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Thoden JB, Benin BM, Priebe A, Shin WS, Muthyala R, Sham YY, Holden HM. Characterization of a novel inhibitor for the New Delhi metallo-β-lactamase-4: Implications for drug design and combating bacterial drug resistance. J Biol Chem 2023; 299:105135. [PMID: 37549809 PMCID: PMC10514461 DOI: 10.1016/j.jbc.2023.105135] [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: 06/12/2023] [Revised: 07/18/2023] [Accepted: 08/01/2023] [Indexed: 08/09/2023] Open
Abstract
The bacterial metallo-β-lactamases (MBLs) catalyze the inactivation of β-lactam antibiotics. Identifying novel pharmacophores remains crucial for the clinical development of additional MBL inhibitors. Previously, 1-hydroxypyridine-2(1H)-thione-6-carboxylic acid, hereafter referred to as 1,2-HPT-6-COOH, was reported as a low cytotoxic nanomolar β-lactamase inhibitor of Verona-integron-encoded metallo-β-lactamase 2, capable of rescuing β-lactam antibiotic activity. In this study, we explore its exact mechanism of inhibition and the extent of its activity through structural characterization of its binding to New Delhi metallo-β-lactamase 4 (NDM-4) and its inhibitory activity against both NDM-1 and NDM-4. Of all the structure-validated MBL inhibitors available, 1,2-HPT-6-COOH is the first discovered compound capable of forming an octahedral coordination sphere with Zn2 of the binuclear metal center. This unexpected mechanism of action provides important insight for the further optimization of 1,2-HPT-6-COOH and the identification of additional pharmacophores for MBL inhibition.
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Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA
| | - Bogdan M Benin
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Adam Priebe
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Woo Shik Shin
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Ramaiah Muthyala
- Department of Experimental & Clinical Pharmacology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yuk Yin Sham
- Department of Experimental & Clinical Pharmacology, University of Minnesota, Minneapolis, Minnesota, USA; Bioinformatics and Computational Biology Program, University of Minnesota, Minneapolis, Minnesota, USA.
| | - Hazel M Holden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA.
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2
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Bovo F, Lombardo D, Lazzarotto T, Ambretti S, Gaibani P. Epidemiology and In Vitro Activity of Ceftazidime/Avibactam, Meropenem/Vaborbactam and Imipenem/Relebactam against KPC-Producing K. pneumoniae Collected from Bacteremic Patients, 2018 to 2020. Antibiotics (Basel) 2022; 11:antibiotics11111621. [PMID: 36421265 PMCID: PMC9686929 DOI: 10.3390/antibiotics11111621] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
The management of KPC-producing K. pneumoniae (KPC-Kp) in bloodstream infections (BSIs) represent a serious clinical challenge. In this study, the aim is to assess the incidence of resistance to novel β-lactams-β-lactamase inhibitor combinations (βL-βLICs), such as ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MER-VAB) and imipenem-relebactam (IMI-REL), in KPC-Kp strains collected during a three-year period from patients with bacteremia. KPC-Kp strains resistant to βL-βLICs were selected for whole-genome sequencing. A total of 133 K. pneumoniae strains were isolated, and KPC-Kp strains were the most represented (87.2%). In 2018, resistance to CAZ-AVI and MER-VAB was 6.5% and 14.5%, respectively. In 2019, KPC-Kp resistance to CAZ-AVI and MER-VAB remained at low levels, with values of 12.9% and 3.2%, respectively. During 2020, CAZ-AVI resistance was detected in 2/23 of KPC-Kp strains (8.7%). IMI-REL was the most active βL-βLIC, inhibiting >98% of the isolates, while CAZ-AVI and MER-VAB inhibited 87−93% and 85−97% of the KPC producers, respectively. Correlations between genotypic traits and resistance to βL-βLICs showed that KPC-Kp strains resistant to CAZ-AVI harbored a mutation within the blaKPC-3 gene, while all KPC-Kp strains resistant to CAZ-AVI, MER-VAB and/or IMI-REL carried the blaKPC-3 gene. Moreover, genetic analysis of porin genes showed that 14/16 of KPC-Kp resistant isolates possessed a truncated OmpK35 and glycine (G) and aspartic acid (D) insertions at positions 134−135 within OmpK36, whereas 2/16 displayed truncated OmpK35 and OmpK36 porins. Novel βL-βLICs are promising agents against KPC-Kp infections; however, the emergence of resistance to these agents highlights the need for continuous surveillance and application of enhanced antimicrobial stewardship.
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Affiliation(s)
| | | | | | | | - Paolo Gaibani
- Correspondence: ; Tel.: +39-051-2144316; Fax: +39-051-2143076
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3
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Nishimura T, Kawahara T, Kagaya N, Ogura Y, Takikawa H, Suenaga H, Adachi M, Hirokawa T, Doi T, Shin-Ya K. JBIR-155, a Specific Class D β-Lactamase Inhibitor of Microbial Origin. Org Lett 2021; 23:4415-4419. [PMID: 34029112 DOI: 10.1021/acs.orglett.1c01352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We discovered JBIR-155 as a novel specific class D β-lactamase inhibitor from Streptomyces polymachus SoB100815Hv02. JBIR-155 consists of a 6-oxabicyclo[3.2.0]heptan-7-one skeleton and a long unsaturated alkyl chain moiety of which absolute configuration was determined by spectroscopic data, modified Mosher's method, and analyses of the relative configuration of chemically modified derivative. JBIR-155 specifically exhibited inhibitory activity against the class D β-lactamase, with an IC50 value of 0.36 μM.
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Affiliation(s)
- Takehiro Nishimura
- Technology Research Association for Next Generation Natural Products Chemistry, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Teppei Kawahara
- Japan Biological Informatics Consortium (JBIC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064 Japan
| | - Noritaka Kagaya
- Technology Research Association for Next Generation Natural Products Chemistry, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Yusuke Ogura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hirosato Takikawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hikaru Suenaga
- National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
| | - Masaatsu Adachi
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Takatsugu Hirokawa
- National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.,Division of Biomedical Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.,Transborder Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Takayuki Doi
- Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Kazuo Shin-Ya
- Technology Research Association for Next Generation Natural Products Chemistry, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.,National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.,Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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4
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Yadav TC, Agarwal V, Srivastava AK, Raghuwanshi N, Varadwaj P, Prasad R, Pruthi V. Insight into Structure-Function Relationships of β-Lactamase and BLIPs Interface Plasticity using Protein-Protein Interactions. Curr Pharm Des 2020; 25:3378-3389. [PMID: 31544712 DOI: 10.2174/1381612825666190911154650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/05/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Mostly BLIPs are identified in soil bacteria Streptomyces and originally isolated from Streptomyces clavuligerus and can be utilized as a model system for biophysical, structural, mutagenic and computational studies. BLIP possess homology with two proteins viz., BLIP-I (Streptomyces exofoliatus) and BLP (beta-lactamase inhibitory protein like protein from S. clavuligerus). BLIP consists of 165 amino acid, possessing two homologues domains comprising helix-loop-helix motif packed against four stranded beta-sheet resulting into solvent exposed concave surface with extended four stranded beta-sheet. BLIP-I is a 157 amino acid long protein obtained from S. exofoliatus having 37% sequence identity to BLIP and inhibits beta-lactamase. METHODS This review is intended to briefly illustrate the beta-lactamase inhibitory activity of BLIP via proteinprotein interaction and aims to open up a new avenue to combat antimicrobial resistance using peptide based inhibition. RESULTS D49A mutation in BLIP-I results in a decrease in affinity for TEM-1 from 0.5 nM to 10 nM (Ki). It is capable of inhibiting TEM-1 and bactopenemase and differs from BLIP only in modulating cell wall synthesis enzyme. Whereas, BLP is a 154 amino acid long protein isolated from S. clavuligerus via DNA sequencing analysis of Cephamycin-Clavulanate gene bunch. It shares 32% sequence similarity with BLIP and 42% with BLIP-I. Its biological function is unclear and lacks beta-lactamase inhibitory activity. CONCLUSION Protein-protein interactions mediate a significant role in regulation and modulation of cellular developments and processes. Specific biological markers and geometric characteristics are manifested by active site binding clefts of protein surfaces which determines the specificity and affinity for their targets. TEM1.BLIP is a classical model to study protein-protein interaction. β-Lactamase inhibitory proteins (BLIPs) interacts and inhibits various β-lactamases with extensive range of affinities.
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Affiliation(s)
- Tara C Yadav
- Department of Biotechnology, Indian Institute of Technology, Roorkee-247667, Uttarakhand, India
| | - Vidhu Agarwal
- Department of Bioinformatics, Indian Institute of Information Technology, Allahabad 211015, India
| | - Amit K Srivastava
- Department of Biotechnology, Indian Institute of Technology, Roorkee-247667, Uttarakhand, India
| | - Navdeep Raghuwanshi
- Vaccine Formulation & Research Center, Gennova (Emcure) Biopharmaceuticals Limited, Pune - 11057, Maharashtra, India
| | - Pritish Varadwaj
- Department of Bioinformatics, Indian Institute of Information Technology, Allahabad 211015, India
| | - Ramasare Prasad
- Department of Biotechnology, Indian Institute of Technology, Roorkee-247667, Uttarakhand, India
| | - Vikas Pruthi
- Department of Biotechnology, Indian Institute of Technology, Roorkee-247667, Uttarakhand, India
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5
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Zhou Y, Guo Y, Wen Z, Ci X, Xia L, Wang Y, Deng X, Wang J. Isoalantolactone Enhances the Antimicrobial Activity of Penicillin G against Staphylococcus aureus by Inactivating β-lactamase during Protein Translation. Pathogens 2020; 9:pathogens9030161. [PMID: 32110983 PMCID: PMC7157633 DOI: 10.3390/pathogens9030161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/22/2020] [Accepted: 02/25/2020] [Indexed: 12/23/2022] Open
Abstract
β-Lactamase-positive Staphylococcus aureus is one of the most prevalent multidrug-resistant pathogens worldwide and is associated with increasing threats to clinical therapeutics and public health. Here, we showed that isoalantolactone (IAL), in combination with penicillin G, exhibited significant synergism against 21 β-lactamase-positive S. aureus strains (including methicillin resistant S. aureus). An enzyme inhibition assay, a checkerboard minimum inhibitory concentration (MIC) assay, a growth curve assay, a time-killing assay, a RT-PCR assay and Circular Dichroism (CD) spectroscopy were performed on different β-lactamases or β-lactamase-positive S. aureus strains, in vitro, to confirm the mechanism of inhibition of β-lactamase and the synergistic effects of the combination of penicillin G and IAL. All the fractional inhibitory concentration (FIC) indices of penicillin G, in combination with IAL, against β-lactamase-positive S. aureus, were less than 0.5, and ranged from 0.10 ± 0.02 to 0.38 ± 0.17. The survival rate of S. aureus-infected mice increased significantly from 35.29% to 88.24% within 144 h following multiple compound therapy approaches. Unlike sulbactam, IAL inactivated β-lactamase during protein translation, and the therapeutic effect of combination therapy with IAL and penicillin G was equivalent to that of sulbactam with penicillin G. Collectively, our results indicated that IAL is a promising and leading drug that can be used to restore the antibacterial effect of β-lactam antibiotics such as penicillin G and to address the inevitable infection caused by βlactamase-positive S. aureus.
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Affiliation(s)
- Yonglin Zhou
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China;
| | - Yan Guo
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China;
| | - Zhongmei Wen
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
| | - Xinxin Ci
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
| | - Lining Xia
- College of Veterinary Medicine, Xinjiang Agricultural University, Urmuqi 830052, China;
| | - Yanling Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China;
| | - Xuming Deng
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China;
- Correspondence: (X.D.); (J.W.); Tel.: +86 431-87836161 (X.D.); +86 431-87835385 (J.W.); Fax: +86 431-87836160 (X.D.); +86 431-87836160 (J.W.)
| | - Jianfeng Wang
- Department of Respiratory Medicine, the First Hospital of Jilin University, Changchun 130021, China; (Y.Z.); (Y.G.); (Z.W.); (X.C.)
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun 130062, China;
- Correspondence: (X.D.); (J.W.); Tel.: +86 431-87836161 (X.D.); +86 431-87835385 (J.W.); Fax: +86 431-87836160 (X.D.); +86 431-87836160 (J.W.)
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6
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Parida P, Bhowmick S, Saha A, Islam MA. Insight into the screening of potential beta-lactamase inhibitors as anti-bacterial chemical agents through pharmacoinformatics study. J Biomol Struct Dyn 2020; 39:923-942. [PMID: 31984863 DOI: 10.1080/07391102.2020.1720819] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Drug resistance is an unsolved and major concern in the bacterial infection. Continuous development of drug-resistance to the antibiotics exponentially rises the danger of bacterial infections. Chemical components from the plants are becoming a major resource of potentially effective therapeutic chemical agents for the wide range of diseases including bacterial infections. In the current study, pharmacoinformatics methodologies were implemented on more than two hundred known phytochemicals to find promising beta-lactamase inhibitors for therapeutically effective anti-bacterial agents. Initially, the molecular docking-based score was used to reduce the chemical space of the selected dataset. Fourteen molecules were found to have more affinity towards the beta-lactamase in compared to the well-known anti-bacterial agent, Avibactam. Binding interactions analysis revealed the strong binding interactions between phytochemicals and catalytic amino residues. For further analysis, molecular dynamics (MD) simulations, density functional theory (DFT) and in silico pharmacokinetics studies were performed. Parameters from MD simulations studies suggested that selected molecules are strong enough to retain in the active site in different orientations of the beta-lactamase. The orbital energies obtained from the DFT study was undoubtedly explained the potentiality of the selected compounds for being effective beta-lactamase inhibitors. The drug-likeness and acceptable pharmacokinetics parameters were observed using in silico ADME analysis. Therefore, observations from the multiple pharmacoinformatics approach explained without any doubt that selected molecules are potential enough being promising anti-bacterial compounds. [Formula: see text] Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Pratap Parida
- School of Medical Science and Technology, Indian Institute of Technology, Kharagpur, India
| | - Shovonlal Bhowmick
- Department of Chemical Technology, University of Calcutta, Kolkata, India
| | - Achintya Saha
- Department of Chemical Technology, University of Calcutta, Kolkata, India
| | - Md Ataul Islam
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,School of Health Sciences, University of Kwazulu-Natal, Durban, South Africa.,Department of Chemical Pathology, Faculty of Health Sciences, University of Pretoria and National Health Laboratory Service Tshwane Academic Division, Pretoria, South Africa
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7
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Douafer H, Andrieu V, Phanstiel O, Brunel JM. Antibiotic Adjuvants: Make Antibiotics Great Again! J Med Chem 2019; 62:8665-8681. [PMID: 31063379 DOI: 10.1021/acs.jmedchem.8b01781] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Multiple approaches have been developed to combat bacterial resistance. However, the combination of antibiotic resistance mechanisms by bacteria and the limited number of effective antibiotics available decreases the effective interventions for the treatment of current bacterial infections. This review covers the many ways that bacteria resist antibiotics including antibiotic target modification, the use of efflux pumps, and antibiotic inactivation. As a pertinent example, the use of beta lactamase inhibitors in combination with β-lactam containing antibiotics is discussed in detail. The solution to emerging antibiotic resistance may involve combination therapies of existing antibiotics and potentiating adjuvants, which re-empower the antibiotic agent to become efficacious against the resistant strain of interest. We report herein that a reasoned adjuvant design permits one to perform polypharmacy on bacteria by not only providing greater internal access to the codosed antibiotics but also by de-energizing the efflux pumps used by the bacteria to escape antibiotic action.
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Affiliation(s)
- Hana Douafer
- Aix Marseille University , INSERM, SSA, MCT , 13385 Marseille , France
| | - Véronique Andrieu
- Aix Marseille University , IRD, APHM, MEPHI, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie , 13385 Marseille , France
| | - Otto Phanstiel
- 12722 Research Parkway, College of Medicine , University of Central Florida , Orlando , Florida 32826 , United States
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8
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Tackling the Antibiotic Resistance Caused by Class A β-Lactamases through the Use of β-Lactamase Inhibitory Protein. Int J Mol Sci 2018; 19:ijms19082222. [PMID: 30061509 PMCID: PMC6121496 DOI: 10.3390/ijms19082222] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 07/23/2018] [Accepted: 07/25/2018] [Indexed: 12/27/2022] Open
Abstract
β-Lactams are the most widely used and effective antibiotics for the treatment of infectious diseases. Unfortunately, bacteria have developed several mechanisms to combat these therapeutic agents. One of the major resistance mechanisms involves the production of β-lactamase that hydrolyzes the β-lactam ring thereby inactivating the drug. To overcome this threat, the small molecule β-lactamase inhibitors (e.g., clavulanic acid, sulbactam and tazobactam) have been used in combination with β-lactams for treatment. However, the bacterial resistance to this kind of combination therapy has evolved recently. Therefore, multiple attempts have been made to discover and develop novel broad-spectrum β-lactamase inhibitors that sufficiently work against β-lactamase producing bacteria. β-lactamase inhibitory proteins (BLIPs) (e.g., BLIP, BLIP-I and BLIP-II) are potential inhibitors that have been found from soil bacterium Streptomyces spp. BLIPs bind and inhibit a wide range of class A β-lactamases from a diverse set of Gram-positive and Gram-negative bacteria, including TEM-1, PC1, SME-1, SHV-1 and KPC-2. To the best of our knowledge, this article represents the first systematic review on β-lactamase inhibitors with a particular focus on BLIPs and their inherent properties that favorably position them as a source of biologically-inspired drugs to combat antimicrobial resistance. Furthermore, an extensive compilation of binding data from β-lactamase–BLIP interaction studies is presented herein. Such information help to provide key insights into the origin of interaction that may be useful for rationally guiding future drug design efforts.
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9
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van den Akker F, Bonomo RA. Exploring Additional Dimensions of Complexity in Inhibitor Design for Serine β-Lactamases: Mechanistic and Intra- and Inter-molecular Chemistry Approaches. Front Microbiol 2018; 9:622. [PMID: 29675000 PMCID: PMC5895744 DOI: 10.3389/fmicb.2018.00622] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/19/2018] [Indexed: 01/14/2023] Open
Abstract
As a bacterial resistance strategy, serine β-lactamases have evolved from cell wall synthesizing enzymes known as penicillin-binding proteins (PBP), by not only covalently binding β-lactam antibiotics but, also acquiring mechanisms of deacylating these antibiotics. This critical deacylation step leads to release of hydrolyzed and inactivated β-lactams, thereby providing resistance for the bacteria against these antibiotics targeting the cell wall. To combat β-lactamase-mediated antibiotic resistance, numerous β-lactamase inhibitors were developed that utilize various strategies to inactivate the β-lactamase. Most of these compounds are “mechanism-based” inhibitors that in some manner mimic the β-lactam substrate, having a carbonyl moiety and a negatively charged carboxyl or sulfate group. These compounds form a covalent adduct with the catalytic serine via an initial acylation step. To increase the life-time of the inhibitory covalent adduct intermediates, a remarkable array of different strategies was employed to improve inhibition potency. Such approaches include post-acylation intra- and intermolecular chemical rearrangements as well as affecting the deacylation water. These approaches transform the inhibitor design process from a 3-dimensional problem (i.e., XYZ coordinates) to one with additional dimensions of complexity as the reaction coordinate and time spent at each chemical state need to be taken into consideration. This review highlights the mechanistic intricacies of the design efforts of the β-lactamase inhibitors which so far have resulted in the development of “two generations” and 5 clinically available inhibitors.
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Affiliation(s)
- Focco van den Akker
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Robert A Bonomo
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Medicine, Pharmacology, Molecular Biology and Microbiology, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Medical Service and Geriatric Research, Education, and Clinical Centers (GRECC), Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, United States.,Case Western Reserve University-VA Medical Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH, United States
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10
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Structure activity relationship studies on rhodanines and derived enethiol inhibitors of metallo-β-lactamases. Bioorg Med Chem 2018; 26:2928-2936. [PMID: 29655609 PMCID: PMC6008492 DOI: 10.1016/j.bmc.2018.02.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 12/14/2022]
Abstract
Metallo-β-lactamases (MBLs) enable bacterial resistance to almost all classes of β-lactam antibiotics. We report studies on enethiol containing MBL inhibitors, which were prepared by rhodanine hydrolysis. The enethiols inhibit MBLs from different subclasses. Crystallographic analyses reveal that the enethiol sulphur displaces the di-Zn(II) ion bridging ‘hydrolytic’ water. In some, but not all, cases biophysical analyses provide evidence that rhodanine/enethiol inhibition involves formation of a ternary MBL enethiol rhodanine complex. The results demonstrate how low molecular weight active site Zn(II) chelating compounds can inhibit a range of clinically relevant MBLs and provide additional evidence for the potential of rhodanines to be hydrolysed to potent inhibitors of MBL protein fold and, maybe, other metallo-enzymes, perhaps contributing to the complex biological effects of rhodanines. The results imply that any medicinal chemistry studies employing rhodanines (and related scaffolds) as inhibitors should as a matter of course include testing of their hydrolysis products.
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11
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Werner JP, Mitchell JM, Taracila MA, Bonomo RA, Powers RA. Exploring the potential of boronic acids as inhibitors of OXA-24/40 β-lactamase. Protein Sci 2017; 26:515-526. [PMID: 27997706 DOI: 10.1002/pro.3100] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/08/2016] [Accepted: 12/08/2016] [Indexed: 01/01/2023]
Abstract
β-lactam antibiotics are crucial to the management of bacterial infections in the medical community. Due to overuse and misuse, clinically significant bacteria are now resistant to many commercially available antibiotics. The most widespread resistance mechanism to β-lactams is the expression of β-lactamase enzymes. To overcome β-lactamase mediated resistance, inhibitors were designed to inactivate these enzymes. However, current inhibitors (clavulanic acid, tazobactam, and sulbactam) for β-lactamases also contain the characteristic β-lactam ring, making them susceptible to resistance mechanisms employed by bacteria. This presents a critical need for novel, non-β-lactam inhibitors that can circumvent these resistance mechanisms. The carbapenem-hydrolyzing class D β-lactamases (CHDLs) are of particular concern, given that they efficiently hydrolyze potent carbapenem antibiotics. Unfortunately, these enzymes are not inhibited by clinically available β-lactamase inhibitors, nor are they effectively inhibited by the newest, non-β-lactam inhibitor, avibactam. Boronic acids are known transition state analog inhibitors of class A and C β-lactamases, and are not extensively characterized as inhibitors of class D β-lactamases. Importantly, boronic acids provide a novel way to potentially inhibit class D β-lactamases. Sixteen boronic acids were selected and tested for inhibition of the CHDL OXA-24/40. Several compounds were identified as effective inhibitors of OXA-24/40, with Ki values as low as 5 μM. The X-ray crystal structures of OXA-24/40 in complex with BA3, BA4, BA8, and BA16 were determined and revealed the importance of interactions with hydrophobic residues Tyr112 and Trp115. These boronic acids serve as progenitors in optimization efforts of a novel series of inhibitors for class D β-lactamases.
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Affiliation(s)
- Josephine P Werner
- Department of Chemistry, Grand Valley State University, Allendale, Michigan, 49401
| | - Joshua M Mitchell
- Department of Chemistry, Grand Valley State University, Allendale, Michigan, 49401
| | - Magdalena A Taracila
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, 44106.,Departments of Medicine, Pharmacology, Biochemistry and Molecular Biology, and Microbiology, Case Western Reserve University, Cleveland, Ohio, 44106
| | - Robert A Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, 44106.,Departments of Medicine, Pharmacology, Biochemistry and Molecular Biology, and Microbiology, Case Western Reserve University, Cleveland, Ohio, 44106
| | - Rachel A Powers
- Department of Chemistry, Grand Valley State University, Allendale, Michigan, 49401
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12
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Simakov N, Leonard DA, Smith JC, Wymore T, Szarecka A. A Distal Disulfide Bridge in OXA-1 β-Lactamase Stabilizes the Catalytic Center and Alters the Dynamics of the Specificity Determining Ω Loop. J Phys Chem B 2016; 121:3285-3296. [PMID: 27668669 DOI: 10.1021/acs.jpcb.6b07884] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Widespread antibiotic resistance, particularly when mediated by broad-spectrum β-lactamases, has major implications for public health. Substitutions in the active site often allow broad-spectrum enzymes to accommodate diverse types of β-lactams. Substitutions observed outside the active site are thought to compensate for the loss of thermal stability. The OXA-1 clade of class D β-lactamases contains a pair of conserved cysteines located outside the active site that forms a disulfide bond in the periplasm. Here, the effect of the distal disulfide bond on the structure and dynamics of OXA-1 was investigated via 4 μs molecular dynamics simulations. The results reveal that the disulfide promotes the preorganized orientation of the catalytic residues and affects the conformation of the functionally important Ω loop. Furthermore, principal component analysis reveals differences in the global dynamics between the oxidized and reduced forms, especially in the motions involving the Ω loop. A dynamical network analysis indicates that, in the oxidized form, in addition to its role in ligand binding, the KTG family motif is a central hub of the global dynamics. As activity of OXA-1 has been measured only in the reduced form, we suggest that accurate assessment of its functional profile would require oxidative conditions mimicking periplasm.
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Affiliation(s)
- Nikolay Simakov
- Carnegie Mellon University , Pittsburgh Supercomputing Center, Pittsburgh, Pennsylvania 15213, United States.,Center for Computational Research, SUNY at Buffalo , New York 14203, United States
| | | | - Jeremy C Smith
- Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Troy Wymore
- Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.,Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
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13
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Wang DY, Abboud MI, Markoulides MS, Brem J, Schofield CJ. The road to avibactam: the first clinically useful non-β-lactam working somewhat like a β-lactam. Future Med Chem 2016; 8:1063-84. [PMID: 27327972 DOI: 10.4155/fmc-2016-0078] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023] Open
Abstract
Avibactam, which is the first non-β-lactam β-lactamase inhibitor to be introduced for clinical use, is a broad-spectrum serine β-lactamase inhibitor with activity against class A, class C, and, some, class D β-lactamases. We provide an overview of efforts, which extend to the period soon after the discovery of the penicillins, to develop clinically useful non-β-lactam compounds as antibacterials, and, subsequently, penicillin-binding protein and β-lactamase inhibitors. Like the β-lactam inhibitors, avibactam works via a mechanism involving covalent modification of a catalytically important nucleophilic serine residue. However, unlike the β-lactam inhibitors, avibactam reacts reversibly with its β-lactamase targets. We discuss chemical factors that may account for the apparently special nature of β-lactams and related compounds as antibacterials and β-lactamase inhibitors, including with respect to resistance. Avenues for future research including non-β-lactam antibacterials acting similarly to β-lactams are discussed.
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Affiliation(s)
| | | | | | - Jürgen Brem
- Department of Chemistry, University of Oxford, UK
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14
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Identification of peptide inhibitors of penicillinase using a phage display library. Anal Biochem 2016; 494:4-9. [DOI: 10.1016/j.ab.2015.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/18/2015] [Accepted: 10/21/2015] [Indexed: 12/20/2022]
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15
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Rajamäki SHM, De Luca L, Capitta F, Porcheddu A. A telescopic one-pot synthesis of β-lactam rings using amines as a convenient source of imines. RSC Adv 2016. [DOI: 10.1039/c6ra02744j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A facile synthetic approach to substituted β-lactams was designed, using secondary benzylic amines and acid chlorides as starting materials. The reactions proceeded smoothly and all the products were obtained in good yields.
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Affiliation(s)
- Suvi H. M. Rajamäki
- Università degli Studi di Sassari
- Dipartimento di Chimica e Farmacia
- Sassari
- Italy
| | - Lidia De Luca
- Università degli Studi di Sassari
- Dipartimento di Chimica e Farmacia
- Sassari
- Italy
| | - Francesca Capitta
- Università degli Studi di Sassari
- Dipartimento di Chimica e Farmacia
- Sassari
- Italy
| | - Andrea Porcheddu
- Università degli Studi di Cagliari
- Dipartimento di Scienze Chimiche e Geologiche
- Cittadella Universitaria
- 09042 Monserrato
- Italy
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16
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Insight into the effect of inhibitor resistant S130G mutant on physico-chemical properties of SHV type beta-lactamase: a molecular dynamics study. PLoS One 2014; 9:e112456. [PMID: 25479359 PMCID: PMC4257546 DOI: 10.1371/journal.pone.0112456] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 10/14/2014] [Indexed: 11/29/2022] Open
Abstract
Bacterial resistance is a serious threat to human health. The production of β-lactamase, which inactivates β-lactams is most common cause of resistance to the β-lactam antibiotics. The Class A enzymes are most frequently encountered among the four β-lactamases in the clinic isolates. Mutations in class A β-lactamases play a crucial role in substrate and inhibitor specificity. SHV and TEM type are known to be most common class A β-lactamases. In the present study, we have analyzed the effect of inhibitor resistant S130G point mutation of SHV type Class-A β-lactamase using molecular dynamics and other in silico approaches. Our study involved the use of different in silico methods to investigate the affect of S130G point mutation on the major physico-chemical properties of SHV type class A β-lactamase. We have used molecular dynamics approach to compare the dynamic behaviour of native and S130G mutant form of SHV β-lactamase by analyzing different properties like root mean square deviation (RMSD), H-bond, Radius of gyration (Rg) and RMS fluctuation of mutation. The results clearly suggest notable loss in the stability of S130G mutant that may further lead to decrease in substrate specificity of SHV. Molecular docking further indicates that S130G mutation decreases the binding affinity of all the three inhibitors in clinical practice.
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17
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Leonard DA, Bonomo RA, Powers RA. Class D β-lactamases: a reappraisal after five decades. Acc Chem Res 2013; 46:2407-15. [PMID: 23902256 DOI: 10.1021/ar300327a] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Despite 70 years of clinical use, β-lactam antibiotics still remain at the forefront of antimicrobial chemotherapy. The major challenge to these life-saving therapeutics is the presence of bacterial enzymes (i.e., β-lactamases) that can hydrolyze the β-lactam bond and inactivate the antibiotic. These enzymes can be grouped into four classes (A-D). Among the most genetically diverse are the class D β-lactamases. In this class are β-lactamases that can inactivate the entire spectrum of β-lactam antibiotics (penicillins, cephalosporins, and carbapenems). Class D β-lactamases are mostly found in Gram-negative bacteria such as Pseudomonas aeruginosa , Escherichia coli , Proteus mirabilis , and Acinetobacter baumannii . The active-sites of class D β-lactamases contain an unusual N-carboxylated lysine post-translational modification. A strongly hydrophobic active-site helps create the conditions that allow the lysine to combine with CO2, and the resulting carbamate is stabilized by a number of hydrogen bonds. The carboxy-lysine plays a symmetric role in the reaction, serving as a general base to activate the serine nucleophile in the acylation reaction, and the deacylating water in the second step. There are more than 250 class D β-lactamases described, and the full set of variants shows remarkable diversity with regard to substrate binding and turnover. Narrow-spectrum variants are most effective against the earliest generation penicillins and cephalosporins such as ampicillin and cephalothin. Extended-spectrum variants (also known as extended-spectrum β-lactamases, ESBLs) pose a more dangerous clinical threat as they possess a small number of substitutions that allow them to bind and hydrolyze later generation cephalosporins that contain bulkier side-chain constituents (e.g., cefotaxime, ceftazidime, and cefepime). Mutations that permit this versatility seem to cluster in the area surrounding an active-site tryptophan resulting in a widened active-site to accommodate the oxyimino side-chains of these cephalosporins. More concerning are the class D β-lactamases that hydrolyze clinically important carbapenem β-lactam drugs (e.g., imipenem). Whereas carbapenems irreversibly acylate and inhibit narrow-spectrum β-lactamases, class D carbapenemases are able to recruit and activate a deacylating water. The rotational orientation of the C6 hydroxyethyl group found on all carbapenem antibiotics likely plays a role in whether the deacylating water is effective or not. Inhibition of class D β-lactamases is a current challenge. Commercially available inhibitors that are active against other classes of β-lactamases are ineffective against class D enzymes. On the horizon are several compounds, consisting of both β-lactam derivatives and non-β-lactams, that have the potential of providing novel leads to design new mechanism-based inactivators that are effective against the class D enzymes. Several act synergistically when given in combination with a β-lactam antibiotic, and others show a unique mechanism of inhibition that is distinct from the traditional β-lactamase inhibitors. These studies will bolster structure-based inhibitor design efforts to facilitate the optimization and development of these compounds as class D inactivators.
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Affiliation(s)
- David A. Leonard
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, United States
| | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and Department of Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, United States
| | - Rachel A. Powers
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, United States
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18
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Hamed RB, Gomez-Castellanos JR, Henry L, Ducho C, McDonough MA, Schofield CJ. The enzymes of β-lactam biosynthesis. Nat Prod Rep 2013; 30:21-107. [DOI: 10.1039/c2np20065a] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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19
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Substitutions at position 105 in SHV family β-lactamases decrease catalytic efficiency and cause inhibitor resistance. Antimicrob Agents Chemother 2012; 56:5678-86. [PMID: 22908166 DOI: 10.1128/aac.00711-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ambler position 105 in class A β-lactamases is implicated in resistance to clavulanic acid, although no clinical isolates with mutations at this site have been reported. We hypothesized that Y105 is important in resistance to clavulanic acid because changes in positioning of the inhibitor for ring oxygen protonation could occur. In addition, resistance to bicyclic 6-methylidene penems, which are interesting structural probes that inhibit all classes of serine β-lactamases with nanomolar affinity, might emerge with substitutions at position 105, especially with nonaromatic substitutions. All 19 variants of SHV-1 with variations at position 105 were prepared. Antimicrobial susceptibility testing showed that Escherichia coli DH10B expressing Y105 variants retained activity against ampicillin, except for the Y105L variant, which was susceptible to all β-lactams, similar to the case for the host control strain. Several variants had elevated MICs to ampicillin-clavulanate. However, all the variants remained susceptible to piperacillin in combination with a penem inhibitor (MIC, ≤2/4 mg/liter). The Y105E, -F, -M, and -R variants demonstrated reduced catalytic efficiency toward ampicillin compared to the wild-type (WT) enzyme, which was caused by increased K(m). Clavulanic acid and penem K(i) values were also increased for some of the variants, especially Y105E. Mutagenesis at position 105 in SHV yields mutants resistant to clavulanate with reduced catalytic efficiency for ampicillin and nitrocefin, similar to the case for the class A carbapenemase KPC-2. Our modeling analyses suggest that resistance is due to oxyanion hole distortion. Susceptibility to a penem inhibitor is retained although affinity is decreased, especially for the Y105E variant. Residue 105 is important to consider when designing new inhibitors.
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20
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Chan FY, Neves MAC, Sun N, Tsang MW, Leung YC, Chan TH, Abagyan R, Wong KY. Validation of the AmpC β-Lactamase Binding Site and Identification of Inhibitors with Novel Scaffolds. J Chem Inf Model 2012; 52:1367-75. [DOI: 10.1021/ci300068m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fung-Yi Chan
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
| | - Marco A. C. Neves
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
- Centro de Neurociências,
Lab. Química Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, Pólo das Ciências
da Saúde, 3000-548 Coimbra, Portugal
| | - Ning Sun
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
| | - Man-Wah Tsang
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
| | - Yun-Chung Leung
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
| | - Tak-Hang Chan
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
| | - Ruben Abagyan
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Kwok-Yin Wong
- Department
of Applied Biology
and Chemical Technology and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon,
Hong Kong, P. R. China
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21
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Hamed RB, Henry L, Gomez-Castellanos JR, Mecinović J, Ducho C, Sorensen JL, Claridge TDW, Schofield CJ. Crotonase Catalysis Enables Flexible Production of Functionalized Prolines and Carbapenams. J Am Chem Soc 2011; 134:471-9. [DOI: 10.1021/ja208318d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Refaat B. Hamed
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
- Department of Pharmacognosy, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Luc Henry
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | | | - Jasmin Mecinović
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Christian Ducho
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - John L. Sorensen
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Timothy D. W. Claridge
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Christopher J. Schofield
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
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22
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Page MGP, Dantier C, Desarbre E, Gaucher B, Gebhardt K, Schmitt-Hoffmann A. In vitro and in vivo properties of BAL30376, a β-lactam and dual beta-lactamase inhibitor combination with enhanced activity against Gram-negative Bacilli that express multiple β-lactamases. Antimicrob Agents Chemother 2011; 55:1510-9. [PMID: 21245441 PMCID: PMC3067176 DOI: 10.1128/aac.01370-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/03/2010] [Accepted: 01/07/2011] [Indexed: 11/20/2022] Open
Abstract
BAL30376 is a triple combination comprising a siderophore monobactam, BAL19764; a novel bridged monobactam, BAL29880, which specifically inhibits class C β-lactamases; and clavulanic acid, which inhibits many class A and some class D β-lactamases. The MIC(90) was ≤ 4 μg/ml (expressed as the concentration of BAL19764) for most species of the Enterobacteriaceae family, including strains that produced metallo-β-lactamases and were resistant to all of the other β-lactams tested. The MIC(90) for Stenotrophomonas maltophilia was 2 μg/ml, for multidrug-resistant (MDR) Pseudomonas aeruginosa it was 8 μg/ml, and for MDR Acinetobacter and Burkholderia spp. it was 16 μg/ml. The presence of the class C β-lactamase inhibitor BAL29880 contributed significantly to the activity of BAL30376 against strains of Citrobacter freundii, Enterobacter species, Serratia marcescens, and P. aeruginosa. The presence of clavulanic acid contributed significantly to the activity against many strains of Escherichia coli and Klebsiella pneumoniae that produced class A extended-spectrum β-lactamases. The activity of BAL30376 against strains with metallo-β-lactamases was largely attributable to the intrinsic stability of the monobactam BAL19764 toward these enzymes. Considering its three components, BAL30376 was unexpectedly refractory toward the development of stable resistance.
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Affiliation(s)
- Malcolm G P Page
- Basilea Pharmaceutica International Ltd., PO Box 3255, CH-4005 Basel, Switzerland.
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23
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Papp-Wallace KM, Taracila M, Wallace CJ, Hujer KM, Bethel CR, Hornick JM, Bonomo RA. Elucidating the role of Trp105 in the KPC-2 β-lactamase. Protein Sci 2011; 19:1714-27. [PMID: 20662006 DOI: 10.1002/pro.454] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The molecular basis of resistance to β-lactams and β-lactam-β-lactamase inhibitor combinations in the KPC family of class A enzymes is of extreme importance to the future design of effective β-lactam therapy. Recent crystal structures of KPC-2 and other class A β-lactamases suggest that Ambler position Trp105 may be of importance in binding β-lactam compounds. Based on this notion, we explored the role of residue Trp105 in KPC-2 by conducting site-saturation mutagenesis at this position. Escherichia coli DH10B cells expressing the Trp105Phe, -Tyr, -Asn, and -His KPC-2 variants possessed minimal inhibitory concentrations (MICs) similar to E. coli cells expressing wild type (WT) KPC-2. Interestingly, most of the variants showed increased MICs to ampicillin-clavulanic acid but not to ampicillin-sulbactam or piperacillin-tazobactam. To explain the biochemical basis of this behavior, four variants (Trp105Phe, -Asn, -Leu, and -Val) were studied in detail. Consistent with the MIC data, the Trp105Phe β-lactamase displayed improved catalytic efficiencies, k(cat)/K(m), toward piperacillin, cephalothin, and nitrocefin, but slightly decreased k(cat)/K(m) toward cefotaxime and imipenem when compared to WT β-lactamase. The Trp105Asn variant exhibited increased K(m)s for all substrates. In contrast, the Trp105Leu and -Val substituted enzymes demonstrated notably decreased catalytic efficiencies (k(cat)/K(m)) for all substrates. With respect to clavulanic acid, the K(i)s and partition ratios were increased for the Trp105Phe, -Asn, and -Val variants. We conclude that interactions between Trp105 of KPC-2 and the β-lactam are essential for hydrolysis of substrates. Taken together, kinetic and molecular modeling studies define the role of Trp105 in β-lactam and β-lactamase inhibitor discrimination.
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24
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Carey PR, Chen Y, Gong B, Kalp M. Kinetic crystallography by Raman microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:742-9. [PMID: 20797452 DOI: 10.1016/j.bbapap.2010.08.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 08/12/2010] [Accepted: 08/16/2010] [Indexed: 11/16/2022]
Abstract
Raman spectra, obtained using a Raman microscope, offer a unique and incisive approach to follow interactions and reactions inside a single crystal under soak-in or soak-out conditions. The utility of this approach derives from the finding that the Raman spectra from single macromolecular crystals, under normal (non-resonance) conditions, are extremely stable, with a low "light background," and provide ideal platforms for Raman difference spectroscopy. In turn, this allows the interrogation of sub-molecular changes in very large and complex macromolecular environments. There is often great synergy with X-ray crystallography, with the Raman spectroscopist providing crystallography colleagues with the best soak-in conditions to generate a targeted intermediate for flash freezing and X-ray analysis. On the other hand, X-ray structures at points along a reaction pathway provide invaluable benchmarks for interpreting the Raman data from populations seen by Raman to be changing in real-time. These principles will be illustrated by two reactions: the first involves a complex, branching reaction pathway underlying the inhibition of β-lactamases by clinically important pharmaceutical compounds, where different combinations of drug and enzyme function in different regions of the pathway. The second shows how temporal data can be derived for several events in the initiation step of RNA synthesis-more specifically, when one GTP molecule is joined to one ATP molecule to form a G∙A dimer in the active site of a 115,000 Dalton crystalline RNA polymerase. Finally, we will summarize the extension of Raman microscopy to nucleic acid crystals and the information that has been obtained for RNA-based enzymes. This article is part of a Special Issue entitled: Protein Structure and Function in the Crystalline State.
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Affiliation(s)
- Paul R Carey
- Case Western Reserve University, Department of Biochemistry, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
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25
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Abstract
Since the introduction of penicillin, beta-lactam antibiotics have been the antimicrobial agents of choice. Unfortunately, the efficacy of these life-saving antibiotics is significantly threatened by bacterial beta-lactamases. beta-Lactamases are now responsible for resistance to penicillins, extended-spectrum cephalosporins, monobactams, and carbapenems. In order to overcome beta-lactamase-mediated resistance, beta-lactamase inhibitors (clavulanate, sulbactam, and tazobactam) were introduced into clinical practice. These inhibitors greatly enhance the efficacy of their partner beta-lactams (amoxicillin, ampicillin, piperacillin, and ticarcillin) in the treatment of serious Enterobacteriaceae and penicillin-resistant staphylococcal infections. However, selective pressure from excess antibiotic use accelerated the emergence of resistance to beta-lactam-beta-lactamase inhibitor combinations. Furthermore, the prevalence of clinically relevant beta-lactamases from other classes that are resistant to inhibition is rapidly increasing. There is an urgent need for effective inhibitors that can restore the activity of beta-lactams. Here, we review the catalytic mechanisms of each beta-lactamase class. We then discuss approaches for circumventing beta-lactamase-mediated resistance, including properties and characteristics of mechanism-based inactivators. We next highlight the mechanisms of action and salient clinical and microbiological features of beta-lactamase inhibitors. We also emphasize their therapeutic applications. We close by focusing on novel compounds and the chemical features of these agents that may contribute to a "second generation" of inhibitors. The goal for the next 3 decades will be to design inhibitors that will be effective for more than a single class of beta-lactamases.
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Affiliation(s)
- Sarah M. Drawz
- Departments of Pathology, Medicine, Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | - Robert A. Bonomo
- Departments of Pathology, Medicine, Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio
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Inhibitor resistance in the KPC-2 beta-lactamase, a preeminent property of this class A beta-lactamase. Antimicrob Agents Chemother 2009; 54:890-7. [PMID: 20008772 DOI: 10.1128/aac.00693-09] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
As resistance determinants, KPC beta-lactamases demonstrate a wide substrate spectrum that includes carbapenems, oxyimino-cephalosporins, and cephamycins. In addition, clinical strains harboring KPC-type beta-lactamases are often identified as resistant to standard beta-lactam-beta-lactamase inhibitor combinations in susceptibility testing. The KPC-2 carbapenemase presents a significant clinical challenge, as the mechanistic bases for KPC-2-associated phenotypes remain elusive. Here, we demonstrate resistance by KPC-2 to beta-lactamase inhibitors by determining that clavulanic acid, sulbactam, and tazobactam are hydrolyzed by KPC-2 with partition ratios (kcat/kinact ratios, where kinact is the rate constant of enzyme inactivation) of 2,500, 1,000, and 500, respectively. Methylidene penems that contain an sp2-hybridized C3 carboxylate and a bicyclic R1 side chain (dihydropyrazolo[1,5-c][1,3]thiazole [penem 1] and dihydropyrazolo[5,1-c][1,4]thiazine [penem 2]) are potent inhibitors: Km of penem 1, 0.06+/-0.01 microM, and Km of penem 2, 0.006+/-0.001 microM. We also demonstrate that penems 1 and 2 are mechanism-based inactivators, having partition ratios (kcat/kinact ratios) of 250 and 50, respectively. To understand the mechanism of inhibition by these penems, we generated molecular representations of both inhibitors in the active site of KPC-2. These models (i) suggest that penem 1 and penem 2 interact differently with active site residues, with the carbonyl of penem 2 being positioned outside the oxyanion hole and in a less favorable position for hydrolysis than that of penem 1, and (ii) support the kinetic observations that penem 2 is the better inhibitor (kinact/Km=6.5+/-0.6 microM(-1) s(-1)). We conclude that KPC-2 is unique among class A beta-lactamases in being able to readily hydrolyze clavulanic acid, sulbactam, and tazobactam. In contrast, penem-type beta-lactamase inhibitors, by exhibiting unique active site chemistry, may serve as an important scaffold for future development and offer an attractive alternative to our current beta-lactamase inhibitors.
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Alimirzaee P, Gohari AR, Hajiaghaee R, Mirzaee S, Jamalifar H, Monsef-Esfahani HR, Amin G, Saeidnia S, Shahverdi AR. 1-methyl malate from Berberis integerrima fruits enhances the antibacterial activity of ampicillin against Staphylococcus aureus. Phytother Res 2009; 23:797-800. [PMID: 19172582 DOI: 10.1002/ptr.2641] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The enhancement of the antibacterial activity of ampicillin by different extracts of Berberis integerrima fruits was evaluated against Staphylococcus aureus. Disk diffusion and agar dilution methods were used to determine the antibacterial activity of ampicillin in the absence and presence of different plant extracts or various fractions eluted by column chromatography. A clinical isolate of S. aureus was used as a test strain. The active component of B. integerrima fruits involved in the enhancement of ampicillin activity was purified and identified as 1-methyl malate using different spectroscopic methods. Both the ethanol extract of B. integerrima fruits and 1-methyl malate enhanced the antibacterial activity of ampicillin. The total extract as well as 1-methyl malate increased the antibacterial activity of ampicillin against the test strain. The potency of ampicillin against the test strain was increased 64-fold when tested with a sub-toxic concentration of total extract of B. integerrima fruits. Also, 1-methyl malate increased the bactericidal activity of ampicillin. In the presence of 2 mg/mL of 1-methyl malate the MIC of ampicillin for S. aureus decreased from 128 to 1 microg/mL (128-fold).
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Affiliation(s)
- P Alimirzaee
- Pharmaceutical Research Unit, Azad University, Tehran, Iran
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28
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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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29
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Iqbal A, Clifton IJ, Bagonis M, Kershaw NJ, Domene C, Claridge TDW, Wharton CW, Schofield CJ. Anatomy of a Simple Acyl Intermediate in Enzyme Catalysis: Combined Biophysical and Modeling Studies on Ornithine Acetyl Transferase. J Am Chem Soc 2008; 131:749-57. [DOI: 10.1021/ja807215u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aman Iqbal
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Ian J. Clifton
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Maria Bagonis
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Nadia J. Kershaw
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Carmen Domene
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Timothy D. W. Claridge
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Christopher W. Wharton
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Christopher J. Schofield
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K., Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, U.K., School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
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30
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Beck J, Gharbi S, Herteg-Fernea A, Vercheval L, Bebrone C, Lassaux P, Zervosen A, Marchand-Brynaert J. Aminophosphonic Acids and Aminobis(phosphonic acids) as Potential Inhibitors of Penicillin-Binding Proteins. European J Org Chem 2008. [DOI: 10.1002/ejoc.200800812] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Kalp M, Carey PR. Carbapenems and SHV-1 beta-lactamase form different acyl-enzyme populations in crystals and solution. Biochemistry 2008; 47:11830-7. [PMID: 18922024 DOI: 10.1021/bi800833u] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactions between single crystals of the SHV-1 beta-lactamase enzyme and the carbapenems, meropenem, imipenem, and ertapenem, have been studied by Raman microscopy. Aided by quantum mechanical calculations, major populations of two acyl-enzyme species, a labile Delta (2)-pyrroline and a more tightly bound Delta (1)-pyrroline, have been identified for all three compounds. These isomers differ only in the position of the double bond about the carbapenem nucleus. This discovery is consonant with X-ray crystallographic findings that also identified two populations for meropenem bound in SHV-1: one with the acyl CO group in the oxyanion hole and the second with the acyl group rotated 180 degrees compared to its expected position [Nukaga, M., Bethel, C. R., Thomson, J. M., Hujer, A. M., Distler, A. M., Anderson, V. E., Knox, J. R., and Bonomo, R. A. (2008) J. Am. Chem. Soc. (in press)]. When crystals of the Delta (1)- and Delta (2)-containing acyl-enzymes were exposed to solutions with no carbapenem, rapid deacylation of the Delta (2) species was observed by kinetic Raman experiments. However, no change in the Delta (1) population was observed over 1 h, the effective lifetime of the crystal. These observations lead to the hypothesis that the stable Delta (1) species is due to the form seen by X-ray with the acyl carbonyl outside the oxyanion hole, while the Delta (2) species corresponds to the form with the carbonyl inside the oxyanion hole. Soak-in and soak-out Raman experiments also demonstrated that tautomeric exchange between the Delta (1) and Delta (2) forms does not occur on the crystalline enzyme. When meropenem or ertapenem was reacted with SHV-1 in solution, the Raman difference spectra demonstrated that only a major population corresponding to the Delta (1) acyl-enzyme could be detected. The 1003 cm (-1) mode of the phenyl ring positioned on the C3 side chain of ertapenem acts as an effective internal Raman intensity standard, and the ratio of its intensity to that of the 1600 cm (-1) feature of Delta (1) provides an estimate of the relative populations of Delta (1). In solution, I 1600/ I 1003 equals 2, and in the crystal, I 1600 /I 1003 equals 1. This is strong evidence that the Delta (1) and Delta (2) acyl-enzymes in the crystal are present in approximately equal amounts, in agreement with the X-ray data. However, in solution there are twice as many Delta (1) species per Phe group, and this represents approximately 100% of the active sites, which is consistent with the observed inhibition of the enzyme's activity.
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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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32
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Johnson JW, Evanoff DP, Savard ME, Lange G, Ramadhar TR, Assoud A, Taylor NJ, Dmitrienko GI. Cyclobutanone Mimics of Penicillins: Effects of Substitution on Conformation and Hemiketal Stability. J Org Chem 2008; 73:6970-82. [PMID: 18710291 DOI: 10.1021/jo801274m] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jarrod W. Johnson
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Darryl P. Evanoff
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Marc E. Savard
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Gerald Lange
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Timothy R. Ramadhar
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Abdeljalil Assoud
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Nicholas J. Taylor
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
| | - Gary I. Dmitrienko
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1
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33
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Kalp M, Sheri A, Buynak JD, Bethel CR, Bonomo RA, Carey PR. Efficient inhibition of class A and class D beta-lactamases by Michaelis complexes. J Biol Chem 2007; 282:21588-91. [PMID: 17561511 DOI: 10.1074/jbc.c700080200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A 6-alkylidiene penam sulfone, SA-1-204, is an efficient inhibitor of both SHV-1 and OXA-1 beta-lactamases with K(I) = 42 +/- 4 nm and 1.0 +/- 0.1 microm, respectively. To gain insight into the reaction chemistry of SA-1-204, the reactions between this inhibitor and SHV-1 and OXA-1 were studied by Raman spectroscopy in single crystals and in solution. Raman signatures characteristic of the unreacted beta-lactam ring show that in both phases the inhibitor binds as a noncovalent Michaelis-like complex. This complex is present as the major population for periods of up to an hour. On longer time scales, the Raman data show that beta-lactam ring opening eventually leads to a complex mixture of reaction products. However, the data clearly demonstrate that the key species for inhibition on the time scale of bacterial half-lives is the noncovalent complex preceding acylation.
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Affiliation(s)
- Matthew Kalp
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA
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34
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Bethel CR, Hujer AM, Hujer KM, Thomson JM, Ruszczycky MW, Anderson VE, Pusztai-Carey M, Taracila M, Helfand MS, Bonomo RA. Role of Asp104 in the SHV beta-lactamase. Antimicrob Agents Chemother 2006; 50:4124-31. [PMID: 16982784 PMCID: PMC1694000 DOI: 10.1128/aac.00848-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Among the TEM-type extended-spectrum beta-lactamases (ESBLs), an amino acid change at Ambler position 104 (Glu to Lys) results in increased resistance to ceftazidime and cefotaxime when found with other substitutions (e.g., Gly238Ser and Arg164Ser). To examine the role of Asp104 in SHV beta-lactamases, site saturation mutagenesis was performed. Our goal was to investigate the properties of amino acid residues at this position that affect resistance to penicillins and oxyimino-cephalosporins. Unexpectedly, 58% of amino acid variants at position 104 in SHV expressed in Escherichia coli DH10B resulted in beta-lactamases with lowered resistance to ampicillin. In contrast, increased resistance to cefotaxime was demonstrated only for the Asp104Arg and Asp104Lys beta-lactamases. When all 19 substitutions were introduced into the SHV-2 (Gly238Ser) ESBL, the most significant increases in cefotaxime and ceftazidime resistance were noted for both the doubly substituted Asp104Lys Gly238Ser and the doubly substituted Asp104Arg Gly238Ser beta-lactamases. Correspondingly, the overall catalytic efficiency (kcat/Km) of hydrolysis for cefotaxime was increased from 0.60 +/- 0.07 microM(-1) s(-1) (mean +/- standard deviation) for Gly238Ser to 1.70 +/- 0.01 microM(-1) s(-1) for the Asp104Lys and Gly238Ser beta-lactamase (threefold increase). We also showed that (i) k3 was the rate-limiting step for the hydrolysis of cefotaxime by Asp104Lys, (ii) the Km for cefotaxime of the doubly substituted Asp104Lys Gly238Ser variant approached that of the Gly238Ser beta-lactamase as pH increased, and (iii) Lys at position 104 functions in an energetically additive manner with the Gly238Ser substitution to enhance catalysis of cephalothin. Based on this analysis, we propose that the amino acid at Ambler position 104 in SHV-1 beta-lactamase plays a major role in substrate binding and recognition of oxyimino-cephalosporins and influences the interactions of Tyr105 with penicillins.
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Affiliation(s)
- Christopher R Bethel
- Louis Stokes Cleveland Veterans Affairs Medical Center, 10701 East Blvd., Cleveland, OH 44106, USA
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35
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Affiliation(s)
- Paul R Carey
- Department of Biochemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
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36
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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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37
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Phillips OA. β-Lactamase inhibitors: a survey of the patent literature 2000 – 2004. Expert Opin Ther Pat 2006. [DOI: 10.1517/13543776.16.3.319] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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38
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Adediran SA, Nukaga M, Baurin S, Frère JM, Pratt RF. Inhibition of class D beta-lactamases by acyl phosphates and phosphonates. Antimicrob Agents Chemother 2006; 49:4410-2. [PMID: 16189136 PMCID: PMC1251531 DOI: 10.1128/aac.49.10.4410-4412.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The susceptibility of typical class D beta-lactamases to inhibition by acyl phosph(on)ates has been determined. To a large degree, these class D enzymes behaved very similarly to the class A TEM beta-lactamase towards these reagents. Dibenzoyl phosphate stood out in both cases as a lead compound towards a new class of effective inhibitors.
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Affiliation(s)
- S A Adediran
- Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA
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39
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Buynak JD. Understanding the longevity of the beta-lactam antibiotics and of antibiotic/beta-lactamase inhibitor combinations. Biochem Pharmacol 2005; 71:930-40. [PMID: 16359643 DOI: 10.1016/j.bcp.2005.11.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 11/02/2005] [Accepted: 11/10/2005] [Indexed: 10/25/2022]
Abstract
Microbial resistance necessitates the search for new targets and new antibiotics. However, it is likely that resistance problems will eventually threaten these new products and it may, therefore, be instructive to review the successful employment of beta-lactam antibiotic/beta-lactamase inhibitor combinations to combat penicillin resistance. These combination drugs have proven successful for more than two decades, with inhibitor resistance still being relatively rare. The beta-lactamase inhibitors are mechanism-based irreversible inactivators. The ability of the inhibitors to avoid resistance may be due to the structural similarities between the substrate and inhibitor.
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Affiliation(s)
- John D Buynak
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314, USA.
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40
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Georgopapadakou NH. β-Lactamase inhibitors: evolving compounds for evolving resistance targets. Expert Opin Investig Drugs 2005; 13:1307-18. [PMID: 15461559 DOI: 10.1517/13543784.13.10.1307] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The many and diverse beta-lactamases produced by bacteria, particularly by Gram-negative pathogens, are increasingly posing a serious threat to the clinical utility of beta-lactams. First-generation inhibitors (clavulanic acid, sulbactam, tazobactam) focus on Ambler class A enzymes. However, recent structural upgrades of class A beta-lactamases (e.g. TEM, SHV) have extended their spectrum (extended-spectrum beta-lactamases and carbapenemases [Sme, NMC-A, IMI-1]) and have brought about the possibility of beta-lactamase-inhibitor resistance. Furthermore, the mobilisation and spread of originally chromosomal class C enzymes (CMY, MIR), the growing clinical importance of class B enzymes (IMP, VIM), the emergence of inhibitor-resistant, broad spectrum class D (OXA) enzymes and the co-existence of different classes of beta-lactamases in the same pathogen have spurred research toward universal inhibitors. A complicating issue is target accessibility in Gram-negative bacteria, particularly in Enterobacter, Acinetobacter, Pseudomonas, Stenotrophomonas and other organisms, which is necessary in order for the inhibitor to synergise with vulnerable beta-lactam antibiotics. Several new, broad-spectrum inhibitors have emerged: cephem sulfones and oxapenems are upgrades of penam sulfones and oxapenams, respectively, with cephem sulfones possibly extending their inhibition to class B metallo-enzymes; and boronates and phosphonates are designed de novo, based on common structural and mechanistic features of serine beta-lactamases.
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Doucet N, De Wals PY, Pelletier JN. Site-saturation mutagenesis of Tyr-105 reveals its importance in substrate stabilization and discrimination in TEM-1 beta-lactamase. J Biol Chem 2004; 279:46295-303. [PMID: 15326193 DOI: 10.1074/jbc.m407606200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The conserved Class A beta-lactamase active site residue Tyr-105 was substituted by saturation mutagenesis in TEM-1 beta-lactamase from Escherichia coli in order to clarify its role in enzyme activity and in substrate stabilization and discrimination. Minimum inhibitory concentrations were calculated for E. coli cells harboring each Y105X mutant in the presence of various penicillin and cephalosporin antibiotics. We found that only aromatic residues as well as asparagine replacements conferred high in vivo survival rates for all substrates tested. At position 105, the small residues alanine and glycine provide weak substrate discrimination as evidenced by the difference in benzylpenicillin hydrolysis relative to cephalothin, two typical penicillin and cephalosporin antibiotics. Kinetic analyses of mutants of interest revealed that the Y105X replacements have a greater effect on K(m) than k(cat), highlighting the importance of Tyr-105 in substrate recognition. Finally, by performing a short molecular dynamics study on a restricted set of Y105X mutants of TEM-1, we found that the strong aromatic bias observed at position 105 in Class A beta-lactamases is primarily defined by a structural requirement, selecting planar residues that form a stabilizing wall to the active site. The adopted conformation of residue 105 prevents detrimental steric interactions with the substrate molecule in the active site cavity and provides a rationalization for the strong aromatic bias found in nature at this position among Class A beta-lactamases.
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Affiliation(s)
- Nicolas Doucet
- Département de Biochimie and Département de chimie, Université de Montréal, C. P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
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Pagan-Rodriguez D, Zhou X, Simmons R, Bethel CR, Hujer AM, Helfand MS, Jin Z, Guo B, Anderson VE, Ng LM, Bonomo RA. Tazobactam Inactivation of SHV-1 and the Inhibitor-resistant Ser130 → Gly SHV-1 β-Lactamase. J Biol Chem 2004; 279:19494-501. [PMID: 14757767 DOI: 10.1074/jbc.m311669200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The increasing number of bacteria resistant to combinations of beta-lactam and beta-lactamase inhibitors is creating great difficulties in the treatment of serious hospital-acquired infections. Understanding the mechanisms and structural basis for the inactivation of these inhibitor-resistant beta-lactamases provides a rationale for the design of novel compounds. In the present work, SHV-1 and the Ser(130) --> Gly inhibitor-resistant variant of SHV-1 beta-lactamase were inactivated with tazobactam, a potent class A beta-lactamase inhibitor. Apoenzymes and inhibited beta-lactamases were analyzed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS), digested with trypsin, and the products resolved using LC-ESI/MS and matrix-assisted laser desorption ionization-time of flight mass spectrometry. The mass increases observed for SHV-1 and Ser(130) --> Gly (+ Delta 88 Da and + Delta 70 Da, respectively) suggest that fragmentation of tazobactam readily occurs in the inhibitor-resistant variant to yield an inactive beta-lactamase. These two mass increments are consistent with the formation of an aldehyde (+ Delta 70 Da) and a hydrated aldehyde (+ Delta 88 Da) as stable products of inhibition. Our results reveal that the Ser --> Gly substitution at amino acid position 130 is not essential for enzyme inactivation. By examining the inhibitor-resistant Ser(130) --> Gly beta-lactamase, our data are the first to show that tazobactam undergoes fragmentation while still attached to the active site Ser(70) in this enzyme. After acylation of tazobactam by Ser(130) --> Gly, inactivation proceeds independent of any additional covalent interactions.
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Affiliation(s)
- Doritza Pagan-Rodriguez
- Department of Chemistry, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
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43
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Bethel CR, Hujer AM, Helfand MS, Bonomo RA. Exploring the effectiveness of tazobactam against ceftazidime resistant Escherichia coli: insights from the comparison between susceptibility testing and β-lactamase inhibition. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09519.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Stone GW, Zhang Q, Castillo R, Doppalapudi VR, Bueno AR, Lee JY, Li Q, Sergeeva M, Khambatta G, Georgopapadakou NH. Mechanism of action of NB2001 and NB2030, novel antibacterial agents activated by beta-lactamases. Antimicrob Agents Chemother 2004; 48:477-83. [PMID: 14742198 PMCID: PMC321519 DOI: 10.1128/aac.48.2.477-483.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two potent antibacterial agents designed to undergo enzyme-catalyzed therapeutic activation were evaluated for their mechanisms of action. The compounds, NB2001 and NB2030, contain a cephalosporin with a thienyl (NB2001) or a tetrazole (NB2030) ring at the C-7 position and are linked to the antibacterial triclosan at the C-3 position. The compounds exploit beta-lactamases to release triclosan through hydrolysis of the beta-lactam ring. Like cephalothin, NB2001 and NB2030 were hydrolyzed by class A beta-lactamases (Escherichia coli TEM-1 and, to a lesser degree, Staphylococcus aureus PC1) and class C beta-lactamases (Enterobacter cloacae P99 and E. coli AmpC) with comparable catalytic efficiencies (k(cat)/K(m)). They also bound to the penicillin-binding proteins of S. aureus and E. coli, but with reduced affinities relative to that of cephalothin. Accordingly, they produced a cell morphology in E. coli consistent with the toxophore rather than the beta-lactam being responsible for antibacterial activity. In biochemical assays, they inhibited the triclosan target enoyl reductase (FabI), with 50% inhibitory concentrations being markedly reduced relative to that of free triclosan. The transport of NB2001, NB2030, and triclosan was rapid, with significant accumulation of triclosan in both S. aureus and E. coli. Taken together, the results suggest that NB2001 and NB2030 act primarily as triclosan prodrugs in S. aureus and E. coli.
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Sarno R, Ha H, Weinsetel N, Tolmasky ME. Inhibition of aminoglycoside 6'-N-acetyltransferase type Ib-mediated amikacin resistance by antisense oligodeoxynucleotides. Antimicrob Agents Chemother 2004; 47:3296-304. [PMID: 14506044 PMCID: PMC201158 DOI: 10.1128/aac.47.10.3296-3304.2003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Amikacin has been very useful in the treatment of infections caused by multiresistant bacteria because it is refractory to the actions of most modifying enzymes. However, the spread of AAC(6')-I-type acetyltransferases, enzymes capable of catalyzing inactivation of amikacin, has rendered this antibiotic all but useless in some parts of the world. The aminoglycoside 6'-N-acetyltransferase type Ib, which is coded for by the aac(6')-Ib gene, mediates resistance to amikacin and other aminoglycosides. RNase H mapping and computer prediction of the secondary structure led to the identification of five regions accessible for interaction with antisense oligodeoxynucleotides in the aac(6')-Ib mRNA. Oligodeoxynucleotides targeting these regions could bind to native mRNA with different efficiencies and mediated RNase H digestion. Selected oligodeoxynucleotides inhibited AAC(6')-Ib synthesis in cell-free coupled transcription-translation assays. After their introduction into an Escherichia coli strain harboring aac(6')-Ib by electroporation, some of these oligodeoxynucleotides decreased the level of resistance to amikacin. Our results indicate that use of antisense compounds could be a viable strategy to preserve the efficacies of existing antibiotics to which bacteria are becoming increasingly resistant.
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MESH Headings
- Acetyltransferases/antagonists & inhibitors
- Acetyltransferases/genetics
- Acetyltransferases/metabolism
- Amikacin/pharmacology
- Base Sequence
- Binding Sites
- Cell-Free System
- Colony Count, Microbial
- Drug Resistance, Multiple, Bacterial/drug effects
- Drug Resistance, Multiple, Bacterial/genetics
- Drug Resistance, Multiple, Bacterial/physiology
- Enzyme Inhibitors/pharmacology
- Escherichia coli/drug effects
- Escherichia coli/genetics
- Molecular Sequence Data
- Nucleic Acid Conformation
- Oligonucleotides, Antisense/genetics
- Oligonucleotides, Antisense/metabolism
- Oligonucleotides, Antisense/pharmacology
- Protein Biosynthesis
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Ribonuclease H/metabolism
- Transcription, Genetic
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Affiliation(s)
- Renee Sarno
- Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California 92834-6850, USA
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Sun T, Nukaga M, Mayama K, Braswell EH, Knox JR. Comparison of beta-lactamases of classes A and D: 1.5-A crystallographic structure of the class D OXA-1 oxacillinase. Protein Sci 2003; 12:82-91. [PMID: 12493831 PMCID: PMC2312410 DOI: 10.1110/ps.0224303] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2002] [Revised: 10/08/2002] [Accepted: 10/09/2002] [Indexed: 01/25/2023]
Abstract
The crystallographic structure of the Escherichia coli OXA-1 beta-lactamase has been established at 1.5-A resolution and refined to R = 0.18. The 28.2-kD oxacillinase is a class D serine beta-lactamase that is especially active against the penicillin-type beta-lactams oxacillin and cloxacillin. In contrast to the structures of OXA-2, OXA-10, and OXA-13 belonging to other subclasses, the OXA-1 molecule is monomeric rather than dimeric and represents the subclass characterized by an enlarged Omega loop near the beta-lactam binding site. The 6-residue hydrophilic insertion in this loop cannot interact directly with substrates and, instead, projects into solvent. In this structure at pH 7.5, carboxylation of the conserved Lys 70 in the catalytic site is observed. One oxygen atom of the carboxylate group is hydrogen bonded to Ser 120 and Trp 160. The other oxygen atom is more exposed and hydrogen bonded to the Ogamma of the reactive Ser 67. In the overlay of the class D and class A binding sites, the carboxylate group is displaced ca. 2.6 A from the carboxylate group of Glu 166 of class A enzymes. However, each group is equidistant from the site of the water molecule expected to function in hydrolysis, and which could be activated by the carboxylate group of Lys 70. In this ligand-free OXA-1 structure, no water molecule is seen in this site, so the water molecule must enter after formation of the acyl-Ser 67 intermediate.
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Affiliation(s)
- Tao Sun
- Department of Molecular and Cell Biology, The University of Connecticut, Storrs, CT 06269, USA
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47
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Helfand MS, Hujer AM, Sönnichsen FD, Bonomo RA. Unexpected advanced generation cephalosporinase activity of the M69F variant of SHV beta-lactamase. J Biol Chem 2002; 277:47719-23. [PMID: 12354765 DOI: 10.1074/jbc.m207271200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Infections with bacteria that contain hydrolytic beta-lactamase enzymes are becoming a serious problem in the United States. Mutations at Met-69, an amino acid proximal to the active site Ser-70 in the TEM-1 and SHV-1 beta-lactamases, have emerged as a puzzling cause of bacterial resistance to inhibitors of beta-lactamases. Site-saturation mutagenesis of the 69 position in SHV beta-lactamase was performed to determine how mutations of this non-catalytic residue play a role in increasing 50% inhibitory concentrations (IC(50) concentrations) for clinically important beta-lactamase enzyme inhibitors. Two distinct phenotypes are evident in the variant beta-lactamases studied: significantly increased minimum inhibitory concentrations (microg/ml) and IC(50) concentrations to clavulanic acid for the Met69Ile, Leu, and Val substitutions, and unanticipated increased minimum inhibitory concentrations and hydrolytic activity toward ceftazidime, an advanced generation cephalosporin antibiotic, for the Met69Lys, Tyr- and Phe-substituted enzymes. Molecular modeling studies emphasize the conserved structure of these substitutions despite great variation in substrate specificity. This study demonstrates the key role of Met-69 in defining substrate specificity of SHV beta-lactamases and alerts us to new phenotypes that may emerge clinically.
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Affiliation(s)
- Marion S Helfand
- Infectious Disease Division, University Hospitals of Cleveland and Case Western Reserve University School of Medicine, Ohio 44106, USA
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Bonomo RA, Liu J, Chen Y, Ng L, Hujer AM, Anderson VE. Inactivation of CMY-2 beta-lactamase by tazobactam: initial mass spectroscopic characterization. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1547:196-205. [PMID: 11410275 DOI: 10.1016/s0167-4838(01)00175-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The CMY-2 beta-lactamase, a plasmid determined class C cephalosporinase, was shown to be susceptible to inhibition by tazobactam (K(i)=40 microM). The reaction product(s) of CMY-2 beta-lactamase with the beta-lactamase inhibitor tazobactam were analyzed by electrospray ionization/mass spectrometry (ESI/MS) to characterize the prominent intermediates of the inactivation pathway. The ESI/MS determined mass of CMY-2 beta-lactamase was 39851+/-3 Da. After inactivating CMY-2 beta-lactamase with excess tazobactam, a single species, M(r)=39931+/-3.0, was detected. Comparison of the peptide maps from tryptic digestion of the native enzyme and the inactivated beta-lactamase followed by LC/MS identified two 22 amino acid peptides containing the active site Ser64 modified by a fragment of tazobactam. These two peptides were increased in mass by 70 and 88 Da, respectively. UV difference spectra following inactivation revealed the presence of a new species with a 302 nm lambda(max). Based upon the increase in molecular mass of the tazobactam inactivated CMY-2 beta-lactamase, we propose that during the inactivation of this beta-lactamase by tazobactam an imine is formed. Tautomerization forms the spectrally observed enamine. Hydrolysis generates the covalently attached malonyl semialdehyde, its hydrate, or an enol. This work provides information on the mass of a stable enzyme intermediate of a class C beta-lactamase inactivated by tazobactam and, for the first time, unequivocal evidence that a cross-linked species is not required for apparent inactivation.
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Affiliation(s)
- R A Bonomo
- Infectious Disease Section, Louis Stokes Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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