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Deforet F, Carrière R, Dufour PL'A, Prat R, Desbiolles C, Cottin N, Reuzeau A, Dauwalder O, Dupieux-Chabert C, Tristan A, Cecchini T, Lemoine J, Vandenesch F. Proteomic assay for rapid characterisation of Staphylococcus aureus antimicrobial resistance mechanisms directly from blood cultures. Eur J Clin Microbiol Infect Dis 2024; 43:1329-1342. [PMID: 38750334 DOI: 10.1007/s10096-024-04811-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 03/11/2024] [Indexed: 07/20/2024]
Abstract
PURPOSE Staphylococcus aureus is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples. METHODS A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in S. aureus in the context of sepsis: PBP2a, PBP2c, APH(3')-III, ANT(4')-I, and AAC(6')-APH(2''), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124 S.aureus, accounting for the known genomic diversity of SCCmec types and the genetic background of the strains. RESULTS This method provided 99% agreement for PBP2a (n = 98/99 strains) detection. Agreement was 100% for PBP2c (n = 5/5), APH(3')-III (n = 16/16), and ANT(4')-I (n = 20/20), and 94% for AAC(6')-APH(2'') (n = 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4')-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the ant(4')-Ia gene. CONCLUSION The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of S. aureus resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.
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Affiliation(s)
- Francis Deforet
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Romain Carrière
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Pierre L 'Aour Dufour
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Roxane Prat
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Chloé Desbiolles
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Noémie Cottin
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Alicia Reuzeau
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Olivier Dauwalder
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Céline Dupieux-Chabert
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
| | - Anne Tristan
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Tiphaine Cecchini
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Jérôme Lemoine
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - François Vandenesch
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France.
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France.
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France.
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Abdulkadhim AH, Husein Kamona SM, Shamikh Al-Saedi HF, Taki AG, Hamoody AHM, Hamood SA, Rab SO, Amir AA, Kareem AT, Alawadi A, Ihsan A. Microwave-assisted synthesis and development of novel penicillinoate@copper metal-organic frameworks as a potent antibacterial agent. Front Chem 2024; 11:1331933. [PMID: 38274894 PMCID: PMC10808350 DOI: 10.3389/fchem.2023.1331933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024] Open
Abstract
Recently, nanoscience, especially metal-organic frameworks (MOFs), has been used to increase the effectiveness and properties of drugs. In this study, by using microwave irradiation; penicillin, which is a known antibiotic; and copper metal-organic frameworks (Cu-MOFs), a new penicillinoate@copper metal-organic framework (penicillinoate@Cu-MOF) was synthesized. The structure and characterization of the newly synthesized compound were determined using FT-IR spectrums, EDAX analysis, elemental analysis, XRD patterns, SEM images, nitrogen adsorption/desorption curves, and TGA curve. Then, its antimicrobial effects were evaluated on numerous Gram-positive and Gram-negative bacterial strains and were compared with those of penicillin and gentamicin. In continuation of the biological activities, antioxidant tests were performed on the compounds using the DPPH method. For biological activities, the synthesized penicillinoate@Cu-MOF is much more effective than penicillin and Cu-MOF. The loading of penicillin on the nanostructure and the presence of copper in the final composition can be attributed to the high antibiotic properties of the synthesized composition.
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Affiliation(s)
- Adnan Hashim Abdulkadhim
- Department of Computer Engineering, Technical Engineering College, Al-Ayen University, Thi-Qar, Iraq
| | | | | | - Anmar Ghanim Taki
- Department of Radiology and Sonar Techniques, Al-Noor University College, Nineveh, Iraq
| | | | - Sarah A. Hamood
- Department of Medical Engineering, Al-Esraa University College, Baghdad, Iraq
| | - Safia Obaidur Rab
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia
| | - Ahmed Ali Amir
- Department of Medical Laboratories Technology, AL-Nisour University College, Baghdad, Iraq
| | - Ashwaq Talib Kareem
- Department of Medical Engineering, College of Pharmacy, National University of Science and Technology, Dhi Qar, Iraq
| | - Ahmed Alawadi
- College of Technical Engineering, the Islamic University, Najaf, Iraq
- College of Technical Engineering, the Islamic University of Al Diwaniyah, Diwaniyah, Iraq
- College of Technical Engineering, the Islamic University of Babylon, Babylon, Iraq
| | - Ali Ihsan
- Department of Medical Laboratories Techniques, Imam Ja’afar Al‐Sadiq University, Al-Muthanna, Iraq
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3
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Jian Y, Li T, Zhao L, Zhao N, Liu Y, Lv H, Wang Y, Liu Q, Li M. Regulation of bla system in ST59-related oxacillin-susceptible mecA-positive Staphylococcus aureus. J Antimicrob Chemother 2021; 77:604-614. [PMID: 34918102 DOI: 10.1093/jac/dkab460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/10/2021] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVES Oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) is clinically significant and isolated globally but the mechanism of its occurrence remains indistinct. We sought to assess the mechanism of regulating oxacillin susceptibility in OS-MRSA isolates by evaluating the evolutionary dynamics of OS-MRSA and the discrepancies of mecA-regulating genes in OS-MRSA and oxacillin-resistant MRSA (OR-MRSA). METHODS Nine OS-MRSA isolates and 77 OR-MRSA isolates were sequenced using next-generation sequencing (NGS) platforms. Two representative OS-MRSA isolates (ET-13, ET-16) were induced to be oxacillin resistant and sequenced also. OS-MRSA ET-16 and its counterpart isolate with induced oxacillin resistance, ET-16I, and their mutants were used to confirm the role of the bla system in regulating methicillin susceptibility. Oxacillin MICs were determined using Etests. Expression of mecA and blaR1 was quantified by quantitative RT-PCR. RESULTS A deletion in blaR1 in most OS-MRSA isolates (7/9; 77.78%) was found using NGS data, and overexpression of OR-blaR1 in OS-MRSA isolate ET-16 restored its oxacillin resistance. OS-MRSA could be induced to be oxacillin resistant, while growth was suppressed in the induced isolates. Plasmid containing the bla locus was lost in most induced isolates during the induction process and complementation of blaR1-blaI from OS-MRSA ET-16 to the induced isolate ET-16I converted its oxacillin susceptibility. CONCLUSIONS Deletion in blaR1 resulted in oxacillin susceptibility in OS-MRSA, and loss of the bla regulator in OS-MRSA restored oxacillin resistance. The bla system played a crucial role in regulating oxacillin susceptibility in OS-MRSA isolates.
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Affiliation(s)
- Ying Jian
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Tianming Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Lin Zhao
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Na Zhao
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Yao Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Huiying Lv
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Ya'nan Wang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Qian Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Min Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
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Fisher JF, Mobashery S. β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium. Chem Rev 2021; 121:3412-3463. [PMID: 33373523 PMCID: PMC8653850 DOI: 10.1021/acs.chemrev.0c01010] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
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Kwiatkowski P, Łopusiewicz Ł, Pruss A, Kostek M, Sienkiewicz M, Bonikowski R, Wojciechowska-Koszko I, Dołęgowska B. Antibacterial Activity of Selected Essential Oil Compounds Alone and in Combination with β-Lactam Antibiotics Against MRSA Strains. Int J Mol Sci 2020; 21:ijms21197106. [PMID: 32993130 PMCID: PMC7582342 DOI: 10.3390/ijms21197106] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/22/2020] [Accepted: 09/25/2020] [Indexed: 12/21/2022] Open
Abstract
This study aimed to determine the effect of selected essential oil compounds (EOCs) on the antibacterial activity of β-lactam antibiotics (βLAs) against methicillin-resistant Staphylococcus aureus (MRSA) strains. The following parameters were studied: antibiotic susceptibility testing, detection of mecA gene and evaluation of genotypic relativity of isolates using molecular techniques, analysis of chemical composition applying Fourier-transform infrared (FTIR) spectroscopy, and determination of antibacterial activity of EOCs alone and in combination with βLAs against MRSA strains using microdilution and checkerboard methods. It was found that all isolates expressed MRSA and resistance phenotypes for macrolides, lincosamides, and streptogramins B. All isolates harbored the mecA gene and belonged to three distinct genotypes. Eight of the 10 EOCs showed efficient antimicrobial activity against the MRSA reference strain. The analysis of interaction between EOCs and βLAs against the MRSA reference strain revealed a synergistic and additive effect of the following combinations: methicillin (Met)-linalyl acetate (LinAc), penicillin G (Pen)-1,8-cineole (Cin), and Pen-LinAc. Analysis of EOC-βLA interactions showed a synergistic and additive effect in the following combinations: Met-LinAc (against low- and high-level βLAs resistance strains), Pen-Cin, and Pen-LinAc (against low-level βLAs resistance strains). It was also confirmed that changes in phosphodiester, -OH, -CH2 and -CH3 groups may change the interactions with βLAs. Moreover, the presence of two CH3O- moieties in the Met molecule could also play a key role in the synergistic and additive mechanism of LinAc action with Met against MRSA strains. Direct therapy using a Met-LinAc combination may become an alternative treatment method for staphylococcal infections caused by MRSA. However, this unconventional therapy must be preceded by numerous cytotoxicity tests.
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Affiliation(s)
- Paweł Kwiatkowski
- Department of Diagnostic Immunology, Chair of Microbiology, Immunology and Laboratory Medicine, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland;
- Correspondence: ; Tel.: +48-91-466-1659
| | - Łukasz Łopusiewicz
- Center of Bioimmobilisation and Innovative Packaging Materials, Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology Szczecin, Janickiego 35, 71-270 Szczecin, Poland; (Ł.Ł.); (M.K.)
| | - Agata Pruss
- Department of Laboratory Medicine, Chair of Microbiology, Immunology and Laboratory Medicine, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland; (A.P.); (B.D.)
| | - Mateusz Kostek
- Center of Bioimmobilisation and Innovative Packaging Materials, Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology Szczecin, Janickiego 35, 71-270 Szczecin, Poland; (Ł.Ł.); (M.K.)
| | - Monika Sienkiewicz
- Department of Allergology and Respiratory Rehabilitation, Medical University of Łódź, Żeligowskiego 7/9, 90-752 Łódź, Poland;
| | - Radosław Bonikowski
- Institute of General Food Chemistry, Faculty of Biotechnology and Food Sciences, Łódź University of Technology, Stefanowskiego 4/10, 90-924 Łódź, Poland;
| | - Iwona Wojciechowska-Koszko
- Department of Diagnostic Immunology, Chair of Microbiology, Immunology and Laboratory Medicine, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland;
| | - Barbara Dołęgowska
- Department of Laboratory Medicine, Chair of Microbiology, Immunology and Laboratory Medicine, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland; (A.P.); (B.D.)
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6
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Alexander JAN, Radaeva M, King DT, Chambers HF, Cherkasov A, Chatterjee SS, Strynadka NCJ. Structural analysis of avibactam-mediated activation of the bla and mec divergons in methicillin-resistant Staphylococcus aureus. J Biol Chem 2020; 295:10870-10884. [PMID: 32518158 DOI: 10.1074/jbc.ra120.013029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/02/2020] [Indexed: 02/01/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infections cause significant mortality and morbidity globally. MRSA resistance to β-lactam antibiotics is mediated by two divergons that control levels of a β-lactamase, PC1, and a penicillin-binding protein poorly acylated by β-lactam antibiotics, PBP2a. Expression of genes encoding these proteins is controlled by two integral membrane proteins, BlaR1 and MecR1, which both have an extracellular β-lactam-binding sensor domain. Here, we solved the X-ray crystallographic structures of the BlaR1 and MecR1 sensor domains in complex with avibactam, a diazabicyclooctane β-lactamase inhibitor at 1.6-2.0 Å resolution. Additionally, we show that S. aureus SF8300, a clinically relevant strain from the USA300 clone of MRSA, responds to avibactam by up-regulating the expression of the blaZ and pbp2a antibiotic-resistance genes, encoding PC1 and PBP2a, respectively. The BlaR1-avibactam structure of the carbamoyl-enzyme intermediate revealed that avibactam is bound to the active-site serine in two orientations ∼180° to each other. Although a physiological role of the observed alternative pose remains to be validated, our structural results hint at the presence of a secondary sulfate-binding pocket that could be exploited in the design of future inhibitors of BlaR1/MecR1 sensor domains or the structurally similar class D β-lactamases. The MecR1-avibactam structure adopted a singular avibactam orientation similar to one of the two states observed in the BlaR1-avibactam structure. Given avibactam up-regulates expression of blaZ and pbp2a antibiotic resistance genes, we suggest further consideration and research is needed to explore what effects administering β-lactam-avibactam combinations have on treating MRSA infections.
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Affiliation(s)
- J Andrew N Alexander
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Mariia Radaeva
- Vancouver Prostate Centre, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Dustin T King
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Henry F Chambers
- Division of Infectious Disease, Dept. of Medicine, San Francisco General Hospital, San Francisco, California, USA
| | - Artem Cherkasov
- Vancouver Prostate Centre, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Som S Chatterjee
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland and Institute of Marine and Environmental Technology, Baltimore, Maryland, USA ;
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver, British Columbia, Canada ;
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7
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Fisher JF, Mobashery S. Constructing and deconstructing the bacterial cell wall. Protein Sci 2020; 29:629-646. [PMID: 31747090 PMCID: PMC7021008 DOI: 10.1002/pro.3737] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/11/2022]
Abstract
The history of modern medicine cannot be written apart from the history of the antibiotics. Antibiotics are cytotoxic secondary metabolites that are isolated from Nature. The antibacterial antibiotics disproportionately target bacterial protein structure that is distinct from eukaryotic protein structure, notably within the ribosome and within the pathways for bacterial cell-wall biosynthesis (for which there is not a eukaryotic counterpart). This review focuses on a pre-eminent class of antibiotics-the β-lactams, exemplified by the penicillins and cephalosporins-from the perspective of the evolving mechanisms for bacterial resistance. The mechanism of action of the β-lactams is bacterial cell-wall destruction. In the monoderm (single membrane, Gram-positive staining) pathogen Staphylococcus aureus the dominant resistance mechanism is expression of a β-lactam-unreactive transpeptidase enzyme that functions in cell-wall construction. In the diderm (dual membrane, Gram-negative staining) pathogen Pseudomonas aeruginosa a dominant resistance mechanism (among several) is expression of a hydrolytic enzyme that destroys the critical β-lactam ring of the antibiotic. The key sensing mechanism used by P. aeruginosa is monitoring the molecular difference between cell-wall construction and cell-wall deconstruction. In both bacteria, the resistance pathways are manifested only when the bacteria detect the presence of β-lactams. This review summarizes how the β-lactams are sensed and how the resistance mechanisms are manifested, with the expectation that preventing these processes will be critical to future chemotherapeutic control of multidrug resistant bacteria.
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Affiliation(s)
- Jed F. Fisher
- Department of Chemistry and BiochemistryUniversity of Notre DameSouth BendIndiana
| | - Shahriar Mobashery
- Department of Chemistry and BiochemistryUniversity of Notre DameSouth BendIndiana
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8
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Belluzo BS, Abriata LA, Giannini E, Mihovilcevic D, Dal Peraro M, Llarrull LI. An experiment-informed signal transduction model for the role of the Staphylococcus aureus MecR1 protein in β-lactam resistance. Sci Rep 2019; 9:19558. [PMID: 31862951 PMCID: PMC6925264 DOI: 10.1038/s41598-019-55923-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 12/04/2019] [Indexed: 11/13/2022] Open
Abstract
The treatment of hospital- and community-associated infections by methicillin-resistant Staphylococcus aureus (MRSA) is a perpetual challenge. This Gram-positive bacterium is resistant specifically to β-lactam antibiotics, and generally to many other antibacterial agents. Its resistance mechanisms to β-lactam antibiotics are activated only when the bacterium encounters a β-lactam. This activation is regulated by the transmembrane sensor/signal transducer proteins BlaR1 and MecR1. Neither the transmembrane/metalloprotease domain, nor the complete MecR1 and BlaR1 proteins, are isolatable for mechanistic study. Here we propose a model for full-length MecR1 based on homology modeling, residue coevolution data, a new extensive experimental mapping of transmembrane topology, partial structures, molecular simulations, and available NMR data. Our model defines the metalloprotease domain as a hydrophilic transmembrane chamber effectively sealed by the apo-sensor domain. It proposes that the amphipathic helices inserted into the gluzincin domain constitute the route for transmission of the β-lactam-binding event in the extracellular sensor domain, to the intracellular and membrane-embedded zinc-containing active site. From here, we discuss possible routes for subsequent activation of proteolytic action. This study provides the first coherent model of the structure of MecR1, opening routes for future functional investigations on how β-lactam binding culminates in the proteolytic degradation of MecI.
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Affiliation(s)
- Bruno S Belluzo
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Predio CONICET Rosario, 27 de Febrero 210 bis, 2000, Rosario, Argentina
| | - Luciano A Abriata
- Laboratory for Biomolecular Modeling - École Polytechnique Fédérale de Lausanne and Swiss Institute of Bioinformatics, CH-1015, Lausanne, Switzerland
| | - Estefanía Giannini
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Predio CONICET Rosario, 27 de Febrero 210 bis, 2000, Rosario, Argentina
| | - Damila Mihovilcevic
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Predio CONICET Rosario, 27 de Febrero 210 bis, 2000, Rosario, Argentina
| | - Matteo Dal Peraro
- Laboratory for Biomolecular Modeling - École Polytechnique Fédérale de Lausanne and Swiss Institute of Bioinformatics, CH-1015, Lausanne, Switzerland
| | - Leticia I Llarrull
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Predio CONICET Rosario, 27 de Febrero 210 bis, 2000, Rosario, Argentina. .,Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 570, 2000, Rosario, Argentina.
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An assessment of antibacterial mode of action of chitosan on Listeria innocua cells using real-time HATR-FTIR spectroscopy. Int J Biol Macromol 2019; 135:386-393. [PMID: 31071397 DOI: 10.1016/j.ijbiomac.2019.05.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/03/2019] [Accepted: 05/05/2019] [Indexed: 11/23/2022]
Abstract
The antibacterial mode of action of chitosan using real-time, horizontal attenuated total reflectance, Fourier-transform infrared (HATR-FTIR) spectroscopy and transmission electron microscopy (TEM) was investigated. Listeria innocua was treated with chitosan solution. HATR-FTIR revealed an increased lethality and substantially metabolomics response on cell components. The main changes in FTIR and their 2nd derivative spectra were at 1045 cm-1 (carbohydrates in cell wall). Principal component analysis clearly segregated untreated and treated cells. Loadings plot revealed the functional groups in cell wall, cell membrane, phospholipid and protein regions of spectrum that are responsible for the classification of treated and control spectra. Kinetic traces of the metabolomics change suggested that cell wall and cell membrane seemed to be the initial target of the antimicrobial mechanism of chitosan. In agreement with the TEM images, which showed breakage of cell wall integrity. The cell wall, cell membrane, phospholipids, proteins and nucleic acids of FTIR spectral data recorded during the cell inactivation were shown to be linked to the metabolomics cell response in the lethality rate and structure of the cells. This work clearly showed, using HATR-FTIR spectroscopy, how bacteria can change their metabolomics response substantially during the first 45 min of contact time.
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Tooke CL, Hinchliffe P, Bragginton EC, Colenso CK, Hirvonen VHA, Takebayashi Y, Spencer J. β-Lactamases and β-Lactamase Inhibitors in the 21st Century. J Mol Biol 2019; 431:3472-3500. [PMID: 30959050 PMCID: PMC6723624 DOI: 10.1016/j.jmb.2019.04.002] [Citation(s) in RCA: 432] [Impact Index Per Article: 86.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/27/2019] [Accepted: 04/01/2019] [Indexed: 12/31/2022]
Abstract
The β-lactams retain a central place in the antibacterial armamentarium. In Gram-negative bacteria, β-lactamase enzymes that hydrolyze the amide bond of the four-membered β-lactam ring are the primary resistance mechanism, with multiple enzymes disseminating on mobile genetic elements across opportunistic pathogens such as Enterobacteriaceae (e.g., Escherichia coli) and non-fermenting organisms (e.g., Pseudomonas aeruginosa). β-Lactamases divide into four classes; the active-site serine β-lactamases (classes A, C and D) and the zinc-dependent or metallo-β-lactamases (MBLs; class B). Here we review recent advances in mechanistic understanding of each class, focusing upon how growing numbers of crystal structures, in particular for β-lactam complexes, and methods such as neutron diffraction and molecular simulations, have improved understanding of the biochemistry of β-lactam breakdown. A second focus is β-lactamase interactions with carbapenems, as carbapenem-resistant bacteria are of grave clinical concern and carbapenem-hydrolyzing enzymes such as KPC (class A) NDM (class B) and OXA-48 (class D) are proliferating worldwide. An overview is provided of the changing landscape of β-lactamase inhibitors, exemplified by the introduction to the clinic of combinations of β-lactams with diazabicyclooctanone and cyclic boronate serine β-lactamase inhibitors, and of progress and strategies toward clinically useful MBL inhibitors. Despite the long history of β-lactamase research, we contend that issues including continuing unresolved questions around mechanism; opportunities afforded by new technologies such as serial femtosecond crystallography; the need for new inhibitors, particularly for MBLs; the likely impact of new β-lactam:inhibitor combinations and the continuing clinical importance of β-lactams mean that this remains a rewarding research area.
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Affiliation(s)
- Catherine L Tooke
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Philip Hinchliffe
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Eilis C Bragginton
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Charlotte K Colenso
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Viivi H A Hirvonen
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Yuiko Takebayashi
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - James Spencer
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom.
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11
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Gillard K, Miller HB, Blackledge MS. Tricyclic amine antidepressants suppress β-lactam resistance in methicillin-resistant Staphylococcus aureus
(MRSA) by repressing mRNA levels of key resistance genes. Chem Biol Drug Des 2018; 92:1822-1829. [DOI: 10.1111/cbdd.13361] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 06/16/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Kyra Gillard
- Department of Chemistry; High Point University; High Point North Carolina
| | - Heather B. Miller
- Department of Chemistry; High Point University; High Point North Carolina
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12
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Hua X, Yang Q, Zhang W, Dong Z, Yu S, Schwarz S, Liu S. Antibacterial Activity and Mechanism of Action of Aspidinol Against Multi-Drug-Resistant Methicillin-Resistant Staphylococcus aureus. Front Pharmacol 2018; 9:619. [PMID: 29950995 PMCID: PMC6008372 DOI: 10.3389/fphar.2018.00619] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/23/2018] [Indexed: 12/03/2022] Open
Abstract
This study aimed at investigating the antibacterial activity of aspidinol, an extract from Dryopteris fragrans (L.) Schott, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA isolates were treated with aspidinol to determine the differential expression of genes and associated pathways following the drug treatment. Aspidinol displayed significant anti-MRSA activity, both in vivo (minimum inhibitory concentration = 2 μg/mL) and in vitro, and achieved an antibacterial effect comparable to that of vancomycin. In the lethal septicemic mouse study, a dose of 50 mg/kg of either aspidinol or vancomycin provided significant protection from mortality. In the non-lethal septicemic mouse study, aspidinol and vancomycin produced a significant reduction in mean bacterial load in murine organs, including the spleen, lung, and liver. After treatment with aspidinol, we found through RNA-seq and RT-PCR experiments that the inhibition of the formation of ribosomes was the primary S. aureus cell-killing mechanism, and the inhibition of amino acid synthesis and the reduction of virulence factors might play a secondary role.
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Affiliation(s)
- Xin Hua
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Qin Yang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Wanjiang Zhang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhimin Dong
- Tianjin Animal Science and Veterinary Research Institute, Tianjin, China
| | - Shenye Yu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Stefan Schwarz
- Institute of Microbiology and Epizootics, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Siguo Liu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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13
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Frederick TE, Peng JW. A gratuitous β-Lactamase inducer uncovers hidden active site dynamics of the Staphylococcus aureus BlaR1 sensor domain. PLoS One 2018; 13:e0197241. [PMID: 29771929 PMCID: PMC5957439 DOI: 10.1371/journal.pone.0197241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 04/28/2018] [Indexed: 11/18/2022] Open
Abstract
Increasing evidence shows that active sites of proteins have non-trivial conformational dynamics. These dynamics include active site residues sampling different local conformations that allow for multiple, and possibly novel, inhibitor binding poses. Yet, active site dynamics garner only marginal attention in most inhibitor design efforts and exert little influence on synthesis strategies. This is partly because synthesis requires a level of atomic structural detail that is frequently missing in current characterizations of conformational dynamics. In particular, while the identity of the mobile protein residues may be clear, the specific conformations they sample remain obscure. Here, we show how an appropriate choice of ligand can significantly sharpen our abilities to describe the interconverting binding poses (conformations) of protein active sites. Specifically, we show how 2-(2'-carboxyphenyl)-benzoyl-6-aminopenicillanic acid (CBAP) exposes otherwise hidden dynamics of a protein active site that binds β-lactam antibiotics. When CBAP acylates (binds) the active site serine of the β-lactam sensor domain of BlaR1 (BlaRS), it shifts the time scale of the active site dynamics to the slow exchange regime. Slow exchange enables direct characterization of inter-converting protein and bound ligand conformations using NMR methods. These methods include chemical shift analysis, 2-d exchange spectroscopy, off-resonance ROESY of the bound ligand, and reduced spectral density mapping. The active site architecture of BlaRS is shared by many β-lactamases of therapeutic interest, suggesting CBAP could expose functional motions in other β-lactam binding proteins. More broadly, CBAP highlights the utility of identifying chemical probes common to structurally homologous proteins to better expose functional motions of active sites.
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Affiliation(s)
- Thomas E. Frederick
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
| | - Jeffrey W. Peng
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
- Department of Physics, University of Notre Dame, Notre Dame, IN, United States of America
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14
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Prevalence of blaOXA-1 and blaDHA-1 AmpC β-Lactamase-Producing and Methicillin-Resistant Staphylococcus aureus in Iran. ARCHIVES OF PEDIATRIC INFECTIOUS DISEASES 2016. [DOI: 10.5812/pedinfect.36778] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Janardhanan J, Chang M, Mobashery S. The oxadiazole antibacterials. Curr Opin Microbiol 2016; 33:13-17. [PMID: 27239942 DOI: 10.1016/j.mib.2016.05.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/09/2016] [Accepted: 05/11/2016] [Indexed: 01/22/2023]
Abstract
The oxadiazoles are a class of antibacterials discovered by in silico docking and scoring of compounds against the X-ray structure of a penicillin-binding protein. These antibacterials exhibit activity against Gram-positive bacteria, including against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). They show in vivo efficacy in murine models of peritonitis/sepsis and neutropenic thigh MRSA infection. They are bactericidal and orally bioavailable. The oxadiazoles show promise in treatment of MRSA infection.
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Affiliation(s)
- Jeshina Janardhanan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States
| | - Mayland Chang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States.
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, United States.
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16
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Liu P, Xue H, Wu Z, Ma J, Zhao X. Effect ofblaregulators on the susceptible phenotype and phenotypic conversion for oxacillin-susceptiblemecA-positive staphylococcal isolates. J Antimicrob Chemother 2016; 71:2105-12. [DOI: 10.1093/jac/dkw123] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/14/2016] [Indexed: 11/14/2022] Open
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17
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Modulation of mecA Gene Expression by Essential Oil from Salvia sclarea and Synergism with Oxacillin in Methicillin Resistant Staphylococcus epidermidis Carrying Different Types of Staphylococcal Chromosomal Cassette mec. Int J Microbiol 2016; 2016:6475837. [PMID: 26880926 PMCID: PMC4736799 DOI: 10.1155/2016/6475837] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 12/05/2022] Open
Abstract
The essential oil (EO) from Salvia sclarea was shown to increase the susceptibility of methicillin resistant Staphylococcus epidermidis (MRSE) isolates to oxacillin. The purpose of this study was to investigate the effect of EO from S. sclarea on expression of mecA gene of MRSE carrying different types of staphylococcal chromosomal cassette (SCCmec) and to evaluate potential synergistic effect of EO with oxacillin. Using real-time PCR we found that EO alone inhibited the expression of the resistant genes mecA, mecR1, and mecI and blaZ, blaR1, and blaI. The use of the combination of EO with oxacillin resulted in significantly inhibited expression of mecA gene in all tested strains with different types of SCCmec. Using time-kill assay and checkerboard assay we confirmed synergistic effect of EO from S. sclarea and oxacillin in MRSE.
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18
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Staude MW, Frederick TE, Natarajan SV, Wilson BD, Tanner CE, Ruggiero ST, Mobashery S, Peng JW. Investigation of signal transduction routes within the sensor/transducer protein BlaR1 of Staphylococcus aureus. Biochemistry 2015; 54:1600-10. [PMID: 25658195 DOI: 10.1021/bi501463k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transmembrane antibiotic sensor/signal transducer protein BlaR1 is part of a cohort of proteins that confer β-lactam antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) [Fisher, J. F., Meroueh, S. O., and Mobashery, S. (2005) Chem. Rev. 105, 395-424; Llarrull, L. I., Fisher, J. F., and Mobashery, S. (2009) Antimicrob. Agents Chemother. 53, 4051-4063; Llarrull, L. I., Toth, M., Champion, M. M., and Mobashery, S. (2011) J. Biol. Chem. 286, 38148-38158]. Specifically, BlaR1 regulates the inducible expression of β-lactamases that hydrolytically destroy β-lactam antibiotics. The resistance phenotype starts with β-lactam antibiotic acylation of the BlaR1 extracellular domain (BlaRS). The acylation activates the cytoplasmic protease domain through an obscure signal transduction mechanism. Here, we compare protein dynamics of apo versus antibiotic-acylated BlaRS using nuclear magnetic resonance. Our analyses reveal inter-residue interactions that relay acylation-induced perturbations within the antibiotic-binding site to the transmembrane helix regions near the membrane surface. These are the first insights into the process of signal transduction by BlaR1.
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Affiliation(s)
- Michael W Staude
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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19
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Tao Y, Ran X, Ren J, Qu X. Array-based sensing of proteins and bacteria by using multiple luminescent nanodots as fluorescent probes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:3667-3671. [PMID: 24840238 DOI: 10.1002/smll.201400661] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Indexed: 06/03/2023]
Abstract
Luminescent nanodots for protein sensing and discrimination of bacteria: Luminescent nanodots are applied as novel fluorescent probes in a sensing array. The sensing strategy uses graphene oxide (GO) for protein recognition, with displacement of fluorescent probes to generate the output. This sensing platform is a powerful tool to detect protein targets and discriminate bacteria.
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Affiliation(s)
- Yu Tao
- Laboratory of Chemical Biology, Division of Biological Inorganic Chemistry, State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Changchun, 130022, China; Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun, 130022, China
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20
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Blázquez B, Llarrull LI, Luque-Ortega JR, Alfonso C, Boggess B, Mobashery S. Regulation of the expression of the β-lactam antibiotic-resistance determinants in methicillin-resistant Staphylococcus aureus (MRSA). Biochemistry 2014; 53:1548-50. [PMID: 24564530 PMCID: PMC3971960 DOI: 10.1021/bi500074w] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
![]()
β-Lactam
antibiotics have faced obsolescence with the emergence
of methicillin-resistant Staphylococcus aureus (MRSA).
A complex set of events ensues upon exposure of MRSA to these antibiotics,
which culminates in proteolysis of BlaI or MecI, two gene repressors,
and results in the induction of resistance. We report studies on the
mechanism of binding of these gene repressors to the operator regions
by fluorescence anisotropy. Within the range of in vivo concentrations for BlaI and MecI, these proteins interact with their
regulatory elements in a reversible manner, as both a monomer and
a dimer.
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Affiliation(s)
- Blas Blázquez
- Department Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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21
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Che T, Bethel CR, Pusztai-Carey M, Bonomo RA, Carey PR. The different inhibition mechanisms of OXA-1 and OXA-24 β-lactamases are determined by the stability of active site carboxylated lysine. J Biol Chem 2014; 289:6152-64. [PMID: 24443569 DOI: 10.1074/jbc.m113.533562] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The catalytic efficiency of class D β-lactamases depends critically on an unusual carboxylated lysine as the general base residue for both the acylation and deacylation steps of the enzyme. Microbiological and biochemical studies on the class D β-lactamases OXA-1 and OXA-24 showed that the two enzymes behave differently when reacting with two 6-methylidene penems (penem 1 and penem 3): the penems are good inhibitors of OXA-1 but act more like substrates for OXA-24. UV difference and Raman spectroscopy revealed that the respective reaction mechanisms are different. The penems form an unusual intermediate, a 1,4-thiazepine derivative in OXA-1, and undergo deacylation followed by the decarboxylation of Lys-70, rendering OXA-1 inactive. This inactivation could not be reversed by the addition of 100 mM NaHCO3. In OXA-24, under mild conditions (enzyme:inhibitor = 1:4), only hydrolyzed products were detected, and the enzyme remained active. However, under harsh conditions (enzyme:inhibitor = 1:2000), OXA-24 was inhibited via decarboxylation of Lys-84; however, the enzyme could be reactivated by the addition of 100 mM NaHCO3. We conclude that OXA-24 not only decarboxylates with difficulty but also recarboxylates with ease; in contrast, OXA-1 decarboxylates easily but recarboxylates with difficulty. Structural analysis of the active site indicates that a crystallographic water molecule may play an important role in carboxylation in OXA-24 (an analogous water molecule is not found in OXA-1), supporting the suggestion that a water molecule in the active site of OXA-24 can lower the energy barrier for carboxylation significantly.
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Affiliation(s)
- Tao Che
- From the Departments of Biochemistry
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22
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Chancey ST, Zähner D, Stephens DS. Acquired inducible antimicrobial resistance in Gram-positive bacteria. Future Microbiol 2013; 7:959-78. [PMID: 22913355 DOI: 10.2217/fmb.12.63] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often 'silent' spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide-lincosamide-streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of β-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations.
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Affiliation(s)
- Scott T Chancey
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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23
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Abstract
Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many--and quite possibly all--bacteria, the peptidoglycan fragments are recovered and recycled. Although cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall-targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall-recycling inhibitors.
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Affiliation(s)
- Jarrod W Johnson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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24
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Che T, Bonomo RA, Shanmugam S, Bethel CR, Pusztai-Carey M, Buynak JD, Carey PR. Carboxylation and decarboxylation of active site Lys 84 controls the activity of OXA-24 β-lactamase of Acinetobacter baumannii: Raman crystallographic and solution evidence. J Am Chem Soc 2012; 134:11206-15. [PMID: 22702961 DOI: 10.1021/ja303168n] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The class D β-lactamases are characterized by the presence of a carboxylated lysine in the active site that participates in catalysis. Found in Acinetobacter baumannii, OXA-24 is a class D carbapenem hydrolyzing enzyme that exhibits resistance to most available β-lactamase inhibitors. In this study, the reaction between a 6-alkylidiene penam sulfone inhibitor, SA-1-204, in single crystals of OXA-24 is followed by Raman microscopy. Details of its reaction with SA-1-204 provide insight into the enzyme's mode of action and help define the mechanism of inhibition. When the crystal is maintained in HEPES buffer, the reaction is fast, shorter than the time scale of the Raman experiment. However, when the crystal holding solution contains 28% PEG 2000, the reaction is slower and can be recorded by Raman microscopy in real time; the inhibitor's Raman bands quickly disappear, transient features are seen due to an early intermediate, and, at approximately 2-11 min, new bands appear that are assigned to the late intermediate species. At about 50 min, bands due to all intermediates are replaced by Raman signals of the unreacted inhibitor. The new population remains unchanged indicating (i) that the OXA-24 is no longer active and (ii) that the decarboxylation of Lys84 occurred during the first reaction cycle. Using absorbance spectroscopy, a one-cycle reaction could be carried out in aqueous solution producing inactive OXA-24 as assayed by the chromogenic substrate nitrocefin. However, activity could be restored by reacting aqueous OXA-24 with a large excess of NaHCO(3), which recarboxylates Lys84. In contrast, the addition of NaHCO(3) was not successful in reactivating OXA-24 in the crystalline state; this is ascribed to the inability to create a concentration of NaHCO(3) in large excess over the OXA-24 that is present in the crystal. The finding that inhibitor compounds can inactivate a class D enzyme by promoting decarboxylation of an active site lysine suggests a novel function that could be exploited in inhibitor design.
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Affiliation(s)
- Tao Che
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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25
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Llarrull LI, Mobashery S. Dissection of events in the resistance to β-lactam antibiotics mediated by the protein BlaR1 from Staphylococcus aureus. Biochemistry 2012; 51:4642-9. [PMID: 22616850 DOI: 10.1021/bi300429p] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A heterologous expression system was used to evaluate activation of BlaR1, a sensor/signal transducer protein of Staphylococcus aureus with a central role in resistance to β-lactam antibiotics. In the absence of other S. aureus proteins that might respond to antibiotics and participate in signal transduction events, we documented that BlaR1 fragmentation is autolytic, that it occurs in the absence of antibiotics, and that BlaR1 directly degrades BlaI, the gene repressor of the system. Furthermore, we disclosed that this proteolytic activity is metal ion-dependent and that it is not modulated directly by acylation of the sensor domain by β-lactam antibiotics.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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26
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Buchman JS, Schneider KD, Lloyd AR, Pavlish SL, Leonard DA. Site-saturation mutagenesis of position V117 in OXA-1 β-lactamase: effect of side chain polarity on enzyme carboxylation and substrate turnover. Biochemistry 2012; 51:3143-50. [PMID: 22429123 DOI: 10.1021/bi201896k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Class D β-lactamases pose an emerging threat to the efficacy of β-lactam therapy for bacterial infections. Class D enzymes differ mechanistically from other β-lactamases by the presence of an active-site N-carboxylated lysine that serves as a general base to activate the serine nucleophile for attack. We have used site-saturation mutagenesis at position V117 in the class D β-lactamase OXA-1 to investigate how alterations in the environment around N-carboxylated K70 affect the ability of that modified residue to carry out its normal function. Minimum inhibitory concentration analysis of the 20 position 117 variants demonstrates a clear pattern of charge and polarity effects on the level of ampicillin resistance imparted on Escherichia coli (E. coli). Substitutions that introduce a negative charge (D, E) at position 117 reduce resistance to near background levels, while the positively charged K and R residues maintain the highest resistance levels of all mutants. Treatment of the acidic variants with the fluorescent penicillin BOCILLIN FL followed by SDS-PAGE shows that they are active for acylation by substrate but deacylation-deficient. We used a novel fluorescence anisotropy assay to show that the specific charge and hydrogen-bonding potential of the residue at position 117 affect CO(2) binding to K70, which in turn correlates to deacylation activity. These conclusions are discussed in light of the mechanisms proposed for both class D β-lactamases and BlaR β-lactam sensor proteins and suggest a reason for the preponderance of asparagine at the V117-homologous position in the sensors.
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Affiliation(s)
- Jennifer S Buchman
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, USA
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27
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Kumarasiri M, Llarrull LI, Borbulevych O, Fishovitz J, Lastochkin E, Baker BM, Mobashery S. An amino acid position at crossroads of evolution of protein function: antibiotic sensor domain of BlaR1 protein from Staphylococcus aureus versus clasS D β-lactamases. J Biol Chem 2012; 287:8232-41. [PMID: 22262858 DOI: 10.1074/jbc.m111.333179] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The integral membrane protein BlaR1 of Staphylococcus aureus senses the presence of β-lactam antibiotics in the milieu and transduces the information to its cytoplasmic side, where its activity unleashes the expression of a set of genes, including that for BlaR1 itself, which manifest the antibiotic-resistant phenotype. The x-ray structure of the sensor domain of this protein exhibits an uncanny similarity to those of the class D β-lactamases. The former is a membrane-bound receptor/sensor for the β-lactam antibiotics, devoid of catalytic competence for substrate turnover, whereas the latter are soluble periplasmic enzymes in gram-negative bacteria with avid ability for β-lactam turnover. The two are clearly related to each other from an evolutionary point of view. However, the high resolution x-ray structures for both by themselves do not reveal why one is a receptor and the other an enzyme. It is documented herein that a single amino acid change at position 439 of the BlaR1 protein is sufficient to endow the receptor/sensor protein with modest turnover ability for cephalosporins as substrates. The x-ray structure for this mutant protein and the dynamics simulations revealed how a hydrolytic water molecule may sequester itself in the antibiotic-binding site to enable hydrolysis of the acylated species. These studies document how the nature of the residue at position 439 is critical for the fate of the protein in imparting unique functions on the same molecular template, to result in one as a receptor and in another as a catalyst.
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Affiliation(s)
- Malika Kumarasiri
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Llarrull LI, Toth M, Champion MM, Mobashery S. Activation of BlaR1 protein of methicillin-resistant Staphylococcus aureus, its proteolytic processing, and recovery from induction of resistance. J Biol Chem 2011; 286:38148-38158. [PMID: 21896485 DOI: 10.1074/jbc.m111.288985] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The fates of BlaI, the gene repressor protein for the bla operon, BlaR1, the β-lactam sensor/signal transducer, and PC1 β-lactamase in four strains of Staphylococcus aureus upon exposure to four different β-lactam antibiotics were investigated as a function of time. The genes for the three proteins are encoded by the bla operon, the functions of which afford inducible resistance to β-lactam antibiotics in S. aureus. BlaR1 protein is expressed at low copy number. Acylation of the sensor domain of BlaR1 by β-lactam antibiotics initiates signal transduction to the cytoplasmic domain, a zinc protease, which is activated and degrades BlaI. This proteolytic degradation derepresses transcription of all three genes, resulting in inducible resistance. These processes take place within minutes of exposure to the antibiotics. The BlaR1 protein was shown to undergo fragmentation in three S. aureus strains within the time frame relevant for manifestation of resistance and was below the detection threshold in the fourth. Two specific sites of fragmentation were identified, one cytoplasmic and the other in the sensor domain. This is proposed as a means for turnover, a process required for recovery from induction of resistance in S. aureus in the absence of the antibiotic challenge. In S. aureus not exposed to β-lactam antibiotics (i.e. not acylated by antibiotic) the same fragmentation of BlaR1 is still observed, including the shedding of the sensor domain, an observation that leads to the conclusion that the sites of proteolysis might have evolved to predispose the protein to degradation within a set period of time.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Matthew M Champion
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556.
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Borbulevych O, Kumarasiri M, Wilson B, Llarrull LI, Lee M, Hesek D, Shi Q, Peng J, Baker BM, Mobashery S. Lysine Nzeta-decarboxylation switch and activation of the beta-lactam sensor domain of BlaR1 protein of methicillin-resistant Staphylococcus aureus. J Biol Chem 2011; 286:31466-72. [PMID: 21775440 DOI: 10.1074/jbc.m111.252189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The integral membrane protein BlaR1 of methicillin-resistant Staphylococcus aureus senses the presence of β-lactam antibiotics in the milieu and transduces the information to the cytoplasm, where the biochemical events that unleash induction of antibiotic resistance mechanisms take place. We report herein by two-dimensional and three-dimensional NMR experiments of the sensor domain of BlaR1 in solution and by determination of an x-ray structure for the apo protein that Lys-392 of the antibiotic-binding site is posttranslationally modified by N(ζ)-carboxylation. Additional crystallographic and NMR data reveal that on acylation of Ser-389 by antibiotics, Lys-392 experiences N(ζ)-decarboxylation. This unique process, termed the lysine N(ζ)-decarboxylation switch, arrests the sensor domain in the activated ("on") state, necessary for signal transduction and all the subsequent biochemical processes. We present structural information on how this receptor activation process takes place, imparting longevity to the antibiotic-receptor complex that is needed for the induction of the antibiotic-resistant phenotype in methicillin-resistant S. aureus.
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Affiliation(s)
- Oleg Borbulevych
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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30
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Three factors that modulate the activity of class D β-lactamases and interfere with the post-translational carboxylation of Lys70. Biochem J 2011; 432:495-504. [PMID: 21108605 DOI: 10.1042/bj20101122] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The activity of class D β-lactamases is dependent on Lys70 carboxylation in the active site. Structural, kinetic and affinity studies show that this post-translational modification can be affected by the presence of a poor substrate such as moxalactam but also by the V117T substitution. Val117 is a strictly conserved hydrophobic residue located in the active site. In addition, inhibition of class D β-lactamases by chloride ions is due to a competition between the side chain carboxylate of the modified Lys70 and chloride ions. Determination of the individual kinetic constants shows that the deacylation of the acyl-enzyme is the rate-limiting step for the wild-type OXA-10 β-lactamase.
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31
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Llarrull LI, Prorok M, Mobashery S. Binding of the gene repressor BlaI to the bla operon in methicillin-resistant Staphylococcus aureus. Biochemistry 2010; 49:7975-7. [PMID: 20722402 DOI: 10.1021/bi101177a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The expression of the gene products in many methicillin-resistant Staphylococcus aureus (MRSA) strains is regulated by the gene repressor BlaI. Here we show that BlaI is a mixture of monomer and dimer at in vivo concentrations, binds to the operator regions preferentially as a monomeric protein, and the measured dissociation constants and in vivo concentrations account for the basal level transcription of the resistance genes. These observations for the first time provide a quantitative picture of the processes that take place in the cytoplasm that lead to the induction of antibiotic resistance factors to counter the challenge by β-lactams.
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Affiliation(s)
- Leticia I Llarrull
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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32
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Bou G, Santillana E, Sheri A, Beceiro A, Sampson J, Kalp M, Bethel CR, Distler AM, Drawz SM, Pagadala SRR, van den Akker F, Bonomo RA, Romero A, Buynak JD. Design, synthesis, and crystal structures of 6-alkylidene-2'-substituted penicillanic acid sulfones as potent inhibitors of Acinetobacter baumannii OXA-24 carbapenemase. J Am Chem Soc 2010; 132:13320-31. [PMID: 20822105 PMCID: PMC3393087 DOI: 10.1021/ja104092z] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Class D β-lactamases represent a growing and diverse class of penicillin-inactivating enzymes that are usually resistant to commercial β-lactamase inhibitors. As many such enzymes are found in multi-drug resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa, novel β-lactamase inhibitors are urgently needed. Five unique 6-alkylidene-2'-substituted penicillanic acid sulfones (1-5) were synthesized and tested against OXA-24, a clinically important β-lactamase that inactivates carbapenems and is found in A. baumannii. Based upon the roles Tyr112 and Met223 play in the OXA-24 β-lactamase, we also engineered two variants (Tyr112Ala and Tyr112Ala,Met223Ala) to test the hypothesis that the hydrophobic tunnel formed by these residues influences inhibitor recognition. IC(50) values against OXA-24 and two OXA-24 β-lactamase variants ranged from 10 ± 1 (4 vs WT) to 338 ± 20 nM (5 vs Tyr112Ala, Met223Ala). Compound 4 possessed the lowest K(i) (500 ± 80 nM vs WT), and 1 possessed the highest inactivation efficiency (k(inact)/K(i) = 0.21 ± 0.02 μM(-1) s(-1)). Electrospray ionization mass spectrometry revealed a single covalent adduct, suggesting the formation of an acyl-enzyme intermediate. X-ray structures of OXA-24 complexed to four inhibitors (2.0-2.6 Å) reveal the formation of stable bicyclic aromatic intermediates with their carbonyl oxygen in the oxyanion hole. These data provide the first structural evidence that 6-alkylidene-2'-substituted penicillin sulfones are effective mechanism-based inactivators of class D β-lactamases. Their unique chemistry makes them developmental candidates. Mechanisms for class D hydrolysis and inhibition are discussed, and a pathway for the evolution of the BlaR1 sensor of Staphylococcus aureus to the class D β-lactamases is proposed.
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Affiliation(s)
| | | | | | | | - Jared Sampson
- Departments of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Matthew Kalp
- Departments of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH
| | | | - Anne M. Distler
- Department of Pharmacology, Case Western Reserve University School of Medicine
| | - Sarah M. Drawz
- Department of Pathology, Case Western Reserve University School of Medicine
| | | | - Focco van den Akker
- Departments of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Robert A. Bonomo
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH
- Department of Pharmacology, Case Western Reserve University School of Medicine
- Department of Molecular Biology and Microbiology, Case Western Reserve University
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, 423 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, USA
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Schneider KD, Karpen ME, Bonomo RA, Leonard DA, Powers RA. The 1.4 A crystal structure of the class D beta-lactamase OXA-1 complexed with doripenem. Biochemistry 2010; 48:11840-7. [PMID: 19919101 DOI: 10.1021/bi901690r] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The clinical efficacy of carbapenem antibiotics depends on their resistance to the hydrolytic action of beta-lactamase enzymes. The structure of the class D beta-lactamase OXA-1 as an acyl complex with the carbapenem doripenem was determined to 1.4 A resolution. Unlike most class A and class C carbapenem complexes, the acyl carbonyl oxygen in the OXA-1-doripenem complex is bound in the oxyanion hole. Interestingly, no water molecules were observed in the vicinity of the acyl linkage, providing an explanation for why carbapenems inhibit OXA-1. The side chain amine of K70 remains fully carboxylated in the acyl structure, and the resulting carbamate group forms a hydrogen bond to the alcohol of the 6alpha-hydroxyethyl moiety of doripenem. The carboxylate attached to the beta-lactam ring of doripenem is stabilized by a salt bridge to K212 and a hydrogen bond with T213, in lieu of the interaction with an arginine side chain found in most other beta-lactamase-beta-lactam complexes (e.g., R244 in the class A member TEM-1). This novel set of interactions with the carboxylate results in a major shift of the carbapenem's pyrroline ring compared to the structure of the same ring in meropenem bound to OXA-13. Additionally, bond angles of the pyrroline ring suggest that after acylation, doripenem adopts the Delta(1) tautomer. These findings provide important insights into the role that carbapenems may have in the inactivation process of class D beta-lactamases.
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Affiliation(s)
- Kyle D Schneider
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, USA
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McCallum N, Berger-Bächi B, Senn MM. Regulation of antibiotic resistance in Staphylococcus aureus. Int J Med Microbiol 2009; 300:118-29. [PMID: 19800843 DOI: 10.1016/j.ijmm.2009.08.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Staphylococcus aureus has a formidable ability to adapt to varying environmental conditions and an extraordinary capacity to rapidly become resistant to virtually all antibiotics. Resistance develops either through mutations and rearrangements within the staphylococcal genome, or by the acquisition of resistance determinants. Antibiotic resistances often impose a fitness burden on the host. Such biological costs can be reduced by tight regulation and antibiotic-inducible expression of resistance genes, or by compensatory mutations. Resistance induction by antibiotics can be mediated by dedicated, antibiotic-recognizing signal transducers or by mechanisms relieving translational attenuation. Antibiotic tolerance and the expression of resistance phenotypes can also be strongly influenced by the genetic backgrounds of strains and several other factors. Modification and indirect regulation of resistance levels can occur by mutations that alter gene expression or substrate specificity of genes contributing to resistance. Insertion elements can alter resistance profiles by turning relevant genes on or off. Environmental conditions and stress response mechanisms triggered by perturbation of the cell envelope, DNA damage, or faulty intermediary metabolism can also have an impact on resistance development and expression. Clinically relevant resistance is often built up through multiple steps, each of which contributes to an increase in resistance. The driving force behind resistance formation is antibiotic stress, and under clinical conditions selection for resistance is continuously competing with selection for bacterial fitness.
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Affiliation(s)
- Nadine McCallum
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 32, CH-8006 Zürich, Switzerland
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Schneider KD, Bethel CR, Distler AM, Hujer AM, Bonomo RA, Leonard DA. Mutation of the active site carboxy-lysine (K70) of OXA-1 beta-lactamase results in a deacylation-deficient enzyme. Biochemistry 2009; 48:6136-45. [PMID: 19485421 DOI: 10.1021/bi900448u] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Class D beta-lactamases hydrolyze beta-lactam antibiotics by using an active site serine nucleophile to form a covalent acyl-enzyme intermediate and subsequently employ water to deacylate the beta-lactam and release product. Class D beta-lactamases are carboxylated on the epsilon-amino group of an active site lysine, with the resulting carbamate functional group serving as a general base. We discovered that substitutions of the active site serine and lysine in OXA-1 beta-lactamase, a monomeric class D enzyme, significantly disrupt catalytic turnover. Substitution of glycine for the nucleophilic serine (S67G) results in an enzyme that can still bind substrate but is unable to form a covalent acyl-enzyme intermediate. Substitution of the carboxylated lysine (K70), on the other hand, results in enzyme that can be acylated by substrate but is impaired with respect to deacylation. We employed the fluorescent penicillin BOCILLIN FL to show that three different substitutions for K70 (alanine, aspartate, and glutamate) lead to the accumulation of significant acyl-enzyme intermediate. Interestingly, BOCILLIN FL deacylation rates (t(1/2)) vary depending on the identity of the substituting residue, from approximately 60 min for K70A to undetectable deacylation for K70D. Tryptophan fluorescence spectroscopy was used to confirm that these results are applicable to natural (i.e., nonfluorescent) substrates. Deacylation by K70A, but not K70D or K70E, can be partially restored by the addition of short-chain carboxylic acid mimetics of the lysine carbamate. In conclusion, we establish the functional role of the carboxylated lysine in OXA-1 and highlight its specific role in acylation and deacylation.
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Affiliation(s)
- Kyle D Schneider
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, USA
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37
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Molecular basis and phenotype of methicillin resistance in Staphylococcus aureus and insights into new beta-lactams that meet the challenge. Antimicrob Agents Chemother 2009; 53:4051-63. [PMID: 19470504 DOI: 10.1128/aac.00084-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Klitgaard JK, Skov MN, Kallipolitis BH, Kolmos HJ. Reversal of methicillin resistance in Staphylococcus aureus by thioridazine. J Antimicrob Chemother 2008; 62:1215-21. [PMID: 18836185 DOI: 10.1093/jac/dkn417] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Thioridazine has been shown to reverse oxacillin resistance in methicillin-resistant Staphylococcus aureus (MRSA) in vitro. The aim of this study was to investigate whether thioridazine alone or in combination with oxacillin affects the transcription of the methicillin resistance gene mecA and the protein level of the encoded protein PBP2a. METHODS Viability of MRSA was determined in liquid media in the presence of oxacillin or thioridazine alone or in combination. Transcription of mecA was analysed by primer extension, and the protein level of PBP2a was analysed by western blotting in the presence of thioridazine and oxacillin. RESULTS We observed an increased susceptibility of MRSA towards oxacillin in the presence of thioridazine compared with bacteria grown with oxacillin or thioridazine alone. Transcription of mecA was reduced with increasing concentrations of thioridazine in the presence of a fixed amount of oxacillin. Furthermore, the protein level of PBP2a was reduced when bacteria were treated with the combination of oxacillin and thioridazine. The two drugs also affected the mRNA level of the beta-lactamase gene, blaZ. CONCLUSIONS The present study indicates that reversal of methicillin resistance by thioridazine in MRSA may be explained by a reduced transcription of mecA and blaZ, resulting in a reduced protein level of PBP2a.
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Affiliation(s)
- Janne K Klitgaard
- Department of Clinical Microbiology, Institute of Clinical Research, University of Southern Denmark, Odense University Hospital, Odense, Denmark.
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The role of OXA-1 beta-lactamase Asp(66) in the stabilization of the active-site carbamate group and in substrate turnover. Biochem J 2008; 410:455-62. [PMID: 18031291 DOI: 10.1042/bj20070573] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The OXA-1 beta-lactamase is one of the few class D enzymes that has an aspartate residue at position 66, a position that is proximal to the active-site residue Ser(67). In class A beta-lactamases, such as TEM-1 and SHV-1, residues adjacent to the active-site serine residue play a crucial role in inhibitor resistance and substrate selectivity. To probe the role of Asp(66) in substrate affinity and catalysis, we performed site-saturation mutagenesis at this position. Ampicillin MIC (minimum inhibitory concentration) values for the full set of Asp(66) mutants expressed in Escherichia coli DH10B ranged from < or =8 microg/ml for cysteine, proline and the basic amino acids to > or =256 microg/ml for asparagine, leucine and the wild-type aspartate. Replacement of aspartic acid by asparagine at position 66 also led to a moderate enhancement of extended-spectrum cephalosporin resistance. OXA-1 shares with other class D enzymes a carboxylated residue, Lys(70), that acts as a general base in the catalytic mechanism. The addition of 25 mM bicarbonate to Luria-Bertani-broth agar resulted in a > or =16-fold increase in MICs for most OXA-1 variants with amino acid replacements at position 66 when expressed in E. coli. Because Asp(66) forms hydrogen bonds with several other residues in the OXA-1 active site, we propose that this residue plays a role in stabilizing the CO2 bound to Lys(70) and thereby profoundly affects substrate turnover.
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40
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Jordan S, Hutchings MI, Mascher T. Cell envelope stress response in Gram-positive bacteria. FEMS Microbiol Rev 2008; 32:107-46. [PMID: 18173394 DOI: 10.1111/j.1574-6976.2007.00091.x] [Citation(s) in RCA: 268] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Sina Jordan
- Department of General Microbiology, Georg-August-University, Grisebachstrasse 8, Göttingen, Germany
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Cha J, Mobashery S. Lysine N(zeta)-decarboxylation in the BlaR1 protein from Staphylococcus aureus at the root of its function as an antibiotic sensor. J Am Chem Soc 2007; 129:3834-5. [PMID: 17343387 DOI: 10.1021/ja070472e] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jooyoung Cha
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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