramphenicol toxicity and the essential function of deoxythymidine 5'-diphosphate (dTDP)-rhamnose synthesis for the immediate transcriptional upregulation of GyrA in response to quinolone antibiotics. Our results suggest bacterial metabolism as an attractive target to interfere with the early bacterial response to antibiotic treatments and reduce the probability for survival and eventual evolution of antibiotic resistance.
Collapse
|
11
|
Ashley RE, Dittmore A, McPherson SA, Turnbough CL, Neuman KC, Osheroff N. Activities of gyrase and topoisomerase IV on positively supercoiled DNA. Nucleic Acids Res 2017; 45:9611-9624. [PMID: 28934496 PMCID: PMC5766186 DOI: 10.1093/nar/gkx649] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/14/2017] [Indexed: 11/12/2022] Open
Abstract
Although bacterial gyrase and topoisomerase IV have critical interactions with positively supercoiled DNA, little is known about the actions of these enzymes on overwound substrates. Therefore, the abilities of Bacillus anthracis and Escherichia coli gyrase and topoisomerase IV to relax and cleave positively supercoiled DNA were analyzed. Gyrase removed positive supercoils ∼10-fold more rapidly and more processively than it introduced negative supercoils into relaxed DNA. In time-resolved single-molecule measurements, gyrase relaxed overwound DNA with burst rates of ∼100 supercoils per second (average burst size was 6.2 supercoils). Efficient positive supercoil removal required the GyrA-box, which is necessary for DNA wrapping. Topoisomerase IV also was able to distinguish DNA geometry during strand passage and relaxed positively supercoiled substrates ∼3-fold faster than negatively supercoiled molecules. Gyrase maintained lower levels of cleavage complexes with positively supercoiled (compared with negatively supercoiled) DNA, whereas topoisomerase IV generated similar levels with both substrates. Results indicate that gyrase is better suited than topoisomerase IV to safely remove positive supercoils that accumulate ahead of replication forks. They also suggest that the wrapping mechanism of gyrase may have evolved to promote rapid removal of positive supercoils, rather than induction of negative supercoils.
Collapse
Affiliation(s)
- Rachel E Ashley
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Andrew Dittmore
- Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20982, USA
| | - Sylvia A McPherson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Charles L Turnbough
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20982, USA
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.,VA Tennessee Valley Healthcare System, Nashville, TN 37212, USA.,Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232-6307, USA
| |
Collapse
|
12
|
Ashley RE, Lindsey RH, McPherson SA, Turnbough CL, Kerns RJ, Osheroff N. Interactions between Quinolones and Bacillus anthracis Gyrase and the Basis of Drug Resistance. Biochemistry 2017; 56:4191-4200. [PMID: 28708938 PMCID: PMC5560241 DOI: 10.1021/acs.biochem.7b00203] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
Gyrase appears to
be the primary cellular target for quinolone
antibacterials in multiple pathogenic bacteria, including Bacillus anthracis, the causative agent of anthrax. Given
the significance of this type II topoisomerase as a drug target, it
is critical to understand how quinolones interact with gyrase and
how specific mutations lead to resistance. However, these important
issues have yet to be addressed for a canonical gyrase. Therefore,
we utilized a mechanistic approach to characterize interactions of
quinolones with wild-type B. anthracis gyrase and
enzymes containing the most common quinolone resistance mutations.
Results indicate that clinically relevant quinolones interact with
the enzyme through a water–metal ion bridge in which a noncatalytic
divalent metal ion is chelated by the C3/C4 keto acid of the drug.
In contrast to other bacterial type II topoisomerases that have been
examined, the bridge is anchored to gyrase primarily through a single
residue (Ser85). Substitution of groups at the quinolone C7 and C8
positions generated drugs that were less dependent on the water–metal
ion bridge and overcame resistance. Thus, by analyzing the interactions
of drugs with type II topoisomerases from individual bacteria, it
may be possible to identify specific quinolone derivatives that can
overcome target-mediated resistance in important pathogenic species.
Collapse
Affiliation(s)
| | | | - Sylvia A McPherson
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama 35294, United States
| | - Charles L Turnbough
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, Alabama 35294, United States
| | - Robert J Kerns
- Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa College of Pharmacy , Iowa City, Iowa 52242, United States
| | - Neil Osheroff
- VA Tennessee Valley Healthcare System , Nashville, Tennessee 37212, United States
| |
Collapse
|
13
|
Targeting bacterial topoisomerase I to meet the challenge of finding new antibiotics. Future Med Chem 2016; 7:459-71. [PMID: 25875873 DOI: 10.4155/fmc.14.157] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Resistance of bacterial pathogens to current antibiotics has grown to be an urgent crisis. Approaches to overcome this challenge include identification of novel targets for discovery of new antibiotics. Bacterial topoisomerase I is present in all bacterial pathogens as a potential target for bactericidal topoisomerase poison inhibitors. Recent efforts have identified inhibitors of bacterial topoisomerase I with antibacterial activity. Additional research on the mode of action and binding site of these inhibitors would provide further validation of the target and establish that bacterial topoisomerase I is druggable. Bacterial topoisomerase I is a potentially high value target for discovery of new antibiotics. Demonstration of topoisomerase I as the cellular target of an antibacterial compound would provide proof-of-concept validation.
Collapse
|
14
|
Kern G, Palmer T, Ehmann DE, Shapiro AB, Andrews B, Basarab GS, Doig P, Fan J, Gao N, Mills SD, Mueller J, Sriram S, Thresher J, Walkup GK. Inhibition of Neisseria gonorrhoeae Type II Topoisomerases by the Novel Spiropyrimidinetrione AZD0914. J Biol Chem 2015; 290:20984-20994. [PMID: 26149691 DOI: 10.1074/jbc.m115.663534] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 11/06/2022] Open
Abstract
We characterized the inhibition of Neisseria gonorrhoeae type II topoisomerases gyrase and topoisomerase IV by AZD0914 (AZD0914 will be henceforth known as ETX0914 (Entasis Therapeutics)), a novel spiropyrimidinetrione antibacterial compound that is currently in clinical trials for treatment of drug-resistant gonorrhea. AZD0914 has potent bactericidal activity against N. gonorrhoeae, including multidrug-resistant strains and key Gram-positive, fastidious Gram-negative, atypical, and anaerobic bacterial species (Huband, M. D., Bradford, P. A., Otterson, L. G., Basrab, G. S., Giacobe, R. A., Patey, S. A., Kutschke, A. C., Johnstone, M. R., Potter, M. E., Miller, P. F., and Mueller, J. P. (2014) In Vitro Antibacterial Activity of AZD0914: A New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-positive, Fastidious Gram-negative, and Atypical Bacteria. Antimicrob. Agents Chemother. 59, 467-474). AZD0914 inhibited DNA biosynthesis preferentially to other macromolecules in Escherichia coli and induced the SOS response to DNA damage in E. coli. AZD0914 stabilized the enzyme-DNA cleaved complex for N. gonorrhoeae gyrase and topoisomerase IV. The potency of AZD0914 for inhibition of supercoiling and the stabilization of cleaved complex by N. gonorrhoeae gyrase increased in a fluoroquinolone-resistant mutant enzyme. When a mutation, conferring mild resistance to AZD0914, was present in the fluoroquinolone-resistant mutant, the potency of ciprofloxacin for inhibition of supercoiling and stabilization of cleaved complex was increased greater than 20-fold. In contrast to ciprofloxacin, religation of the cleaved DNA did not occur in the presence of AZD0914 upon removal of magnesium from the DNA-gyrase-inhibitor complex. AZD0914 had relatively low potency for inhibition of human type II topoisomerases α and β.
Collapse
Affiliation(s)
- Gunther Kern
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451.
| | - Tiffany Palmer
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - David E Ehmann
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Adam B Shapiro
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Beth Andrews
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Gregory S Basarab
- Departments of Chemistry, Infection Innovative Medicines Unit, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Peter Doig
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Jun Fan
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Ning Gao
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Scott D Mills
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - John Mueller
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Shubha Sriram
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Jason Thresher
- Department of Structure and Biophysics, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| | - Grant K Walkup
- Departments of Biosciences, Discovery Sciences, AstraZeneca R&D Boston, Waltham, Massachusetts 02451
| |
Collapse
|
15
|
Cheng B, Annamalai T, Sandhaus S, Bansod P, Tse-Dinh YC. Inhibition of Zn(II) binding type IA topoisomerases by organomercury compounds and Hg(II). PLoS One 2015; 10:e0120022. [PMID: 25798600 PMCID: PMC4370478 DOI: 10.1371/journal.pone.0120022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/18/2015] [Indexed: 11/19/2022] Open
Abstract
Type IA topoisomerase activities are essential for resolving DNA topological barriers via an enzyme-mediated transient single strand DNA break. Accumulation of topoisomerase DNA cleavage product can lead to cell death or genomic rearrangement. Many antibacterial and anticancer drugs act as topoisomerase poison inhibitors that form stabilized ternary complexes with the topoisomerase covalent intermediate, so it is desirable to identify such inhibitors for type IA topoisomerases. Here we report that organomercury compounds were identified during a fluorescence based screening of the NIH diversity set of small molecules for topoisomerase inhibitors that can increase the DNA cleavage product of Yersinia pestis topoisomerase I. Inhibition of relaxation activity and accumulation of DNA cleavage product were confirmed for these organomercury compounds in gel based assays of Escherichia coli topoisomerase I. Hg(II), but not As(III), could also target the cysteines that form the multiple Zn(II) binding tetra-cysteine motifs found in the C-terminal domains of these bacterial topoisomerase I for relaxation activity inhibition. Mycobacterium tuberculosis topoisomerase I activity is not sensitive to Hg(II) or the organomercury compounds due to the absence of the Zn(II) binding cysteines. It is significant that the type IA topoisomerases with Zn(II) binding domains can still cleave DNA when interfered by Hg(II) or organomercury compounds. The Zn(II) binding domains found in human Top3α and Top3β may be potential targets of toxic metals and organometallic complexes, with potential consequence on genomic stability and development.
Collapse
Affiliation(s)
- Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, United States of America
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Shayna Sandhaus
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Priyanka Bansod
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
- Biomolecular Sciences Institute, Florida International University, Miami, Florida, United States of America
- * E-mail:
| |
Collapse
|
16
|
Opposing effects of target overexpression reveal drug mechanisms. Nat Commun 2014; 5:4296. [PMID: 24980690 DOI: 10.1038/ncomms5296] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 06/03/2014] [Indexed: 12/15/2022] Open
Abstract
Overexpression of a drug's molecular target often increases drug resistance, offering a pathway for adaptive evolution and a tool for target identification. It is unclear though why this phenomenon applies to some drugs but not others. Here we gradually overexpressed antibiotic targets in Escherichia coli and found that drug resistance can increase, remain unchanged, decrease or even change non-monotonically. Even a single target can produce opposing responses to its different inhibitors. We explain these contradicting effects with quantitative models of enzyme inhibition that account for fitness costs and the biochemical activity or inactivity of drug-enzyme complexes. Thus, target overexpression confers resistance or sensitivity as a predictable property of drug mechanism, explaining its variable presence in nature as a resistance mechanism. Though overexpression screens may fail at identifying unknown targets, overexpressing known or putative targets provides a systematic approach to distinguish between simple inhibition and complex mechanisms of drug action.
Collapse
|
17
|
Kiianitsa K, Maizels N. Ultrasensitive isolation, identification and quantification of DNA-protein adducts by ELISA-based RADAR assay. Nucleic Acids Res 2014; 42:e108. [PMID: 24914050 PMCID: PMC4117749 DOI: 10.1093/nar/gku490] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Enzymes that form transient DNA-protein covalent complexes are targets for several potent classes of drugs used to treat infectious disease and cancer, making it important to establish robust and rapid procedures for analysis of these complexes. We report a method for isolation of DNA-protein adducts and their identification and quantification, using techniques compatible with high-throughput screening. This method is based on the RADAR assay for DNA adducts that we previously developed (Kiianitsa and Maizels (2013) A rapid and sensitive assay for DNA-protein covalent complexes in living cells. Nucleic Acids Res., 41:e104), but incorporates three key new steps of broad applicability. (i) Silica-assisted ethanol/isopropanol precipitation ensures reproducible and efficient recovery of DNA and DNA-protein adducts at low centrifugal forces, enabling cell culture and DNA precipitation to be carried out in a single microtiter plate. (ii) Rigorous purification of DNA-protein adducts by a procedure that eliminates free proteins and free nucleic acids, generating samples suitable for detection of novel protein adducts (e.g. by mass spectroscopy). (iii) Identification and quantification of DNA-protein adducts by direct ELISA assay. The ELISA-based RADAR assay can detect Top1-DNA and Top2a-DNA adducts in human cells, and gyrase-DNA adducts in Escherichia coli. This approach will be useful for discovery and characterization of new drugs to treat infectious disease and cancer, and for development of companion diagnostics assays for individualized medicine.
Collapse
Affiliation(s)
| | - Nancy Maizels
- Department of Immunology, University of Washington, Seattle, WA 98195, USA Department of Biochemistry, University of Washington, Seattle, WA 98195, USA Department of Pathology, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
18
|
Abstract
![]()
Quinolones
are one of the most commonly prescribed classes of antibacterials
in the world and are used to treat a variety of bacterial infections
in humans. Because of the wide use (and overuse) of these drugs, the
number of quinolone-resistant bacterial strains has been growing steadily
since the 1990s. As is the case with other antibacterial agents, the
rise in quinolone resistance threatens the clinical utility of this
important drug class. Quinolones act by converting their targets,
gyrase and topoisomerase IV, into toxic enzymes that fragment the
bacterial chromosome. This review describes the development of the
quinolones as antibacterials, the structure and function of gyrase
and topoisomerase IV, and the mechanistic basis for quinolone action
against their enzyme targets. It will then discuss the following three
mechanisms that decrease the sensitivity of bacterial cells to quinolones.
Target-mediated resistance is the most common and clinically significant
form of resistance. It is caused by specific mutations in gyrase and
topoisomerase IV that weaken interactions between quinolones and these
enzymes. Plasmid-mediated resistance results from extrachromosomal
elements that encode proteins that disrupt quinolone–enzyme
interactions, alter drug metabolism, or increase quinolone efflux.
Chromosome-mediated resistance results from the underexpression of
porins or the overexpression of cellular efflux pumps, both of which
decrease cellular concentrations of quinolones. Finally, this review
will discuss recent advancements in our understanding of how quinolones
interact with gyrase and topoisomerase IV and how mutations in these
enzymes cause resistance. These last findings suggest approaches to
designing new drugs that display improved activity against resistant
strains.
Collapse
Affiliation(s)
- Katie J Aldred
- Department of Biochemistry and ‡Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
| | | | | |
Collapse
|
19
|
Mustaev A, Malik M, Zhao X, Kurepina N, Luan G, Oppegard LM, Hiasa H, Marks KR, Kerns RJ, Berger JM, Drlica K. Fluoroquinolone-gyrase-DNA complexes: two modes of drug binding. J Biol Chem 2014; 289:12300-12. [PMID: 24497635 DOI: 10.1074/jbc.m113.529164] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA gyrase and topoisomerase IV control bacterial DNA topology by breaking DNA, passing duplex DNA through the break, and then resealing the break. This process is subject to reversible corruption by fluoroquinolones, antibacterials that form drug-enzyme-DNA complexes in which the DNA is broken. The complexes, called cleaved complexes because of the presence of DNA breaks, have been crystallized and found to have the fluoroquinolone C-7 ring system facing the GyrB/ParE subunits. As expected from x-ray crystallography, a thiol-reactive, C-7-modified chloroacetyl derivative of ciprofloxacin (Cip-AcCl) formed cross-linked cleaved complexes with mutant GyrB-Cys(466) gyrase as evidenced by resistance to reversal by both EDTA and thermal treatments. Surprisingly, cross-linking was also readily seen with complexes formed by mutant GyrA-G81C gyrase, thereby revealing a novel drug-gyrase interaction not observed in crystal structures. The cross-link between fluoroquinolone and GyrA-G81C gyrase correlated with exceptional bacteriostatic activity for Cip-AcCl with a quinolone-resistant GyrA-G81C variant of Escherichia coli and its Mycobacterium smegmatis equivalent (GyrA-G89C). Cip-AcCl-mediated, irreversible inhibition of DNA replication provided further evidence for a GyrA-drug cross-link. Collectively these data establish the existence of interactions between the fluoroquinolone C-7 ring and both GyrA and GyrB. Because the GyrA-Gly(81) and GyrB-Glu(466) residues are far apart (17 Å) in the crystal structure of cleaved complexes, two modes of quinolone binding must exist. The presence of two binding modes raises the possibility that multiple quinolone-enzyme-DNA complexes can form, a discovery that opens new avenues for exploring and exploiting relationships between drug structure and activity with type II DNA topoisomerases.
Collapse
Affiliation(s)
- Arkady Mustaev
- From the Public Health Research Institute and Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey 07103
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
SbcCD-mediated processing of covalent gyrase-DNA complex in Escherichia coli. Antimicrob Agents Chemother 2013; 57:5116-9. [PMID: 23917316 DOI: 10.1128/aac.00130-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Quinolones trap the covalent gyrase-DNA complex in Escherichia coli, leading to cell death. Processing activities for trapped covalent complex have not been characterized. A mutant strain lacking SbcCD nuclease activity was examined for both accumulation of gyrase-DNA complex and viability after quinolone treatment. Higher complex levels were found in ΔsbcCD cells than in wild-type cells after incubation with nalidixic acid and ciprofloxacin. However, SbcCD activity protected cells against the bactericidal action of nalidixic acid but not ciprofloxacin.
Collapse
|
21
|
Zhang H, Guo J, Li D, Ng MTT, Lee JY, Lv B, Ng CW, Lee S, Shao F, Li T. Confirmation of quinolone-induced formation of gyrase–DNA conjugates using AFM. Bioorg Med Chem Lett 2013; 23:4622-6. [DOI: 10.1016/j.bmcl.2013.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 05/29/2013] [Accepted: 06/10/2013] [Indexed: 11/28/2022]
|