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Bibi Z, Asghar I, Ashraf NM, Zeb I, Rashid U, Hamid A, Ali MK, Hatamleh AA, Al-Dosary MA, Ahmad R, Ali M. Prediction of Phytochemicals for Their Potential to Inhibit New Delhi Metallo β-Lactamase (NDM-1). Pharmaceuticals (Basel) 2023; 16:1404. [PMID: 37895875 PMCID: PMC10610165 DOI: 10.3390/ph16101404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/18/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
The effectiveness of all antibiotics in the β-lactam group to cure bacterial infections has been impaired by the introduction of the New Delhi Metallo-β-lactamase (NDM-1) enzyme. Attempts have been made to discover a potent chemical as an inhibitor to this enzyme in order to restore the efficacy of antibiotics. However, it has been a challenging task to develop broad-spectrum inhibitors of metallo-β-lactamases. Lack of sequence homology across metallo-β-lactamases (MBLs), the rapidly evolving active site of the enzyme, and structural similarities between human enzymes and metallo-β-lactamases, are the primary causes for the difficulty in the development of these inhibitors. Therefore, it is imperative to concentrate on the discovery of an effective NDM-1 inhibitor. This study used various in silico approaches, including molecular docking and molecular dynamics simulations, to investigate the potential of phytochemicals to inhibit the NDM-1 enzyme. For this purpose, a library of about 59,000 phytochemicals was created from the literature and other databases, including FoodB, IMPPAT, and Phenol-Explorer. A physiochemical and pharmacokinetics analysis was performed to determine possible toxicity and mutagenicity of the ligands. Following the virtual screening, phytochemicals were assessed for their binding with NDM-1using docking scores, RMSD values, and other critical parameters. The docking score was determined by selecting the best conformation of the protein-ligand complex. Three phytochemicals, i.e., butein (polyphenol), monodemethylcurcumin (polyphenol), and rosmarinic acid (polyphenol) were identified as result of pharmacokinetics and molecular docking studies. Furthermore, molecular dynamics simulations were performed to determine structural stabilities of the protein-ligand complexes. Monodemethylcurcumin, butein, and rosmarinic acid were identified as potential inhibitors of NDM-1 based on their low RMSD, RMSF, hydrogen bond count, average Coulomb-Schrödinger interaction energy, and Lennard-Jones-Schrödinger interaction energy. The present investigation suggested that these phytochemicals might be promising candidates for future NDM-1 medication development to respond to antibiotic resistance.
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Affiliation(s)
- Zainab Bibi
- Department of Biotechnology, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan (R.A.)
| | - Irfa Asghar
- Department of Biotechnology, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan (R.A.)
| | - Naeem Mahmood Ashraf
- School of Biochemistry and Biotechnology, University of Punjab, Lahore P.O. Box 54590, Pakistan;
| | - Iftikhar Zeb
- Department of Biotechnology, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan (R.A.)
| | - Umer Rashid
- Department of Chemistry, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan;
| | - Arslan Hamid
- LIMES Institute, University of Bonn, D-53113 Bonn, Germany;
| | - Maria Kanwal Ali
- Institute of Nuclear Medicine, Oncology and Radiotherapy (INOR), Abbottabad 22060, Pakistan;
| | - Ashraf Atef Hatamleh
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (A.A.H.); (M.A.A.-D.)
| | - Munirah Abdullah Al-Dosary
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (A.A.H.); (M.A.A.-D.)
| | - Raza Ahmad
- Department of Biotechnology, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan (R.A.)
| | - Muhammad Ali
- Department of Biotechnology, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan (R.A.)
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Ishikawa T, Furukawa N, Caselli E, Prati F, Taracila MA, Bethel CR, Ishii Y, Shimizu-Ibuka A, Bonomo RA. Insights Into the Inhibition of MOX-1 β-Lactamase by S02030, a Boronic Acid Transition State Inhibitor. Front Microbiol 2022; 12:720036. [PMID: 34970229 PMCID: PMC8713471 DOI: 10.3389/fmicb.2021.720036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 11/12/2021] [Indexed: 11/13/2022] Open
Abstract
The rise of multidrug resistant (MDR) Gram-negative bacteria has accelerated the development of novel inhibitors of class A and C β-lactamases. Presently, the search for novel compounds with new mechanisms of action is a clinical and scientific priority. To this end, we determined the 2.13-Å resolution crystal structure of S02030, a boronic acid transition state inhibitor (BATSI), bound to MOX-1 β-lactamase, a plasmid-borne, expanded-spectrum AmpC β-lactamase (ESAC) and compared this to the previously reported aztreonam (ATM)-bound MOX-1 structure. Superposition of these two complexes shows that S02030 binds in the active-site cavity more deeply than ATM. In contrast, the SO3 interactions and the positional change of the β-strand amino acids from Lys315 to Asn320 were more prominent in the ATM-bound structure. MICs were performed using a fixed concentration of S02030 (4 μg/ml) as a proof of principle. Microbiological evaluation against a laboratory strain of Escherichia coli expressing MOX-1 revealed that MICs against ceftazidime are reduced from 2.0 to 0.12 μg/ml when S02030 is added at a concentration of 4 μg/ml. The IC50 and Ki of S02030 vs. MOX-1 were 1.25 ± 0.34 and 0.56 ± 0.03 μM, respectively. Monobactams such as ATM can serve as informative templates for design of mechanism-based inhibitors such as S02030 against ESAC β-lactamases.
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Affiliation(s)
- Tatsuya Ishikawa
- Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | | | - Emilia Caselli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Fabio Prati
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Magdalena A Taracila
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States.,Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Christopher R Bethel
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States
| | - Yoshikazu Ishii
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan
| | - Akiko Shimizu-Ibuka
- Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Robert A Bonomo
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States.,Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Departments of Pharmacology, Molecular Biology and Microbiology, Biochemistry, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH, United States
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Xu Q, Hu X, Wang Y. Alternatives to Conventional Antibiotic Therapy: Potential Therapeutic Strategies of Combating Antimicrobial-Resistance and Biofilm-Related Infections. Mol Biotechnol 2021; 63:1103-1124. [PMID: 34309796 DOI: 10.1007/s12033-021-00371-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/08/2021] [Indexed: 12/14/2022]
Abstract
Antibiotics have been denoted as the orthodox therapeutic agents for fighting bacteria-related infections in clinical practices for decades. Nevertheless, overuse of antibiotics has led to the upsurge of species with antimicrobial resistance (AMR) or multi-drug resistance. Bacteria can also grow into the biofilm, which accounts for at least two-thirds of infections. Distinct gene expression and self-produced heterogeneous hydrated extracellular polymeric substance matrix architecture of biofilm contribute to their tolerance and externally manifest as antibiotic resistance. In this review, the difficulties in combating biofilm formation and AMR are introduced, and novel alternatives to antibiotics such as metal nanoparticles and quaternary ammonium compounds, chitosan and its derivatives, antimicrobial peptides, stimuli-responsive materials, phage therapy and other therapeutic strategies, from compounds to hydrogel, from inorganic to biological, are discussed. We expect to provide useful information for the readers who are seeking for solutions to the problem of AMR and biofilm-related infections.
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Affiliation(s)
- Qian Xu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China
| | - Xuefeng Hu
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China.
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, Sichuan, People's Republic of China.
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Chandler JC, Anders JE, Blouin NA, Carlson JC, LeJeune JT, Goodridge LD, Wang B, Day LA, Mangan AM, Reid DA, Coleman SM, Hopken MW, Bisha B. The Role of European Starlings (Sturnus vulgaris) in the Dissemination of Multidrug-Resistant Escherichia coli among Concentrated Animal Feeding Operations. Sci Rep 2020; 10:8093. [PMID: 32415136 PMCID: PMC7229194 DOI: 10.1038/s41598-020-64544-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 04/16/2020] [Indexed: 12/29/2022] Open
Abstract
Antimicrobial use in livestock production is a driver for the development and proliferation of antimicrobial resistance (AMR). Wildlife interactions with livestock, acquiring associated AMR bacteria and genes, and wildlife's subsequent dispersal across the landscape are hypothesized to play an important role in the ecology of AMR. Here, we examined priority AMR phenotypes and genotypes of Escherichia coli isolated from the gastrointestinal tracts of European starlings (Sturnus vulgaris) found on concentrated animal feeding operations (CAFOs). European starlings may be present in high numbers on CAFOs (>100,000 birds), interact with urban environments, and can migrate distances exceeding 1,500 km in North America. In this study, 1,477 European starlings from 31 feedlots in five U.S. states were sampled for E. coli resistant to third generation cephalosporins (3G-C) and fluoroquinolones. The prevalence of 3G-C and fluoroquinolone-resistant E. coli was 4% and 10%, respectively. Multidrug resistance in the E. coli isolates collected (n = 236) was common, with the majority of isolates displaying resistance to six or more classes of antibiotics. Genetic analyses of a subset of these isolates identified 94 genes putatively contributing to AMR, including seven class A and C β-lactamases as well as mutations in gyrA and parC recognized to confer resistance to quinolones. Phylogenetic and subtyping assessments showed that highly similar isolates (≥99.4% shared core genome, ≥99.6% shared coding sequence) with priority AMR were found in birds on feedlots separated by distances exceeding 150 km, suggesting that European starlings could be involved in the interstate dissemination of priority AMR bacteria.
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Affiliation(s)
- Jeffrey C Chandler
- U.S. Department of Agriculture, National Wildlife Research Center, Fort Collins, CO, USA
| | - Jennifer E Anders
- University of Wyoming, Department of Animal Science, Laramie, WY, USA
| | - Nicolas A Blouin
- University of Wyoming, Department of Molecular Biology, Laramie, WY, USA
| | - James C Carlson
- U.S. Department of Agriculture, National Wildlife Research Center, Fort Collins, CO, USA
| | - Jeffrey T LeJeune
- Food and Agriculture Organization of the United Nations, Rome, Italy
| | | | - Baolin Wang
- University of Wyoming, Department of Animal Science, Laramie, WY, USA
| | - Leslie A Day
- University of Wyoming, Department of Animal Science, Laramie, WY, USA
| | - Anna M Mangan
- U.S. Department of Agriculture, National Wildlife Research Center, Fort Collins, CO, USA
| | - Dustin A Reid
- U.S. Department of Agriculture, National Wildlife Research Center, Fort Collins, CO, USA
| | - Shannon M Coleman
- Iowa State University, Department of Food Science and Human Nutrition, Ames, IA, USA
| | - Matthew W Hopken
- Colorado State University, Department of Microbiology, Immunology, and Pathology, Fort Collins, CO, USA
| | - Bledar Bisha
- University of Wyoming, Department of Animal Science, Laramie, WY, USA.
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Oligoribonuclease Contributes to Tolerance to Aminoglycoside and β-Lactam Antibiotics by Regulating KatA in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2019; 63:AAC.00212-19. [PMID: 30936107 DOI: 10.1128/aac.00212-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 03/29/2019] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen and is intrinsically resistant to a variety of antibiotics. Oligoribonuclease (Orn) is a 3'-to-5' exonuclease that degrades nanoRNAs. The Orn controls biofilm formation by influencing the homeostasis of cyclic-di-GMP. Previously, we demonstrated that Orn contributes to the tolerance of P. aeruginosa to fluoroquinolone antibiotics by affecting the production of pyocins. In this study, we found that mutation in the orn gene reduces bacterial tolerance to aminoglycoside and β-lactam antibiotics, which is mainly due to a defective response to oxidative stresses. The major catalase KatA is downregulated in the orn mutant, and overexpression of the katA gene restores the bacterial tolerance to oxidative stresses and the antibiotics. We further demonstrated that Orn influenced the translation of the katA mRNA and narrowed down the region in the katA mRNA that is involved in the regulation of its translation. Therefore, our results revealed a novel role of the Orn in bacterial tolerance to oxidative stresses as well as aminoglycoside and β-lactam antibiotics.
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6
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Insight into the catalytic hydrolysis mechanism of New Delhi metallo-β-lactamase to aztreonam by molecular modeling. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Modified Penicillin Molecule with Carbapenem-Like Stereochemistry Specifically Inhibits Class C β-Lactamases. Antimicrob Agents Chemother 2017; 61:AAC.01288-17. [PMID: 28971874 DOI: 10.1128/aac.01288-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/19/2017] [Indexed: 11/20/2022] Open
Abstract
Bacterial β-lactamases readily inactivate most penicillins and cephalosporins by hydrolyzing and "opening" their signature β-lactam ring. In contrast, carbapenems resist hydrolysis by many serine-based class A, C, and D β-lactamases due to their unique stereochemical features. To improve the resistance profile of penicillins, we synthesized a modified penicillin molecule, MPC-1, by "grafting" carbapenem-like stereochemistry onto the penicillin core. Chemical modifications include the trans conformation of hydrogen atoms at C-5 and C-6 instead of cis, and a 6-α hydroxyethyl moiety to replace the original 6-β aminoacyl group. MPC-1 selectively inhibits class C β-lactamases, such as P99, by forming a nonhydrolyzable acyl adduct, and its inhibitory potency is ∼2 to 5 times higher than that for clinically used β-lactamase inhibitors clavulanate and sulbactam. The crystal structure of MPC-1 forming the acyl adduct with P99 reveals a novel binding mode for MPC-1 that resembles carbapenem bound in the active site of class A β-lactamases. Furthermore, in this novel binding mode, the carboxyl group of MPC-1 blocks the deacylation reaction by occluding the critical catalytic water molecule and renders the acyl adduct nonhydrolyzable. Our results suggest that by incorporating carbapenem-like stereochemistry, the current collection of over 100 penicillins and cephalosporins can be modified into candidate compounds for development of novel β-lactamase inhibitors.
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González-Bello C. Designing Irreversible Inhibitors-Worth the Effort? ChemMedChem 2015; 11:22-30. [DOI: 10.1002/cmdc.201500469] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Indexed: 12/29/2022]
Affiliation(s)
- Concepción González-Bello
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS); Universidade de Santiago de Compostela; calle Jenaro de la Fuente s/n Santiago de Compostela 15782 Spain
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Hazra S, Kurz SG, Wolff K, Nguyen L, Bonomo RA, Blanchard JS. Kinetic and Structural Characterization of the Interaction of 6-Methylidene Penem 2 with the β-Lactamase from Mycobacterium tuberculosis. Biochemistry 2015; 54:5657-64. [PMID: 26237118 DOI: 10.1021/acs.biochem.5b00698] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis is intrinsically resistant to most β-lactam antibiotics because of the constitutive expression of the blaC-encoded β-lactamase. This enzyme has extremely high activity against penicillins and cephalosporins, but weaker activity against carbapenems. The enzyme can be inhibited by clavulanate, avibactam, and boronic acids. In this study, we investigated the ability of 6-methylidene β-lactams to inhibit BlaC. One such compound, penem 2, inhibited BlaC more than 70 times more efficiently than clavulanate. The compound forms a covalent complex with BlaC as shown by mass spectrometry. Crystallization of the complex revealed that the bound inhibitor was covalently attached via the Ser70 active site residue and that the covalently, acylated form of the inhibitor had undergone additional chemistry yielding a 4,7-thiazepine ring in place of the β-lactam and a thiazapyroline ring generated as a result of β-lactam ring opening. The stereochemistry of the product of the 7-endo-trig cyclization was the opposite of that observed previously for class A and D β-lactamases. Addition of penem 2 greatly synergized the antibacterial properties of both ampicillin and meropenem against a growing culture of M. tuberculosis. Strikingly, penem 2 alone showed significant growth inhibition, suggesting that in addition to its capability of efficiently inhibiting BlaC, it also inhibited the peptidoglycan cross-linking transpeptidases.
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Affiliation(s)
- Saugata Hazra
- Department of Biotechnology, Indian Institute of Technology, Roorkee , Roorkee, Uttarakhand 247667, India
| | - Sebastian G Kurz
- Tufts University School of Medicine , 800 Washington Street, #257, Boston, Massachusetts 02111, United States
| | - Kerstin Wolff
- Early Discovery, Infectious Diseases Antibacterial & Antifungal, Merck Research Laboratories , Kenilworth, New Jersey 07033, United States
| | | | - Robert A Bonomo
- Department of Medicine, Louis Stokes Cleveland Veterans Affairs Medical Center , Cleveland, Ohio 44106, United States
| | - John S Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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Mehta SC, Rice K, Palzkill T. Natural Variants of the KPC-2 Carbapenemase have Evolved Increased Catalytic Efficiency for Ceftazidime Hydrolysis at the Cost of Enzyme Stability. PLoS Pathog 2015; 11:e1004949. [PMID: 26030609 PMCID: PMC4452179 DOI: 10.1371/journal.ppat.1004949] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/11/2015] [Indexed: 02/07/2023] Open
Abstract
The spread of β-lactamases that hydrolyze penicillins, cephalosporins and carbapenems among Gram-negative bacteria has limited options for treating bacterial infections. Initially, Klebsiella pneumoniae carbapenemase-2 (KPC-2) emerged as a widespread carbapenem hydrolyzing β-lactamase that also hydrolyzes penicillins and cephalosporins but not cephamycins and ceftazidime. In recent years, single and double amino acid substitution variants of KPC-2 have emerged among clinical isolates that show increased resistance to ceftazidime. Because it confers multi-drug resistance, KPC β-lactamase is a threat to public health. In this study, the evolution of KPC-2 function was determined in nine clinically isolated variants by examining the effects of the substitutions on enzyme kinetic parameters, protein stability and antibiotic resistance profile. The results indicate that the amino acid substitutions associated with KPC-2 natural variants lead to increased catalytic efficiency for ceftazidime hydrolysis and a consequent increase in ceftazidime resistance. Single substitutions lead to modest increases in catalytic activity while the double mutants exhibit significantly increased ceftazidime hydrolysis and resistance levels. The P104R, V240G and H274Y substitutions in single and double mutant combinations lead to the largest increases in ceftazidime hydrolysis and resistance. Molecular modeling suggests that the P104R and H274Y mutations could facilitate ceftazidime hydrolysis through increased hydrogen bonding interactions with the substrate while the V240G substitution may enhance backbone flexibility so that larger substrates might be accommodated in the active site. Additionally, we observed a strong correlation between gain of catalytic function for ceftazidime hydrolysis and loss of enzyme stability, which is in agreement with the ‘stability-function tradeoff’ phenomenon. The high Tm of KPC-2 (66.5°C) provides an evolutionary advantage as compared to other class A enzymes such as TEM (51.5°C) and CTX-M (51°C) in that it can acquire multiple destabilizing substitutions without losing the ability to fold into a functional enzyme. The absence of new antibiotics combined with the emergence of antibiotic-resistance enzymes like KPC-2 that can inactivate most β-lactam antibiotics has resulted in a longer duration of medical treatment, higher costs of medical care, and increased mortality. In recent years, a number of amino acid sequence variants of KPC-2 have been identified in clinical isolates worldwide suggesting continued evolution of resistance in KPC-2. In this study we have characterized nine clinically isolated variants of KPC-2 (KPC-3 to -11) that differ from the initial KPC-2 isolate by one to two amino acids. The KPC variants confer increased resistance to the antibiotic ceftazidime as compared to KPC-2. This increase in resistance is correlated with improved ability of the variant enzymes to hydrolyze the antibiotic. Additionally, the changes associated with increased ceftazidime hydrolysis also reduce the thermal stability of the enzyme, indicating the mutations that assist catalysis come with a cost on the overall stability of the enzyme. The high thermal stability of KPC-2 allows destabilizing mutations that enhance catalysis to accumulate while the enzyme retains a folded, functional structure. Thus, the high stability of KPC-2 provides an evolutionary advantage to acquire multiple mutations and retain function as compared to other β-lactamase enzymes.
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Affiliation(s)
- Shrenik C. Mehta
- Department of Pharmacology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kacie Rice
- Department of Pharmacology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Timothy Palzkill
- Department of Pharmacology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Structural basis for carbapenem-hydrolyzing mechanisms of carbapenemases conferring antibiotic resistance. Int J Mol Sci 2015; 16:9654-92. [PMID: 25938965 PMCID: PMC4463611 DOI: 10.3390/ijms16059654] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 02/06/2023] Open
Abstract
Carbapenems (imipenem, meropenem, biapenem, ertapenem, and doripenem) are β-lactam antimicrobial agents. Because carbapenems have the broadest spectra among all β-lactams and are primarily used to treat infections by multi-resistant Gram-negative bacteria, the emergence and spread of carbapenemases became a major public health concern. Carbapenemases are the most versatile family of β-lactamases that are able to hydrolyze carbapenems and many other β-lactams. According to the dependency of divalent cations for enzyme activation, carbapenemases can be divided into metallo-carbapenemases (zinc-dependent class B) and non-metallo-carbapenemases (zinc-independent classes A, C, and D). Many studies have provided various carbapenemase structures. Here we present a comprehensive and systematic review of three-dimensional structures of carbapenemase-carbapenem complexes as well as those of carbapenemases. We update recent studies in understanding the enzymatic mechanism of each class of carbapenemase, and summarize structural insights about regions and residues that are important in acquiring the carbapenemase activity.
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Gholipour A, Soleimani N, Shokri D, Mobasherizadeh S, Kardi M, Baradaran A. Phenotypic and Molecular Characterization of Extended-Spectrum β-Lactamase Produced by Escherichia coli, and Klebsiella pneumoniae Isolates in an Educational Hospital. Jundishapur J Microbiol 2014; 7:e11758. [PMID: 25632322 PMCID: PMC4295312 DOI: 10.5812/jjm.11758] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/04/2013] [Accepted: 09/08/2014] [Indexed: 11/16/2022] Open
Abstract
Background: Extended-spectrum beta-lactamases (ESBLs) are a group of enzymes that hydrolyze antibiotics, including those containing new cephalosporins, and they are found in a significant percentage of Escherichia coli and Klebsiellapneumoniae strains. With the widespread use of antibiotics, difficulties with infection therapy caused by drug resistant organisms, especially those that have acquired resistance to beta-lactams, such as broad-spectrum cephalosporins, have amplified the above-mentioned organisms. Objectives: This study was conducted to characterize ESBLs among E. coli and K. pneumonia isolates by molecular and phenotypic methods. Materials and Methods: Different strains of E. coli and K. pneumonia were collected from patients with urinary tract infections. The ESBL phenotype was determined by a double disk diffusion test (DDDT). In addition, polymerase chain reaction (PCR) analysis specific for β-lactamase genes of the TEM and SHV family was carried out. The PCR products were run on agarose and examined for DNA bands. Results: A total of 245 E. coli and 55 K. pneumonia strains were isolated from different samples. In total, 128 of the 300 isolates were confirmed as potential ESBLs producers as follows: 107 (43.67%) E. coli and 21 (38.18%) K. pneumonia. ESBLs genes were found in 24 isolates (18.75%): 21 E. coli and 3 K. pneumonia isolates. The TEM gene was present in 13 (12.14%) E. coli strains, but it was not detected in K. pneumonia. In addition, the SHV gene was present in 8 (7.47%) E. coli and 3 (14.28%) K. pneumonia isolates. Five (4.67%) of the E. coli isolates harbored both TEM and SHV genes. All isolates (100%) were susceptible to imipenem. The lowest rates of resistance to other antibiotics were observed for; piperacillin-tazobactam (6.25%), amikacin (12.5%) and gentamicin (14.84%). The rates of resistance to other antibiotics were as follow: nitrofurantoin (16.4%), nalidixic acid (23.43), co-trimoxazole (25%), cefepime (32%), ciprofloxacin (55.46%), ampicillin (69.53%), ceftazidime (100%), and cefotaxime (100%). Conclusions: The results of this study indicate the widespread prevalence of ESBLs and multiple antibiotic resistance in E. coli and K. pneumoniae. Therefore, beta-lactam antibiotics and beta-lactamase inhibitors or carbapenems should be prescribed based on an antibacterial susceptibility test.
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Affiliation(s)
- Abolfazl Gholipour
- Department of Microbiology and Immunology, Cellular and Molecular Research center, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, IR Iran
| | - Neda Soleimani
- Department of Pathology, Al-Zahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Dariush Shokri
- Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Sina Mobasherizadeh
- Department of Microbiology, Al-Zahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Mohammad Kardi
- Department of Pathology, Al-Zahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Azar Baradaran
- Department of Pathology, Al-Zahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran
- Corresponding author: Azar Baradaran, Department of Pathology, Al-Zahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran. Tel: +98-3116691565, Fax: +98-3116684510, E-mail:
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Pan X, Wong WT, He Y, Jiang Y, Zhao Y. Perturbing the general base residue Glu166 in the active site of class A β-lactamase leads to enhanced carbapenem binding and acylation. Biochemistry 2014; 53:5414-23. [PMID: 25020031 DOI: 10.1021/bi401609h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Most class A β-lactamases cannot hydrolyze carbapenem antibiotics effectively. The molecular mechanism of this catalytic inefficiency has been attributed to the unique stereochemistry of carbapenems, including their 6-α-hydroxyethyl side chain and the transition between two tautomeric states when bound at the active site. Previous studies have shown that the 6-α-hydroxyethyl side chain of carbapenems can interfere with catalysis by forming hydrogen bonds with the deacylation water molecule to reduce its nucleophilicity. Here our studies of a class A noncarbapenemase PenP demonstrate that substituting the general base residue Glu166 with Ser or other residues leads to a significant enhancement of the acylation kinetics by ∼100-500 times toward carbapenems like meropenem. The structures of PenP and Glu166Ser both in apo form and in complex with meropenem reveal that Glu166 is critical for the formation of a hydrogen bonding network within the active site that locks Asn170 in an orientation to impose steric clash with the 6-α-hydroxyethyl side chain of meropenem. The Glu166Ser substitution weakens this network and enables Asn170 to adopt an alternative conformation to avoid steric clash and accommodate faster acylation kinetics. Furthermore, the weakened hydrogen bonding network caused by the Glu166Ser substitution allows the 6-α-hydroxyethyl moiety to adopt a catalytically favorable orientation as seen in class A carbapenemases. In summary, our data identify a previously unreported role of the universally conserved general base residue Glu166 in impeding the proper binding of carbapenems by restricting their 6-α-hydroxyethyl group.
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Affiliation(s)
- Xuehua Pan
- Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, P. R. China
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14
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Development of a multiplex real-time PCR for the rapid detection of the predominant beta-lactamase genes CTX-M, SHV, TEM and CIT-type AmpCs in Enterobacteriaceae. PLoS One 2014; 9:e100956. [PMID: 25033234 PMCID: PMC4102473 DOI: 10.1371/journal.pone.0100956] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/02/2014] [Indexed: 01/22/2023] Open
Abstract
Beta-lactamase resistant bacteria and especially ESBL producing Enterobacteriaceae are an increasing problem worldwide. For this reason a major interest in efficient and reliable methods for rapid screening of high sample numbers is recognizable. Therefore, a multiplex real-time PCR was developed to detect the predominant class A beta-lactamase genes blaCTX-M, blaSHV, blaTEM and CIT-type AmpCs in a one-step reaction. A set of 114 Enterobacteriaceae containing previously identified resistance gene subtypes and in addition 20 undefined animal and environmental isolates were used for the validation of this assay. To confirm the accessibility in variable settings, the real-time runs were performed analogous in two different laboratories using different real-time cyclers. The obtained results showed complete accordance between the real-time data and the predetermined genotypes. Even if sequence analyses are further necessary for a comprehensive characterization, this method was proofed to be reliable for rapid screening of high sample numbers and therefore could be an important tool for e. g. epidemiological purposes or support infection control measures.
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15
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Suárez CJ, Lolans K, Villegas MV, Quinn JP. Mechanisms of resistance to β-lactams in some common Gram-negative bacteria causing nosocomial infections. Expert Rev Anti Infect Ther 2014; 3:915-22. [PMID: 16307504 DOI: 10.1586/14787210.3.6.915] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Gram-negative bacilli remain major killers of hospitalized patients and continue to evolve new resistance mechanisms. This review describes the mechanisms of resistance to beta-lactam antibiotics from those Gram-negative pathogens most often isolated from nosocomial infections.
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Affiliation(s)
- Carlos José Suárez
- Bacterial Resistance Line, CIDEIM (International Center for Medical Research and Training), Cali, Colombia.
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16
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Skalweit Helfand M. β-lactams against emerging ‘superbugs’: progress and pitfalls. Expert Rev Clin Pharmacol 2014; 1:559-71. [DOI: 10.1586/17512433.1.4.559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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González LJ, Moreno DM, Bonomo RA, Vila AJ. Host-specific enzyme-substrate interactions in SPM-1 metallo-β-lactamase are modulated by second sphere residues. PLoS Pathog 2014; 10:e1003817. [PMID: 24391494 PMCID: PMC3879351 DOI: 10.1371/journal.ppat.1003817] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 10/21/2013] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is one of the most virulent and resistant non-fermenting Gram-negative pathogens in the clinic. Unfortunately, P. aeruginosa has acquired genes encoding metallo-β-lactamases (MβLs), enzymes able to hydrolyze most β-lactam antibiotics. SPM-1 is an MβL produced only by P. aeruginosa, while other MβLs are found in different bacteria. Despite similar active sites, the resistance profile of MβLs towards β-lactams changes from one enzyme to the other. SPM-1 is unique among pathogen-associated MβLs in that it contains “atypical” second sphere residues (S84, G121). Codon randomization on these positions and further selection of resistance-conferring mutants was performed. MICs, periplasmic enzymatic activity, Zn(II) requirements, and protein stability was assessed. Our results indicated that identity of second sphere residues modulates the substrate preferences and the resistance profile of SPM-1 expressed in P. aeruginosa. The second sphere residues found in wild type SPM-1 give rise to a substrate selectivity that is observed only in the periplasmic environment. These residues also allow SPM-1 to confer resistance in P. aeruginosa under Zn(II)-limiting conditions, such as those expected under infection. By optimizing the catalytic efficiency towards β-lactam antibiotics, the enzyme stability and the Zn(II) binding features, molecular evolution meets the specific needs of a pathogenic bacterial host by means of substitutions outside the active site. The presence of Zn(II)-containing metallo-β-lactamases (MβLs) that confer resistance to all penicillins, cephalosporins and carbapenems in Pseudomonas aeruginosa adds significantly to the threat of this pathogen in our health care system. SPM-1 is an MβLs widely distributed in South America and only found in P. aeruginosa. In common with all MβLs, the active site residues are highly conserved. In this work we asked the following question: how would substrate specificity evolve in SPM-1 if the active site residues are highly uniform and do not permit substitutions. To this end, we explored the role of two amino acids (S84 and G121) that are outside the active site (second sphere) and are unique in the SPM-1 β-lactamase. We discovered that replacing these amino acids impacts resistance to cephalosporins and carbapenems and that this resistance profile depends on the enzymatic behavior and the availability of Zn(II) in the environment. This work demonstrates how protein evolution by means of subtle substitutions outside the active site meets the specific needs of a pathogenic bacterial host.
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Affiliation(s)
- Lisandro J. González
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Diego M. Moreno
- Instituto de Química Rosario (IQUIR, CONICET-UNR), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center and Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio, United States of America
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- * E-mail:
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18
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Karsisiotis AI, Damblon CF, Roberts GCK. A variety of roles for versatile zinc in metallo-β-lactamases. Metallomics 2014; 6:1181-97. [DOI: 10.1039/c4mt00066h] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
β-Lactamases inactivate the important β-lactam antibiotics by catalysing the hydrolysis of the β-lactam ring, thus. One class of these enzymes, the metallo-β-lactamases, bind two zinc ions at the active site and these play important roles in the catalytic mechanism.
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Affiliation(s)
| | - C. F. Damblon
- Chimie Biologique Structurale
- Institut de Chimie
- Université de Liège
- 4000 Liège, Belgium
| | - G. C. K. Roberts
- The Henry Wellcome Laboratories of Structural Biology
- Department of Biochemistry
- University of Leicester
- Leicester LE1 9HN, UK
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19
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Allahverdiyev AM, Bagirova M, Abamor ES, Ates SC, Koc RC, Miraloglu M, Elcicek S, Yaman S, Unal G. The use of platensimycin and platencin to fight antibiotic resistance. Infect Drug Resist 2013; 6:99-114. [PMID: 24082790 PMCID: PMC3785399 DOI: 10.2147/idr.s25076] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Infectious diseases are known as one of the most life-threatening disabilities worldwide. Approximately 13 million deaths related to infectious diseases are reported each year. The only way to combat infectious diseases is by chemotherapy using antimicrobial agents and antibiotics. However, due to uncontrolled and unnecessary use of antibiotics in particular, surviving bacteria have evolved resistance against several antibiotics. Emergence of multidrug resistance in bacteria over the past several decades has resulted in one of the most important clinical health problems in modern medicine. For instance, approximately 440,000 new cases of multidrug-resistant tuberculosis are reported every year leading to the deaths of 150,000 people worldwide. Management of multidrug resistance requires understanding its molecular basis and the evolution and dissemination of resistance; development of new antibiotic compounds in place of traditional antibiotics; and innovative strategies for extending the life of antibiotic molecules. Researchers have begun to develop new antimicrobials for overcoming this important problem. Recently, platensimycin - isolated from extracts of Streptomyces platensis - and its analog platencin have been defined as promising agents for fighting multidrug resistance. In vitro and in vivo studies have shown that these new antimicrobials have great potential to inhibit methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae by targeting type II fatty acid synthesis in bacteria. Showing strong efficacy without any observed in vivo toxicity increases the significance of these antimicrobial agents for their use in humans. However, at the present time, clinical trials are insufficient and require more research. The strong antibacterial efficacies of platensimycin and platencin may be established in clinical trials and their use in humans for coping with multidrug resistance may be allowed in the foreseeable future.
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Affiliation(s)
| | - Melahat Bagirova
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
| | - Emrah Sefik Abamor
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
| | - Sezen Canim Ates
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
| | - Rabia Cakir Koc
- Department of Biomedical Engineering, Yeni Yuzyil University, Istanbul, Turkey
| | - Meral Miraloglu
- Vocational School of Health Services, Cukurova University, Adana, Turkey
| | - Serhat Elcicek
- Department of Bioengineering, Firat University, Elazig, Turkey
| | - Serkan Yaman
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
| | - Gokce Unal
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
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20
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Doudi M, Naghsh N, Setorki M. Comparison of the effects of silver nanoparticles on pathogenic bacteria resistant to beta-lactam antibiotics (ESBLs) as a prokaryote model and Wistar rats as a eukaryote model. Med Sci Monit Basic Res 2013; 19:103-10. [PMID: 23507904 PMCID: PMC3940702 DOI: 10.12659/msmbr.883835] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 08/15/2012] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Antimicrobial resistance in hospital pathogens is an important concern. It can cause longer hospital stays, increase costs, and contribute to increased mortality and morbidity in hospitalized patients. The aim of this study was to categorize and identify gram-negative bacilli capable of ESBLs production and to study the effect of MIC silver nanoparticles on bacteria strains and then study them in Wistar rats. MATERIAL AND METHODS A total of 186 clinical samples in 3 hospital of Isfahan city was studied during 8 months. The ESBL assay was performed by disk diffusion method. Minimum inhibitory concentration (MIC) values were determined by agar dilution method. Additionally, ESBLs production was examined by using the standard ESBL disc and DDT (double disk approximation test) procedures. Student's T-test and ANOVA were used for statistical analysis of the data. The ESBL-producing bacteria were then subjected to minimum concentrations of silver nanoparticles and then examined in Wistar rats. RESULTS Of the 186 patients studied, 140 (75.3%) had gram-negative bacilli containing ESBL and 46 (24.7%) had gram-negative bacilli without ESBL and the most prevalent bacteria was identified as Klebsiella pneumonia, with especially strong resistance to cefotaxime. All of these bacteria were sensitive to the silver nanoparticle solution with density of 100 ppm, but the 4 nm size did not show any significant difference from control group Wistar rats at 6 months. CONCLUSIONS The results seem to indicate a direct correlation between silver nanoparticle solution concentration and the diameter of growth zone for ESBL-producing bacteria. Assays in our study were in vitro; if use of silver nanoparticle particles in vivo proves to be with adverse effects, it could be a valuable alternative to antibiotics.
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Affiliation(s)
- Monir Doudi
- Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran
| | - Nooshin Naghsh
- Department of Biology, Falavarjan Branch, Islamic Azad University, Isfahan, Iran
| | - Mahbubeh Setorki
- Department of Biology, Izeh Branch, Islamic Azad University, Izeh, Iran
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21
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Heidari Torkabadi H, Che T, Shou J, Shanmugam S, Crowder MW, Bonomo RA, Pusztai-Carey M, Carey PR. Raman spectra of interchanging β-lactamase inhibitor intermediates on the millisecond time scale. J Am Chem Soc 2013; 135:2895-8. [PMID: 23406484 DOI: 10.1021/ja311440p] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rapid mix-rapid freeze is a powerful method to study the mechanisms of enzyme-substrate reactions in solution. Here we report a protocol that combines this method with normal (non-resonance) Raman microscopy to enable us to define molecular details of intermediates at early time points. With this combined method, SHV-1, a class A β-lactamase, and tazobactam, a commercially available β-lactamase inhibitor, were rapidly mixed on the millisecond time scale and then were flash-frozen by injection into an isopentane solution surrounded by liquid nitrogen. The "ice" was finally freeze-dried and characterized by Raman microscopy. We found that the reaction is almost complete in solution at 25 ms, giving rise to a major population composed of the trans-enamine intermediate. Between 25 and 500 ms, minor populations of protonated imine are detected that have previously been postulated to precede enamine intermediates. However, within 1 s, the imines are converted entirely to enamines. Interestingly, with this method, we can measure directly the turnover number of SHV-1 and tazobactam. The enzyme is completely inhibited at 1:4 ratio (enzyme:inhibitor) or greater, a number that agrees with the turnover number derived from steady-state kinetic methods. This application, employing non-intensity-enhanced Raman spectroscopy, provides a general and effective route to study the early events in enzyme-substrate reactions.
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22
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Sun S, Zhang W, Mannervik B, Andersson DI. Evolution of broad spectrum β-lactam resistance in an engineered metallo-β-lactamase. J Biol Chem 2013; 288:2314-24. [PMID: 23209299 PMCID: PMC3554903 DOI: 10.1074/jbc.m112.430199] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 11/28/2012] [Indexed: 11/06/2022] Open
Abstract
The extensive use and misuse of antibiotics during the last seven decades has led to the evolution and global spread of a variety of resistance mechanisms in bacteria. Of high medical importance are β-lactamases, a group of enzymes inactivating β-lactam antibiotics. Metallo-β-lactamases (MBLs) are particularly problematic because of their ability to act on virtually all classes of β-lactam antibiotics. An engineered MBL (evMBL9) characterized by low level activity with several β-lactam antibiotics was constructed and employed as a parental MBL in an experiment to examine how an enzyme can evolve toward increased activity with a variety of β-lactam antibiotics. We designed and synthesized a mutant library in which the substrate activity profile was varied by randomizing six active site amino acid residues. The library was expressed in Salmonella typhimurium, clones with increased resistance against seven different β-lactam antibiotics (penicillin G, ampicillin, cephalothin, cefaclor, cefuroxime, cefoperazone, and cefotaxime) were isolated, and the MBL variants were characterized. For the majority of the mutants, bacterial resistance was significantly increased despite marked reductions in both mRNA and protein levels relative to those of parental evMBL9, indicating that the catalytic activities of these mutant MBLs were highly increased. Multivariate analysis showed that the majority of the mutant enzymes were generalists, conferring increased resistance against most of the examined β-lactams.
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Affiliation(s)
- Song Sun
- From the Department of Medical Biochemistry and Microbiology, Uppsala University, SE-75123 Uppsala, Sweden
| | - Wei Zhang
- the Department of Chemistry-BMC, Uppsala University, SE-75123 Uppsala, Sweden, and
| | - Bengt Mannervik
- the Department of Chemistry-BMC, Uppsala University, SE-75123 Uppsala, Sweden, and
- the Department of Neurochemistry, Stockholm University SE-10961 Stockholm, Sweden
| | - Dan I. Andersson
- From the Department of Medical Biochemistry and Microbiology, Uppsala University, SE-75123 Uppsala, Sweden
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23
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Abstract
Pseudomonas aeruginosa is intrinsically resistant to a variety of antimicrobials and can develop resistance during anti-pseudomonal chemotherapy both of which compromise treatment of infections caused by this organism. Resistance to multiple classes of antimicrobials (multidrug resistance) in particular is increasingly common in P. aeruginosa, with a number of reports of pan-resistant isolates treatable with a single agent, colistin. Acquired resistance in this organism is multifactorial and attributable to chromosomal mutations and the acquisition of resistance genes via horizontal gene transfer. Mutational changes impacting resistance include upregulation of multidrug efflux systems to promote antimicrobial expulsion, derepression of ampC, AmpC alterations that expand the enzyme's substrate specificity (i.e., extended-spectrum AmpC), alterations to outer membrane permeability to limit antimicrobial entry and alterations to antimicrobial targets. Acquired mechanisms contributing to resistance in P. aeruginosa include β-lactamases, notably the extended-spectrum β-lactamases and the carbapenemases that hydrolyze most β-lactams, aminoglycoside-modifying enzymes, and 16S rRNA methylases that provide high-level pan-aminoglycoside resistance. The organism's propensity to grow in vivo as antimicrobial-tolerant biofilms and the occurrence of hypermutator strains that yield antimicrobial resistant mutants at higher frequency also compromise anti-pseudomonal chemotherapy. With limited therapeutic options and increasing resistance will the untreatable P. aeruginosa infection soon be upon us?
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Affiliation(s)
- Keith Poole
- Department of Microbiology and Immunology, Queen's University Kingston, ON, Canada
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24
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Poole K. Pseudomonas aeruginosa: resistance to the max. Front Microbiol 2011; 2:65. [PMID: 21747788 PMCID: PMC3128976 DOI: 10.3389/fmicb.2011.00065] [Citation(s) in RCA: 554] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 03/24/2011] [Indexed: 01/04/2023] Open
Abstract
Pseudomonas aeruginosa is intrinsically resistant to a variety of antimicrobials and can develop resistance during anti-pseudomonal chemotherapy both of which compromise treatment of infections caused by this organism. Resistance to multiple classes of antimicrobials (multidrug resistance) in particular is increasingly common in P. aeruginosa, with a number of reports of pan-resistant isolates treatable with a single agent, colistin. Acquired resistance in this organism is multifactorial and attributable to chromosomal mutations and the acquisition of resistance genes via horizontal gene transfer. Mutational changes impacting resistance include upregulation of multidrug efflux systems to promote antimicrobial expulsion, derepression of ampC, AmpC alterations that expand the enzyme's substrate specificity (i.e., extended-spectrum AmpC), alterations to outer membrane permeability to limit antimicrobial entry and alterations to antimicrobial targets. Acquired mechanisms contributing to resistance in P. aeruginosa include β-lactamases, notably the extended-spectrum β-lactamases and the carbapenemases that hydrolyze most β-lactams, aminoglycoside-modifying enzymes, and 16S rRNA methylases that provide high-level pan-aminoglycoside resistance. The organism's propensity to grow in vivo as antimicrobial-tolerant biofilms and the occurrence of hypermutator strains that yield antimicrobial resistant mutants at higher frequency also compromise anti-pseudomonal chemotherapy. With limited therapeutic options and increasing resistance will the untreatable P. aeruginosa infection soon be upon us?
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Affiliation(s)
- Keith Poole
- Department of Microbiology and Immunology, Queen's University Kingston, ON, Canada
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25
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Roles of residues Cys69, Asn104, Phe160, Gly232, Ser237, and Asp240 in extended-spectrum beta-lactamase Toho-1. Antimicrob Agents Chemother 2010; 55:284-90. [PMID: 21078949 DOI: 10.1128/aac.00098-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Toho-1, which is also designated CTX-M-44, is an extended-spectrum class A β-lactamase that has high activity toward cefotaxime. In this study, we investigated the roles of residues suggested to be critical for the substrate specificity expansion of Toho-1 in previous structural analyses. Six amino acid residues were replaced one by one with amino acids that are often observed in the corresponding position of non-extended-spectrum β-lactamases. The mutants produced in Escherichia coli strains were analyzed both for their kinetic properties and their effect on drug susceptibilities. The results indicate that the substitutions of Asn104 and Ser237 have certain effects on expansion of substrate specificity, while those of Cys69 and Phe160 have less effect, and that of Asp240 has no effect on the hydrolysis of any substrates tested. Gly232, which had been assumed to increase the flexibility of the substrate binding site, was revealed not to be critical for the expansion of substrate specificity of this enzyme, although this substitution resulted in deleterious effects on expression and stability of the enzyme.
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26
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Tremblay LW, Xu H, Blanchard JS. Structures of the Michaelis complex (1.2 Å) and the covalent acyl intermediate (2.0 Å) of cefamandole bound in the active sites of the Mycobacterium tuberculosis β-lactamase K73A and E166A mutants. Biochemistry 2010; 49:9685-7. [PMID: 20961112 DOI: 10.1021/bi1015088] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The genome of Mycobacterium tuberculosis (TB) contains a gene that encodes a highly active β-lactamase, BlaC, that imparts TB with resistance to β-lactam chemotherapy. The structure of covalent BlaC-β-lactam complexes suggests that active site residues K73 and E166 are essential for acylation and deacylation, respectively. We have prepared the K73A and E166A mutant forms of BlaC and have determined the structures of the Michaelis complex of cefamandole and the covalently bound acyl intermediate of cefamandole at resolutions of 1.2 and 2.0 Å, respectively. These structures provide insight into the details of the catalytic mechanism.
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Affiliation(s)
- Lee W Tremblay
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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27
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Abstract
OXA beta-lactamases are largely responsible for beta-lactam resistance in Acinetobacter spp. and Pseudomonas aeruginosa, two of the most difficult-to-treat nosocomial pathogens. In general, the beta-lactamase inhibitors used in clinical practice (clavulanic acid, sulbactam, and tazobactam) demonstrate poor activity against class D beta-lactamases. To overcome this challenge, we explored the abilities of beta-lactamase inhibitors of the C-2- and C-3-substituted penicillin and cephalosporin sulfone families against OXA-1, extended-spectrum (OXA-10, OXA-14, and OXA-17), and carbapenemase-type (OXA-24/40) class D beta-lactamases. Three C-2-substituted penicillin sulfone compounds (JDB/LN-1-255, JDB/LN-III-26, and JDB/ASR-II-292) showed low K(i) values for the OXA-1 beta-lactamase (0.70 +/- 0.14 --> 1.60 +/- 0.30 microM) and demonstrated significant K(i) improvements compared to the C-3-substituted cephalosporin sulfone (JDB/DVR-II-214), tazobactam, and clavulanic acid. The C-2-substituted penicillin sulfones JDB/ASR-II-292 and JDB/LN-1-255 also demonstrated low K(i)s for the OXA-10, -14, -17, and -24/40 beta-lactamases (0.20 +/- 0.04 --> 17 +/- 4 microM). Furthermore, JDB/LN-1-255 displayed stoichiometric inactivation of OXA-1 (the turnover number, i.e., the partitioning of the initial enzyme inhibitor complex between hydrolysis and enzyme inactivation [t(n)] = 0) and t(n)s ranging from 5 to 8 for the other OXA enzymes. Using mass spectroscopy to study the intermediates in the inactivation pathway, we determined that JDB/LN-1-255 inhibited OXA beta-lactamases by forming covalent adducts that do not fragment. On the basis of the substrate and inhibitor kinetics of OXA-1, we constructed a model showing that the C-3 carboxylate of JDB/LN-1-255 interacts with Ser115 and Thr213, the R-2 group at C-2 fits between the space created by the long B9 and B10 beta strands, and stabilizing hydrophobic interactions are formed between the pyridyl ring of JDB/LN-1-255 and Val116 and Leu161. By exploiting conserved structural and mechanistic features, JDB/LN-1-255 is a promising lead compound in the quest for effective inhibitors of OXA-type beta-lactamases.
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28
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Chen LF, Chopra T, Kaye KS. Pathogens Resistant to Antibacterial Agents. Infect Dis Clin North Am 2009; 23:817-45, vii. [DOI: 10.1016/j.idc.2009.06.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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29
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Drawz SM, Bethel CR, Hujer KM, Hurless KN, Distler AM, Caselli E, Prati F, Bonomo RA. The role of a second-shell residue in modifying substrate and inhibitor interactions in the SHV beta-lactamase: a study of ambler position Asn276. Biochemistry 2009; 48:4557-66. [PMID: 19351161 DOI: 10.1021/bi9003292] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inhibitor-resistant class A beta-lactamases of the TEM and SHV families that arise by single amino acid substitutions are a significant threat to the efficacy of beta-lactam/beta-lactamase inhibitor combinations. To better understand the basis of the inhibitor-resistant phenotype in SHV, we performed mutagenesis to examine the role of a second-shell residue, Asn276. Of the 19 variants expressed in Escherichia coli, only the Asn276Asp enzyme demonstrated reduced susceptibility to ampicillin/clavulanate (MIC increased from 50/2 --> 50/8 microg/mL) while maintaining high-level resistance to ampicillin (MIC = 8192 microg/mL). Steady-state kinetic analyses of Asn276Asp revealed slightly diminished k(cat)/K(m) for all substrates tested. In contrast, we observed a 5-fold increase in K(i) for clavulanate (7.4 +/- 0.9 microM for Asn276Asp vs 1.4 +/- 0.2 microM for SHV-1) and a 40% reduction in k(inact)/K(I) (0.013 +/- 0.002 microM(-1 )s(-1) for Asn276Asp vs 0.021 +/- 0.004 microM(-1) s(-1) for SHV-1). Timed electrospray ionization mass spectrometry of clavulanate-inhibited SHV-1 and SHV Asn276Asp showed nearly identical mass adducts, arguing for a similar pathway of inactivation. Molecular modeling shows that novel electrostatic interactions are formed between Arg244Neta2 and both 276AspOdelta1 and Odelta2; these new forces restrict the spatial position of Arg244, a residue important in the recognition of the C(3)/C(4) carboxylate of beta-lactam substrates and inhibitors. Testing the functional consequences of this interaction, we noted considerable free energy costs (+DeltaDeltaG) for substrates and inhibitors. A rigid carbapenem (meropenem) was most affected by the Asn276Asp substitution (46-fold increase in K(i) vs SHV-1). We conclude that residue 276 is an important second-shell residue in class A beta-lactamase-mediated resistance to substrates and inhibitors, and only Asn is able to precisely modulate the conformational flexibility of Arg244 required for successful evolution in nature.
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Affiliation(s)
- Sarah M Drawz
- Department of Pathology, CaseWestern Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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Kalp M, Totir MA, Buynak JD, Carey PR. Different intermediate populations formed by tazobactam, sulbactam, and clavulanate reacting with SHV-1 beta-lactamases: Raman crystallographic evidence. J Am Chem Soc 2009; 131:2338-47. [PMID: 19161282 DOI: 10.1021/ja808311s] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tazobactam, sulbactam, and clavulanic acid are the only beta-lactamase inhibitors in clinical use. Comparative inhibitory activities of clavulanic acid, sulbactam, and tazobactam against clinically important beta-lactamases conclude that tazobactam is superior to both clavulanic acid and sulbactam. Thus far, the majority of explanations for this phenomenon have relied on kinetic studies, which report differences in the ligands' apparent dissociation constants and number of turnovers before inactivation. Due their innate limitations, these investigations do not examine the identity of intermediates on the reaction pathway and relate them to the efficacy of the inhibitors. In the present study, the reactions between the three inhibitors and SHV-1 beta-lactamase have been examined in single crystals using a Raman microscope. The results show that tazobactam forms a predominant population of trans-enamine, a chemically inert species, with SHV-1, while clavulanate and sulbactam form a mixture of trans-enamine and two labile species, the cis-enamine and imine. The same reactions are then reexamined using a deacylation-deficient variant, SHV E166A, that has been used to trap acyl-enzyme intermediates for X-ray crystallographic analysis. Our Raman data show that significant differences exist between the wild-type and SHV E166A acyl-enzyme populations. Namely, compared to SHV-1, sulbactam shows significantly smaller populations of cis-enamine and imine in the E166A variant, while clavulanate exists almost exclusively as trans-enamine in the E166A active site. Using clavulanate as an example, we also show that Raman crystallography can provide novel information on the presence of multiple conformers or tautomers for intermediates within a complex reaction pathway. These insights caution against the interpretation of experimental data obtained with deacylation-deficient beta-lactamases to make mechanistic conclusions about inhibitors within the enzyme.
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Affiliation(s)
- Matthew Kalp
- Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA
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Pyrosequencing using the single-nucleotide polymorphism protocol for rapid determination of TEM- and SHV-type extended-spectrum beta-lactamases in clinical isolates and identification of the novel beta-lactamase genes blaSHV-48, blaSHV-105, and blaTEM-155. Antimicrob Agents Chemother 2008; 53:977-86. [PMID: 19075050 DOI: 10.1128/aac.01155-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
TEM- and SHV-type extended-spectrum beta-lactamases (ESBLs) are the most common ESBLs found in the United States and are prevalent throughout the world. Amino acid substitutions at a number of positions in TEM-1 lead to the ESBL phenotype, although substitutions at residues 104 (E to K), 164 (R to S or H), 238 (G to S), and 240 (E to K) appear to be particularly important in modifying the spectrum of activity of the enzyme. The SHV-1-derived ESBLs are a less diverse collection of enzymes; however, the majority of amino acid substitutions resulting in an ESBL mirror those seen in the TEM-1-derived enzymes. Pyrosequencing by use of the single-nucleotide polymorphism (SNP) protocol was applied to provide sequence data at positions critical for the ESBL phenotype spanning the bla(TEM) and bla(SHV) genes. Three novel beta-lactamases are described: the ESBLs TEM-155 (Q39K, R164S, E240K) and SHV-105 (I8F, R43S, G156D, G238S, E240K) and a non-ESBL, SHV-48 (V119I). The ceftazidime, ceftriaxone, and aztreonam MICs for an Escherichia coli isolate expressing bla(SHV-105) were >128, 128, and >128 microg/ml, respectively. Likewise, the ceftazidime, ceftriaxone, and aztreonam MICs for an E. coli isolate expressing bla(TEM-155) were >128, 64, and > 128 microg/ml, respectively. Pyrosequence analysis determined the true identity of the beta-lactamase on plasmid R1010 to be SHV-11 rather than SHV-1, as previously reported. Pyrosequencing is a real-time sequencing-by-synthesis approach that was applied to SNP detection for TEM- and SHV-type ESBL identification and represents a robust tool for rapid sequence determination that may have a place in the clinical setting.
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Characterization and sequence analysis of extended-spectrum-{beta}-lactamase-encoding genes from Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis isolates collected during tigecycline phase 3 clinical trials. Antimicrob Agents Chemother 2008; 53:465-75. [PMID: 19015360 DOI: 10.1128/aac.00883-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In concert with the development of novel beta-lactams and broad-spectrum cephalosporins, bacterially encoded beta-lactamases have evolved to accommodate the new agents. This study was designed to identify, at the sequence level, the genes responsible for the extended-spectrum-beta-lactamase (ESBL) phenotypes of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis isolates collected during the global tigecycline phase 3 clinical trials. PCR assays were developed to identify and clone the bla(TEM), bla(SHV), bla(OXA), and bla(CTX) genes from clinical strains. Isolates were also screened for AmpC genes of the bla(CMY), bla(ACT), bla(FOX), and bla(DHA) families as well as the bla(KPC) genes encoding class A carbapenemases. E. coli, K. pneumoniae, and P. mirabilis isolates with ceftazidime MICs of > or =2 microg/ml were designated possible ESBL-producing pathogens and were then subjected to a confirmatory test for ESBLs by use of Etest. Of 272 unique patient isolates, 239 were confirmed by PCR and sequencing to carry the genes for at least one ESBL, with 44% of the positive isolates harboring the genes for multiple ESBLs. In agreement with current trends for ESBL distribution, bla(CTX-M)-type beta-lactamase genes were found in 83% and 71% of the ESBL-positive E. coli and K. pneumoniae isolates, respectively, whereas bla(SHV) genes were found in 41% and 28% of the ESBL-positive K. pneumoniae and E. coli isolates, respectively. Ninety-seven percent of the E. coli and K. pneumoniae isolates were tigecycline susceptible (MIC(90) = 2 microg/ml), warranting further studies to define the therapeutic utility of tigecycline against strains producing ESBLs in a clinical setting.
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Shah AA, Hasan F, Ahmed S, Hameed A. Extended-Spectrum β-Lactamases (ESBLs): Characterization, Epidemiology and Detection. Crit Rev Microbiol 2008; 30:25-32. [PMID: 15116761 DOI: 10.1080/10408410490266429] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Beta-lactamases of Enterobacteriaceae are the most important mechanism of resistance against beta-lactam drugs. Two types of beta-lactamases can confer resistance against 3rd generation cephalosporins. Chromosomally mediated beta-lactamases are inducible and are not inhibited by clavulanic acid. Resistance due to these enzymes is non-transferable. The 2nd type of enzyme is plasmid-mediated beta-lactamases, which are inhibited by clavulanic acid. These enzymes are more important clinically as these can be transferred between various species of Enterobacteriaceae. These enzymes are called extended-spectrum beta-lactamases (ESBLs). ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infection throughout the world and pose challenging infection control issues. Antibacterial choice is often complicated by multi-resistance. ESBLs can confer resistance against all beta-lactam drugs except carbapenems and cephamycins. Nursing home patients may be an important reservoir of ESBL-containing multiple antibiotic-resistant organisms. Use of broad-spectrum oral antibiotics and probably poor infection control practices may facilitate spread of this plasmid-mediated resistance. In addition to known populations at risk, ambulatory patients with chronic conditions represent another patient population that may harbor ESBL-producing organisms. Various methods can be used for detection of ESBLs in the laboratory. These tests include double disc diffusion test, Vitek ESBL test, E Tests, MIC Determination, genetic method, and isoelectric focusing (IEF).
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Affiliation(s)
- A A Shah
- Microbiology Research Laboratory, Department of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
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Nukaga M, Bethel CR, Thomson JM, Hujer AM, Distler A, Anderson VE, Knox JR, Bonomo RA. Inhibition of class A beta-lactamases by carbapenems: crystallographic observation of two conformations of meropenem in SHV-1. J Am Chem Soc 2008; 130:12656-62. [PMID: 18761444 DOI: 10.1021/ja7111146] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbapenem antibiotics are often the "last resort" in the treatment of infections caused by bacteria resistant to penicillins and cephalosporins. To understand why meropenem is resistant to hydrolysis by the SHV-1 class A beta-lactamase, the atomic structure of meropenem inactivated SHV-1 was solved to 1.05 A resolution. Two conformations of the Ser70 acylated intermediate are observed in the SHV-1-meropenem complex; the meropenem carbonyl oxygen atom of the acyl-enzyme is in the oxyanion hole in one conformation, while in the other conformation it is not. Although the structures of the SHV-1 apoenzyme and the SHV-1-meropenem complex are very similar (0.29 A rmsd for Calpha atoms), the orientation of the conserved Ser130 is different. Notably, the Ser130-OH group of the SHV-1-meropenem complex is directed toward Lys234Nz, while the Ser130-OH of the apo enzyme is oriented toward the Lys73 amino group. This altered position may affect proton transfer via Ser130 and the rate of hydrolysis. A most intriguing finding is the crystallographic detection of protonation of the Glu166 known to be involved in the deacylation mechanism. The critical deacylation water molecule has an additional hydrogen-bonding interaction with the OH group of meropenem's 6alpha-1 R-hydroxyethyl substituent. This interaction may weaken the nucleophilicity and/or change the direction of the lone pair of electrons of the water molecule and result in poor turnover of meropenem by the SHV-1 beta-lactamase. Using timed mass spectrometry, we further show that meropenem is covalently attached to SHV-1 beta-lactamase for at least 60 min. These observations explain key properties of meropenem's ability to resist hydrolysis by SHV-1 and lead to important insights regarding future carbapenem and beta-lactamase inhibitor design.
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Affiliation(s)
- Michiyosi Nukaga
- Faculty of Pharmaceutical Sciences, Josai International University, Togane City, Chiba 283-8555, Japan
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Abriata LA, González LJ, Llarrull LI, Tomatis PE, Myers WK, Costello AL, Tierney DL, Vila AJ. Engineered mononuclear variants in Bacillus cereus metallo-beta-lactamase BcII are inactive. Biochemistry 2008; 47:8590-9. [PMID: 18652482 PMCID: PMC2565585 DOI: 10.1021/bi8006912] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metallo-beta-lactamases (MbetaLs) are zinc enzymes able to hydrolyze almost all beta-lactam antibiotics, rendering them inactive, at the same time endowing bacteria high levels of resistance. The design of inhibitors active against all classes of MbetaLs has been hampered by their structural diversity and by the heterogeneity in metal content in enzymes from different sources. BcII is the metallo-beta-lactamase from Bacillus cereus, which is found in both the mononuclear and dinuclear forms. Despite extensive studies, there is still controversy about the nature of the active BcII species. Here we have designed two mutant enzymes in which each one of the metal binding sites was selectively removed. Both mutants were almost inactive, despite preserving most of the structural features of each metal site. These results reveal that neither site isolated in the MbetaL scaffold is sufficient to render a fully active enzyme. This suggests that only the dinuclear species is active or that the mononuclear variants can be active only if aided by other residues that would be metal ligands in the dinuclear species.
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Affiliation(s)
| | | | | | | | | | | | | | - Alejandro J. Vila
- To whom correspondence should be addressed. Phone: +54−341−4350661, ext. 108. Fax: +54−341−4390465. E-mail:
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Mansour TS, Agarwal A, Venkatesan A, Abe T, Mihira A, Takasaki T, Sato K, Ushirogochi H, Yamamura I, Isoda T, Li Z, Yang Y, Kumagai T. On the absolute configuration in 1,4-dihydrothiazepine covalent complexes derived from inhibition of class A and C beta-lactamases with 6-methylidene penems. ChemMedChem 2008; 2:1713-6. [PMID: 17868160 DOI: 10.1002/cmdc.200700144] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Tarek S Mansour
- Chemical and Screening Sciences and Infectious Diseases Wyeth Research, 401 North Middeltown Road, Pearl River, NY 10965, USA.
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Metallo-beta-lactamases of Pseudomonas aeruginosa--a novel mechanism resistance to beta-lactam antibiotics. Folia Histochem Cytobiol 2008; 46:137-42. [PMID: 18519228 DOI: 10.2478/v10042-008-0020-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Since about twenty years, following the introduction into therapeutic of news beta-lactam antibiotics (broad-spectrum cephalosporins, monobactams and carbapenems), a very significant number of new beta-lactamases appeared. These enzymes confer to the bacteria which put them, the means of resisting new molecules. The genetic events involved in this evolution are of two types: evolution of old enzymes by mutation and especially appearance of new genes coming for some, from bacteria of the environment. Numerous mechanisms of enzymatic resistance to the carbapenems have been described in Pseudomonas aeruginosa. The important mechanism of inactivation carbapenems is production variety of b-lactam hydrolysing enzymes associated to carbapenemases. The metallo-beta-enzymes (IMP, VIM, SPM, GIM types) are the most clinically significant carbapenemases. P. aeruginosa posses MBLs and seem to have acquired them through transmissible genetic elements (plasmids or transposons associated with integron) and can be transmission to other bacteria. They have reported worldwide but mostly from South East Asia and Europe. The enzymes, belonging to the molecular class B family, are the most worrisome of all beta-lactamases because they confer resistance to carbapenems and all the beta-lactams (with the exception of aztreonam) and usually to aminoglycosides and quinolones. The dissemination of MBLs genes is thought to be driven by regional consumption of extended--spectrum antibiotics (e.g. cephalosporins and carbapenems), and therefore care must be taken that these drugs are not used unnecessarily.
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Abstract
The partnering of a beta-lactam with a beta-lactamase inhibitor is a highly effective strategy that can be used to combat bacterial resistance to beta-lactam antibiotics mediated by serine beta-lactamases (EC 3.2.5.6). To this end, we tested two novel penem inhibitors against OXA-1, a class D beta-lactamase that is resistant to inactivation by tazobactam. The K(i) of each penem inhibitor for OXA-1 was in the nM range (K(i) of penem 1, 45 +/- 8 nM; K(i) of penem 2, 12 +/- 2 nM). The first-order rate constant for enzyme and inhibitor complex inactivation of penems 1 and 2 for OXA-1 beta-lactamase were 0.13 +/- 0.01 s(-1) and 0.11 +/- 0.01 s(-1), respectively. By using an inhibitor-to-enzyme ratio of 1:1, 100% inactivation was achieved in <or=900 s and the recovery of OXA-1 beta-lactamase activity was not detected at 24 h. Covalent adducts of penems 1 and 2 (changes in molecular masses, +306 +/- 3 and +321 +/- 3 Da, respectively) were identified by electrospray ionization mass spectrometry (ESI-MS). After tryptic digestion of OXA-1 inactivated by penems 1 and 2, ESI-MS and matrix-assisted laser desorption ionization-time-of-flight MS identified the adducts of 306 +/- 3 and 321 +/- 3 Da attached to the peptide containing the active-site Ser67. The base hydrolysis of penem 2, monitored by serial (1)H nuclear magnetic resonance analysis, suggested that penem 2 formed a linear imine species that underwent 7-endo-trig cyclization to ultimately form a cyclic enamine, the 1,4-thiazepine derivative. Susceptibility testing demonstrated that the penem inhibitors at 4 mg/liter effectively restored susceptibility to piperacillin. Penem beta-lactamase inhibitors which demonstrate high affinities and which form long-lived acyl intermediates may prove to be extremely useful against the broad range of inhibitor-resistant serine beta-lactamases present in gram-negative bacteria.
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Hugonnet JE, Blanchard JS. Irreversible inhibition of the Mycobacterium tuberculosis beta-lactamase by clavulanate. Biochemistry 2007; 46:11998-2004. [PMID: 17915954 DOI: 10.1021/bi701506h] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Members of the beta-lactam class of antibiotics, which inhibit the bacterial d,d-transpeptidases involved in cell wall biosynthesis, have never been used systematically in the treatment of Mycobacterium tuberculosis infections because of this organism's resistance to beta-lactams. The critical resistance factor is the constitutive production of a chromosomally encoded, Ambler class A beta-lactamase, BlaC in M. tuberculosis. We show that BlaC is an extended spectrum beta-lactamase (ESBL) with high levels of penicillinase and cephalosporinase activity as well as measurable activity with carbapenems, including imipenem and meropenem. We have characterized the enzyme's inhibition by three FDA-approved beta-lactamase inhibitors: sulbactam, tazobactam, and clavulanate. Sulbactam inhibits the enzyme competitively and reversibly with respect to nitrocefin. Tazobactam inhibits the enzyme in a time-dependent manner, but the activity of the enzyme reappears due to the slow hydrolysis of the covalently acylated enzyme. In contrast, clavulanate reacts with the enzyme quickly to form hydrolytically stable, inactive forms of the enzyme that have been characterized by mass spectrometry. Clavulanate has potential to be used in combination with approved beta-lactam antibiotics to treat multi-drug resistant (MDR) and extremely drug resistant (XDR) strains of M. tuberculosis.
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Affiliation(s)
- Jean-Emmanuel Hugonnet
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Padayatti PS, Sheri A, Totir MA, Helfand MS, Carey MP, Anderson VA, Carey PR, Bethel CR, Bonomo RA, Buynak JD, van den Akker F. Rational design of a beta-lactamase inhibitor achieved via stabilization of the trans-enamine intermediate: 1.28 A crystal structure of wt SHV-1 complex with a penam sulfone. J Am Chem Soc 2007; 128:13235-42. [PMID: 17017804 PMCID: PMC2593906 DOI: 10.1021/ja063715w] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
beta-Lactamases are one of the major causes of antibiotic resistance in Gram negative bacteria. The continuing evolution of beta-lactamases that are capable of hydrolyzing our most potent beta-lactams presents a vexing clinical problem, in particular since a number of them are resistant to inhibitors. The efficient inhibition of these enzymes is therefore of great clinical importance. Building upon our previous structural studies that examined tazobactam trapped as a trans-enamine intermediate in a deacylation deficient SHV variant, we designed a novel penam sulfone derivative that forms a more stable trans-enamine intermediate. We report here the 1.28 A resolution crystal structure of wt SHV-1 in complex with a rationally designed penam sulfone, SA2-13. The compound is covalently bound to the active site of wt SHV-1 similar to tazobactam yet forms an additional salt-bridge with K234 and hydrogen bonds with S130 and T235 to stabilize the trans-enamine intermediate. Kinetic measurements show that SA2-13, once reacted with SHV-1 beta-lactamase, is about 10-fold slower at being released from the enzyme compared to tazobactam. Stabilizing the trans-enamine intermediate represents a novel strategy for the rational design of mechanism-based class A beta-lactamase inhibitors.
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Affiliation(s)
- Pius S. Padayatti
- Department of Biochemistry, Case Western Reserve University, Cleveland Ohio 44106
| | - Anjaneyulu Sheri
- Department of Chemistry, Southern Methodist University, Dallas TX 75275-0314
| | - Monica A. Totir
- Department of Chemistry, Case Western Reserve University, Cleveland Ohio 44106
| | - Marion S. Helfand
- Research Division, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland Ohio 44106
| | - Marianne P. Carey
- Department of Biochemistry, Case Western Reserve University, Cleveland Ohio 44106
| | - Vernon A. Anderson
- Department of Biochemistry, Case Western Reserve University, Cleveland Ohio 44106
| | - Paul R. Carey
- Department of Biochemistry, Case Western Reserve University, Cleveland Ohio 44106
| | - Christopher R. Bethel
- Research Division, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland Ohio 44106
| | - Robert A. Bonomo
- Research Division, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland Ohio 44106
- Department of Pharmacology, Case Western Reserve University, Cleveland Ohio 44106
| | - John D. Buynak
- Department of Chemistry, Southern Methodist University, Dallas TX 75275-0314
| | - Focco van den Akker
- Department of Biochemistry, Case Western Reserve University, Cleveland Ohio 44106
- Corresponding author:
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Totir MA, Helfand MS, Carey MP, Sheri A, Buynak JD, Bonomo RA, Carey PR. Sulbactam forms only minimal amounts of irreversible acrylate-enzyme with SHV-1 beta-lactamase. Biochemistry 2007; 46:8980-7. [PMID: 17630699 PMCID: PMC2596720 DOI: 10.1021/bi7006146] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sulbactam is a mechanism-based inhibitor of beta-lactamase enzymes used in clinical practice. It undergoes a complex series of chemical reactions in the active site that have been studied extensively in the past three decades. However, the actual species that gives rise to inhibition in a clinical setting has not been established. Recent studies by our group, using Raman microscopy and X-ray crystallography, have found that large quantities of enamine-based acyl-enzyme species are present within minutes in single crystals of SHV-1 beta-lactamases which can lead to significant inhibition. The enamines are formed by breakdown of the cyclic beta-lactam structures with further transformations leading to imine formation and subsequent isomerization to cis and/or trans enamines. Another favored form of inhibition arises from attack on the imine by a second nucleophilic amino acid side chain, e.g., from serine 130, to form a cross-linked species in the active site that can degrade to an acrylate-like species irreversibly bound to the enzyme. Thus, the imine is at a branch point on the reaction pathway. Using sulbactam and 6,6-dideuterated sulbactam we follow these alternate paths in WT and E166A SHV-1 beta-lactamase by means of Raman microscopic studies on single enzyme crystals. For the unlabeled sulbactam, the Raman data show the presence of an acrylate-like species, probably 3-serine acrylate, several hours after the reaction is started in the crystal. However, for the 6,6-dideutero analogue the acrylate signature appears on the time scale of minutes. The Raman signatures, principally an intense feature near 1530 cm-1, are assigned based on quantum mechanical calculations on model compounds that mimic acrylate species in the active site. The different time scales observed for acrylate-like product formation are ascribed to different rates of reaction involving the imine intermediate. It is proposed that for the unsubstituted sulbactam the conversion from imine to enamine, which involves breaking a C-H bond, is aided by quantum mechanical tunneling. For the 6,6-dideutero-sulbactam the same step involves breaking a C-D bond, which has little or no assistance from tunneling. Consequently the conversion to enamines is slower, and a higher population of imine results, presenting the opportunity for the competing reaction with the second nucleophile, serine 130 being the prime candidate. The hydrolysis of the resulting cross-linked intermediate leads to the observed rapid buildup of the acrylate product in the Raman spectra from the dideutero analogue. The protocol used here, essentially running the reactions with the two forms of sulbactam in parallel, provides an element of control and enables us to conclude that, for the unsubstituted sulbactam, the formation of the cross-linked intermediate and the final irreversible acrylate product is not a significant route to inhibition of SHV-1.
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Affiliation(s)
- Monica A. Totir
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Marion S. Helfand
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
- Research Division, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106
| | - Marianne P. Carey
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Anjaneyulu Sheri
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75205
| | - John D. Buynak
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75205
| | - Robert A. Bonomo
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
- Research Division, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106
| | - Paul R. Carey
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
- * To whom correspondence should be addressed: . Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue Cleveland, Ohio 44106 Tel. (216) 368 0031 Fax (216) 368 3419
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Schlüter A, Szczepanowski R, Pühler A, Top EM. Genomics of IncP-1 antibiotic resistance plasmids isolated from wastewater treatment plants provides evidence for a widely accessible drug resistance gene pool. FEMS Microbiol Rev 2007; 31:449-77. [PMID: 17553065 DOI: 10.1111/j.1574-6976.2007.00074.x] [Citation(s) in RCA: 286] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The dramatic spread of antibiotic resistance is a crisis in the treatment of infectious diseases that affect humans. Several studies suggest that wastewater treatment plants (WWTP) are reservoirs for diverse mobile antibiotic resistance elements. This review summarizes findings derived from genomic analysis of IncP-1 resistance plasmids isolated from WWTP bacteria. Plasmids that belong to the IncP-1 group are self-transmissible, and transfer to and replicate in a wide range of hosts. Their backbone functions are described with respect to their impact on vegetative replication, stable maintenance and inheritance, mobility and plasmid control. Accessory genetic modules, mainly representing mobile genetic elements, are integrated in-between functional plasmid backbone modules. These elements carry determinants conferring resistance to nearly all clinically relevant antimicrobial drug classes, to heavy metals, and quaternary ammonium compounds used as disinfectants. All plasmids analysed here contain integrons that potentially facilitate integration, exchange and dissemination of resistance gene cassettes. Comparative genomics of accessory modules located on plasmids from WWTP and corresponding modules previously identified in other bacterial genomes revealed that animal, human and plant pathogens and other bacteria isolated from different habitats share a common pool of resistance determinants.
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Affiliation(s)
- Andreas Schlüter
- Fakultät für Biologie, Lehrstuhl für Genetik, Universität Bielefeld, Bielefeld, Germany
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Helfand MS, Taracila MA, Totir MA, Bonomo RA, Buynak JD, van den Akker F, Carey PR. Raman crystallographic studies of the intermediates formed by Ser130Gly SHV, a beta-lactamase that confers resistance to clinical inhibitors. Biochemistry 2007; 46:8689-99. [PMID: 17595114 DOI: 10.1021/bi700581q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antibiotic resistance to beta-lactam compounds in Gram-negative bacteria such as Escherichia coli and Klebsiella pneumoniae is often mediated by beta-lactamase enzymes like TEM and SHV. Previously, a limited number of inhibitors have shown efficacy in combating such bacterial drug resistance. However, many Gram-negative pathogens have evolved inhibitor resistant forms of these hydrolytic enzymes. A single point mutation of the active site residue Ser130 to a Gly in either TEM or SHV results in resistance to amoxicillin and clavulanic acid, an important clinical beta-lactam-beta-lactamase inhibitor combination antibiotic. Previous structural and modeling studies of the S130G mutants of TEM and SHV have shown differences in how these two distinct but closely related enzymes compensate for the loss of the Ser130 residue. In the case of S130G SHV, a structure of tazobactam in the active site has suggested that the inhibitor preferentially assumes a cis-enamine intermediate form when the Ser130 hydroxyl is absent. Raman crystallographic studies of S130G SHV inhibited with tazobactam, sulbactam, clavulanic acid, and 2'-glutaroxy penem sulfone (SA2-13) were performed with the aim of identifying the type and amount of intermediate formed with each drug to understand the role of the S130G mutation in formation of the important enamine intermediates. It is demonstrated that with the exception of sulbactam, each compound forms observable trans-enamine intermediates. For S130G reacted with tazobactam, identical steady state levels of enamine are achieved when compared to those of wild-type (WT) or even deacylation deficient forms of the enzyme. With clavulanic acid, slightly smaller amounts of enamine are observed within the first 30 min of the reaction but are not significantly different than those for tazobactam. Thus, the resistance mutation does not substantially affect the amount of trans-enamine formed with clavulanic acid during the critical early time period of inhibition. This finding has important implications in the design of beta-lactamase inhibitors for drug resistant variants like S130G SHV.
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Affiliation(s)
- Marion S Helfand
- Research Service and Infectious Diseases Section, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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Totir MA, Padayatti PS, Helfand MS, Carey MP, Bonomo RA, Carey PR, van den Akker F. Effect of the inhibitor-resistant M69V substitution on the structures and populations of trans-enamine beta-lactamase intermediates. Biochemistry 2006; 45:11895-904. [PMID: 17002290 PMCID: PMC2596060 DOI: 10.1021/bi060990m] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The objective of this study was to determine the molecular factors that lead to beta-lactamase inhibitor resistance for the M69V variant in SHV-1 beta-lactamase. With mechanism-based inhibitors, the beta-lactamase forms an acyl-enzyme intermediate that consists of a trans-enamine derivative in the active site. This study focuses on these intermediates by introducing the E166A mutation that greatly retards deacylation. Thus, by comparing the properties of the E166A and M69V/E166A forms, we can explore the consequences of the resistance mutation at the level of the enamine acyl-enzyme forms. The reactions between the beta-lactamase and the inhibitors tazobactam, sulbactam, and clavulanic acid are followed in single crystals of the enzymes by using a Raman microscope. The resulting Raman difference spectroscopic data provide detailed information about conformational events involving the enamine species as well as an estimate of their populations. The Raman difference spectra for each of the inhibitors in the E166A and M69V/E166A variants are very similar. In particular, detailed analysis of the main enamine Raman vibration near 1595 cm(-1) reveals that the structure and flexibility of the enamine fragments are essentially identical for each of the three inhibitors in E166A and in the M69V/E166A double mutant. This finding is in accord with the X-ray-derived structures, presented herein at 1.6-1.75 A resolution, of the trans-enamine intermediates formed by the three inhibitors in M69V/E166A. However, a comparison of Raman results for M69V/E166A and E166A shows that the M69V mutation results in a 40%, 25%, and negligible reductions in the enamine population when the beta-lactamase crystals are soaked in 5 mM tazobactam, clavulanic acid, and sulbactam solutions, respectively. The levels of enamine from tazobactam and clavulanic acid can be increased by increasing the concentrations of inhibitor in the mother liquor. Thus, the sensitivity of population levels to the inhibitor concentration in the mother liquor focuses attention on the properties of the encounter complex preceding acylation. It is proposed that for small ligands, such as tazobactam, sulbactam, and clavulanic acid, the positioning of the lactam ring in the active site in the correct orientation for acylation is only one of a number of poorly defined conformations. For tazobactam and clavulanic acid, the correctly oriented encounter complex is even less likely in the M69V variant, leading to a reduction in the level of inhibition of the enzyme via formation of the acyl-enzyme intermediate and the onset of resistance. Analysis of the X-ray structures of the three intermediates in M69V/E166A demonstrates that, compared to the structures for the E166A form, the oxyanion hole becomes smaller, providing one explanation for why acylation may be less efficient following the M69V substitution.
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Affiliation(s)
- Monica A Totir
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Abstract
The most compelling reason for practicing judicious antimicrobial use is to facilitate therapeutic success. The definition of therapeutic success has changed in recent years, however; not only does success include eradication of infection, but it must now include avoidance of resistance. If the goal of antimicrobial therapy is to achieve sufficient concentrations at the site of infection such that the infecting organism is killed, therapy should be successful.
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Affiliation(s)
- Dawn Merton Boothe
- Department of Anatomy, Physiology, and Pharmacology, 109 Greene Hall, College of Veterinary Medicine, Auburn University, AL 36849, USA.
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Shimizu-Ibuka A, Matsuzawa H, Sakai H. Effect of disulfide-bond introduction on the activity and stability of the extended-spectrum class A β-lactamase Toho-1. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:1349-55. [PMID: 16890032 DOI: 10.1016/j.bbapap.2006.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2005] [Revised: 05/24/2006] [Accepted: 06/09/2006] [Indexed: 10/24/2022]
Abstract
The production of class A beta-lactamases is a major cause of clinical resistance to beta-lactam antibiotics. Some of class A beta-lactamases are known to have a disulfide bridge. Both narrow spectrum and extended spectrum beta-lactamases of TEM and the SHV enzymes possess a disulfide bond between Cys77 and Cys123, and the enzymes with carbapenem-hydrolyzing activity have a well-conserved disulfide bridge between Cys69 and Cys238. We produced A77C/G123C mutant of the extended-spectrum beta-lactamase Toho-1 in order to introduce a disulfide bond between the cysteine residues at positions 77 and 123. The result of 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) titrations confirmed formation of a new disulfide bridge in the mutant. The results of irreversible heat inactivation and circular dichroism (CD) melting experiments indicated that the disulfide bridge stabilized the enzyme significantly. Though kinetic analysis indicated that the catalytic properties of the mutant were quite similar to those of the wild-type enzyme, E. coli producing this mutant showed drug resistance significantly higher than E. coli producing the wild-type enzyme. We speculate that the stability of the enzymes provided by the disulfide bond may explain the wide distribution of TEM and SHV derivatives and explain how various mutations can cause broadened substrate specificity without loss of stability.
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Affiliation(s)
- Akiko Shimizu-Ibuka
- Department of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
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Mikolasch A, Niedermeyer THJ, Lalk M, Witt S, Seefeldt S, Hammer E, Schauer F, Gesell M, Hessel S, Jülich WD, Lindequist U. Novel penicillins synthesized by biotransformation using laccase from Trametes spec. Chem Pharm Bull (Tokyo) 2006; 54:632-8. [PMID: 16651757 DOI: 10.1248/cpb.54.632] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eight novel penicillins were synthesized by heteromolecular reaction of ampicillin or amoxicillin with 2,5-dihydroxybenzoic acid derivatives using a laccase from Trametes spec. All products inhibited the growth of several gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci. The products protected mice against an infection with Staphylococcus aureus lethal to the untreated animals. Cytotoxicity and acute toxicity of the new compounds were neglectable. The results show the usefulness of laccase for the synthesis of potential new antibiotics. The biological activity of the new compounds stimulates intensified pharmacological tests.
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Affiliation(s)
- Annett Mikolasch
- Institute of Microbiology, Ernst-Moritz-Arndt-University Greifswald, F.-L.-Jahn-Strasse 15, 17489 Greifswald, Germany.
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Abstract
Recent studies using a Raman microscope have shown that single protein crystals provide an ideal platform to undertake Raman difference spectroscopic analyses under nonresonance conditions. This approach, termed Raman crystallography, provides a means of characterizing chemical events within the crystal such as ligand binding and enzyme reactions. In many cases Raman crystallography goes hand in hand with X-ray crystallographic studies because the Raman results can inform the X-ray crystallographer about the status of chemical events in the crystal prior to flash freezing and X-ray analysis. In turn, the combined data from the Raman and X-ray analyses are highly synergistic and offer novel perspectives on structure and dynamics in enzyme active sites. In a related area, protein misfolding, Raman microscopy can provide detailed insights into the chemistry of the amyloid plaques associated with Alzheimer's disease and into the intermediates on the alpha-synuclein protein misfolding pathway implicated in Parkinson's disease.
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Affiliation(s)
- Paul R Carey
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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