1
|
Ding L, Sun Y, Zhang Y, Shen S, Hu F. In Vivo Development of Aztreonam Resistance in Meropenem-Resistant Pseudomonas aeruginosa Owing to Overexpression of the blaPDC-16. Microbiol Spectr 2023; 11:e0308022. [PMID: 37070974 PMCID: PMC10269455 DOI: 10.1128/spectrum.03080-22] [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: 08/06/2022] [Accepted: 03/30/2023] [Indexed: 04/19/2023] Open
Abstract
The rapid acquisition of antibiotic resistance of Pseudomonas aeruginosa has been a complex problem in clinics. Two meropenem-resistant P. aeruginosa isolates were collected from the same patient on May 24, 2021, and June 4, 2021, respectively. The first was susceptible to aztreonam, while the second displayed resistance. This study aimed to identify the genetic differences between two P. aeruginosa isolates and uncover alterations formed by the within-host bacterial evolution leading to aztreonam resistance during therapy. Strains were subjected to antimicrobial susceptibility testing using the broth microdilution method. Genomic DNAs were obtained to identify their genetic differences. The relative mRNA levels of β-lactam-resistance genes were determined by real-time PCR. Both isolates belonged to ST 773 high-risk clones with the same antibiotic resistance genes, eliminating the possibility of horizontally obtaining resistance genes. Reverse transcription (RT)-PCR results showed that the blaPDC-16 mRNA level in the second one was about 1,500 times higher than that in the first one. When 3-aminophenyl boronic acid was added, the second strain recovered its susceptibility to aztreonam, which confirmed that the overexpression of blaPDC-16 was the main reason for the isolate's resistance to aztreonam. Compared to the first strain, the second showed a single amino acid substitution in AmpR located upstream of blaPDC-16, which may contribute to the upregulation of blaPDC-16 and lead to aztreonam resistance. AmpR plays an essential role in regulating antibiotic resistance in P. aeruginosa, and there is a need to be alert to clinical treatment failures associated with mutations in ampR. IMPORTANCE Pseudomonas aeruginosa is notorious for being highly resistant to antimicrobial agents. In this study, two P. aeruginosa strains isolated from the same patient with different susceptibility to aztreonam were used to illustrate the within-host resistance evolution process of P. aeruginosa. Both isolates, which belonged to a ST773 high-risk clone, had the same β-lactam resistance genes (blaPDC-16, blaIMP-45, blaOXA-1, and blaOXA-395), which means the second isolate might have been derived from the first isolate by gaining aztreonam resistance via mutations associated with aztreonam resistance relative genes. Subsequently, we found that mutation in ampR may be the cause of aztreonam resistance in the second isolate. Mutation in ampR leads to its loss of control over blaPDC-16, allowing overexpression of blaPDC-16 and further resistance to aztreonam. This study revealed that ampR plays an essential role in regulating antibiotic resistance in P. aeruginosa. There is a need to be alert to clinical treatment failures associated with mutations in ampR.
Collapse
Affiliation(s)
- Li Ding
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China
| | - Yue Sun
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China
| | - Yizhuo Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China
| | - Siquan Shen
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China
| | - Fupin Hu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China
| |
Collapse
|
2
|
Zhai X, Wu G, Tao X, Yang S, Lv L, Zhu Y, Dong D, Xiang H. Success stories of natural product-derived compounds from plants as multidrug resistance modulators in microorganisms. RSC Adv 2023; 13:7798-7817. [PMID: 36909750 PMCID: PMC9994607 DOI: 10.1039/d3ra00184a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/01/2023] [Indexed: 03/14/2023] Open
Abstract
Microorganisms evolve resistance to antibiotics as a function of evolution. Antibiotics have accelerated bacterial resistance through mutations and acquired resistance through a combination of factors. In some cases, multiple antibiotic-resistant determinants are encoded in these genes, immediately making the recipient organism a "superbug". Current antimicrobials are no longer effective against infections caused by pathogens that have developed antimicrobial resistance (AMR), and the problem has become a crisis. Microorganisms that acquire resistance to chemotherapy (multidrug resistance) are a major obstacle for successful treatments. Pharmaceutical industries should be highly interested in natural product-derived compounds, as they offer new sources of chemical entities for the development of new drugs. Phytochemical research and recent experimental advances are discussed in this review in relation to the antimicrobial efficacy of selected natural product-derived compounds as well as details of synergistic mechanisms and structures. The present review recognizesand amplifies the importance of compounds with natural origins, which can be used to create safer and more effective antimicrobial drugs by combating microorganisms that are resistant to multiple types of drugs.
Collapse
Affiliation(s)
- Xiaohan Zhai
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Guoyu Wu
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Xufeng Tao
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Shilei Yang
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Linlin Lv
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Yanna Zhu
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Deshi Dong
- Department of Pharmacy, First Affiliated Hospital of Dalian Medical University Dalian China
| | - Hong Xiang
- Laboratory of Integrative Medicine, First Affiliated Hospital of Dalian Medical University Dalian China
| |
Collapse
|
3
|
Vacariu CM, Tanner ME. Recent Advances in the Synthesis and Biological Applications of Peptidoglycan Fragments. Chemistry 2022; 28:e202200788. [PMID: 35560956 DOI: 10.1002/chem.202200788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Indexed: 11/09/2022]
Abstract
The biosynthesis, breakdown, and modification of peptidoglycan (PG) play vital roles in both bacterial viability and in the response of human physiology to bacterial infection. Studies on PG biochemistry are hampered by the fact that PG is an inhomogeneous insoluble macromolecule. Chemical synthesis is therefore an important means to obtain PG fragments that may serve as enzyme substrates and elicitors of the human immune response. This review outlines the recent advances in the synthesis and biochemical studies of PG fragments, PG biosynthetic intermediates (such as Park's nucleotides and PG lipids), and PG breakdown products (such as muramyl dipeptides and anhydro-muramic acid-containing fragments). A rich variety of synthetic approaches has been applied to preparing such compounds since carbohydrate, peptide, and phospholipid chemical methodologies must all be applied.
Collapse
Affiliation(s)
- Condurache M Vacariu
- Department of Chemistry, University of British Columbia, V6T 1Z1, Vancouver, British Columbia, Canada
| | - Martin E Tanner
- Department of Chemistry, University of British Columbia, V6T 1Z1, Vancouver, British Columbia, Canada
| |
Collapse
|
4
|
Express Yourself: Quantitative Real-Time PCR Assays for Rapid Chromosomal Antimicrobial Resistance Detection in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2022; 66:e0020422. [PMID: 35467369 DOI: 10.1128/aac.00204-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The rise of antimicrobial-resistant (AMR) bacteria is a global health emergency. One critical facet of tackling this epidemic is more rapid AMR diagnosis in serious multidrug-resistant pathogens like Pseudomonas aeruginosa. Here, we designed and then validated two multiplex quantitative real-time PCR (qPCR) assays to simultaneously detect differential expression of the resistance-nodulation-division efflux pumps MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY-OprM, the AmpC β-lactamase, and the porin OprD, which are commonly associated with chromosomally encoded AMR. Next, qPCRs were tested on 15 sputa from 11 participants with P. aeruginosa respiratory infections to determine AMR profiles in vivo. We confirmed multiplex qPCR testing feasibility directly on sputa, representing a key advancement in in vivo AMR diagnosis. Notably, comparison of sputa with their derived isolates grown in Luria-Bertani broth (±2.5% NaCl) or a 5-antibiotic cocktail showed marked expression differences, illustrating the difficulty in replicating in vivo expression profiles in vitro. Cystic fibrosis sputa showed significantly reduced mexE and mexY expression compared with chronic obstructive pulmonary disease sputa, despite harboring fluoroquinolone- and aminoglycoside-resistant strains, indicating that these loci do not contribute to AMR in vivo. oprD was also significantly downregulated in cystic fibrosis sputa, even in the absence of contemporaneous carbapenem use, suggesting a common adaptive trait in chronic infections that may affect carbapenem efficacy. Sputum ampC expression was highest in participants receiving carbapenems (6.7 to 15×), some of whom were simultaneously receiving cephalosporins, the latter of which would be rendered ineffective by the upregulated ampC. Our qPCR assays provide valuable insights into the P. aeruginosa resistome, and their use on clinical specimens will permit timely treatment alterations that will improve patient outcomes and antimicrobial stewardship measures.
Collapse
|
5
|
Horizontal-Acquisition of a Promiscuous Peptidoglycan-Recycling Enzyme Enables Aphids To Influence Symbiont Cell Wall Metabolism. mBio 2021; 12:e0263621. [PMID: 34933456 PMCID: PMC8689515 DOI: 10.1128/mbio.02636-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
During evolution, enzymes can undergo shifts in preferred substrates or in catalytic activities. An intriguing question is how enzyme function changes following horizontal gene transfer, especially for bacterial genes that have moved to animal genomes. Some insects have acquired genes that encode enzymes for the biosynthesis of bacterial cell wall components and that appear to function to support or control their obligate endosymbiotic bacteria. In aphids, the bacterial endosymbiont Buchnera aphidicola provides essential amino acids for aphid hosts but lacks most genes for remodeling of the bacterial cell wall. The aphid genome has acquired seven genes with putative functions in cell wall metabolism that are primarily expressed in the aphid cells harboring Buchnera. In analyses of aphid homogenates, we detected peptidoglycan (PGN) muropeptides indicative of the reactions of PGN hydrolases encoded by horizontally acquired aphid genes but not by Buchnera genes. We produced one such host enzyme, ApLdcA, and characterized its activity with both cell wall derived and synthetic PGN. Both ApLdcA and the homologous enzyme in Escherichia coli, which functions as an l,d-carboxypeptidase in the cytoplasmic PGN recycling pathway, exhibit turnover of PGN substrates containing stem pentapeptides and cross-linkages via l,d-endopeptidase activity, consistent with a potential role in cell wall remodeling. Our results suggest that ApLdcA derives its functions from the promiscuous activities of an ancestral LdcA enzyme, whose acquisition by the aphid genome may have enabled hosts to influence Buchnera cell wall metabolism as a means to control symbiont growth and division. IMPORTANCE Most enzymes are capable of performing biologically irrelevant side reactions. During evolution, promiscuous enzyme activities may acquire new biological roles, especially after horizontal gene transfer to new organisms. Pea aphids harbor obligate bacterial symbionts called Buchnera and encode horizontally acquired bacterial genes with putative roles in cell wall metabolism. Though Buchnera lacks cell wall endopeptidase genes, we found evidence of endopeptidase activity among peptidoglycan muropeptides purified from aphids. We characterized a multifunctional, aphid-encoded enzyme, ApLdcA, which displays l,d-endopeptidase activities considered promiscuous for the Escherichia coli homolog, for which these activities do not contribute to its native role in peptidoglycan recycling. These results exemplify the roles of enzyme promiscuity and horizontal gene transfer in enzyme evolution and demonstrate how aphids influence symbiont cell wall metabolism.
Collapse
|
6
|
β-lactam Resistance in Pseudomonas aeruginosa: Current Status, Future Prospects. Pathogens 2021; 10:pathogens10121638. [PMID: 34959593 PMCID: PMC8706265 DOI: 10.3390/pathogens10121638] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa is a major opportunistic pathogen, causing a wide range of acute and chronic infections. β-lactam antibiotics including penicillins, carbapenems, monobactams, and cephalosporins play a key role in the treatment of P. aeruginosa infections. However, a significant number of isolates of these bacteria are resistant to β-lactams, complicating treatment of infections and leading to worse outcomes for patients. In this review, we summarize studies demonstrating the health and economic impacts associated with β-lactam-resistant P. aeruginosa. We then describe how β-lactams bind to and inhibit P. aeruginosa penicillin-binding proteins that are required for synthesis and remodelling of peptidoglycan. Resistance to β-lactams is multifactorial and can involve changes to a key target protein, penicillin-binding protein 3, that is essential for cell division; reduced uptake or increased efflux of β-lactams; degradation of β-lactam antibiotics by increased expression or altered substrate specificity of an AmpC β-lactamase, or by the acquisition of β-lactamases through horizontal gene transfer; and changes to biofilm formation and metabolism. The current understanding of these mechanisms is discussed. Lastly, important knowledge gaps are identified, and possible strategies for enhancing the effectiveness of β-lactam antibiotics in treating P. aeruginosa infections are considered.
Collapse
|
7
|
Li Y, Xia L, Chen J, Lian Y, Dandekar AA, Xu F, Wang M. Resistance elicited by sub-lethal concentrations of ampicillin is partially mediated by quorum sensing in Pseudomonas aeruginosa. ENVIRONMENT INTERNATIONAL 2021; 156:106619. [PMID: 33989839 DOI: 10.1016/j.envint.2021.106619] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
The rapid increase of antibiotic resistance is a serious challenge around the world. Antibiotics are present in various environments at sub-lethal concentrations, but how resistance emerges under sub-lethal conditions is not fully clear. In this study, we evolved Pseudomonas aeruginosa PAO1 under sub-lethal conditions, in the presence of either 15-30 μg/mL or 150-300 μg/mL of ampicillin. We found a ~ 5-6 fold increase in the minimum inhibitory concentration (MIC) among evolved isolates exposed to 15-30 μg/mL of ampicillin, and more than a 19-fold of increase in 150-300 μg/mL of ampicillin exposure. DNA sequencing revealed that mpl and ampD were frequently mutated in these resistant strains. We performed a transcriptome analysis of deletion mutations of mpl or ampD, compared to PAO1. Both showed a two-fold increase in expression of quorum sensing (QS) genes including lasR and rhlI/R; the heightened expression was positively correlated with the expression of the ampicillin resistance gene ampC. We queried if quorum sensing contributes to the increase in the ampicillin MIC. After adding the quorum quencher acylase I, the growth yield both decreased by roughly 50% for Δmpl in 2000 μg/mL of ampicillin and ΔampD in 4000 μg/mL of ampicillin. Addition of the QS signals into synthase mutants restored the higher MIC, but only for the rhlI/R circuit. This study highlights the involvement of QS in antibiotic resistance evolution, and shows the multifactorial contributors to the observed phenotypes.
Collapse
Affiliation(s)
- Yue Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Lexin Xia
- Department of Infectious Diseases, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Jian Chen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Yulu Lian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Ajai A Dandekar
- Department of Medicine, University of Washington, Seattle, WA 98195, USA; Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Feng Xu
- Department of Infectious Diseases, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China.
| |
Collapse
|
8
|
Sun H, Yu Y, Zhang Y, Li J, Cheng Y, Huang S, Wang W, Zhang X. Glycosylated Nanotherapeutics with β-Lactamase Reversible Competitive Inhibitory Activity Reinvigorates Antibiotics against Gram-Negative Bacteria. Biomacromolecules 2021; 22:2834-2849. [PMID: 34164980 DOI: 10.1021/acs.biomac.1c00231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antibiotics are currently first-line therapy for bacterial infections. However, the curative effect of antibiotic remedies is limited due to increasingly prevalent bacterial resistance. The strategy to reverse intrinsic acquired drug resistance presents a promising option for reinvigorating antibiotic therapy. Here, we developed a β-lactamase-inhibiting macromolecule composed of benzoxaborole and dextran for precise transport of β-lactam antibiotics to strains overexpressing β-lactamase. Benzoxaborole-derived nanotherapeutics enabled specific recognition and rapid internalization, and the nanotherapeutics with a high affinity toward bacteria distinctly inhibited the catalytic activity of bacterially secreted β-lactamase by a reversible competitive mechanism. Thus, the system entrapping cefoxitin harbored a significantly enhanced ability to kill drug-resistant Escherichia coli compared to the ability of the drug by specifically overcoming the membrane barrier and acquired resistance mechanism of β-lactamase overproduction. The reversible competitive nanotherapeutics exhibited a robust therapeutic efficacy in rat wounds infected with drug-resistant bacteria; the efficacy was due to efficient bacterial elimination and collateral benzoxaborole-dependent amelioration of the inflammatory response. The above results offered insights into the facile design of precise macromolecular adjuvants to exclusively reverse the acquired bacterial resistance mechanism and increase the utility of antibiotic therapies against antibiotic-resistant bacterial infections.
Collapse
Affiliation(s)
- Haonan Sun
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yunjian Yu
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yufei Zhang
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Jie Li
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yijie Cheng
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Siyuan Huang
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Wenbo Wang
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Xinge Zhang
- Key Laboratory of Functional Polymer Materials of Ministry Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| |
Collapse
|
9
|
Ebomah KE, Okoh AI. Detection of Carbapenem-Resistance Genes in Klebsiella Species Recovered from Selected Environmental Niches in the Eastern Cape Province, South Africa. Antibiotics (Basel) 2020; 9:E425. [PMID: 32708057 PMCID: PMC7400071 DOI: 10.3390/antibiotics9070425] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 02/02/2023] Open
Abstract
Carbapenemase-producing Enterobacteriaceae (CPE) have been heavily linked to hospital acquired infections (HAI) thereby leading to futility of antibiotics in treating infections and this have complicated public health problems. There is little knowledge about carbapenemase-producing Klebsiella spp. (CPK) in South Africa. This study aimed at determining the occurrence of CPK in different samples collected from selected environmental niches (hospitals, wastewater treatment plants, rivers, farms) in three district municipalities located in the Eastern Cape Province, South Africa. Molecular identification and characterization of the presumptive isolates were determined using polymerase chain reaction (PCR) and isolates that exhibited phenotypic carbapenem resistance were further screened for the possibility of harbouring antimicrobial resistance genes. One hundred (43%) of the 234 confirmed Klebsiella spp. isolates harboured carbapenem-resistance genes; 10 isolates harboured blaOXA-48-like; 17 harboured blaKPC; and 73 isolates harboured blaNDM-1. The emergence of blaKPC, blaOXA-48-like, and blaNDM-1 carbapenem-resistance genes in Klebsiella species associated with environmental sources is of great concern to public health.
Collapse
Affiliation(s)
- Kingsley Ehi Ebomah
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice 5700, South Africa
- Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, South Africa
| | - Anthony Ifeanyi Okoh
- SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice 5700, South Africa
- Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Alice 5700, South Africa
| |
Collapse
|
10
|
Hrichi H, Elkanzi NAA, Bakr RB. Novel Β-lactams and Thiazolidinone Derivatives from 1,4-dihydroquinoxaline Schiff’s Base: Synthesis, Antimicrobial Activity and Molecular Docking Studies. CHEMISTRY JOURNAL OF MOLDOVA 2020. [DOI: 10.19261/cjm.2019.647] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
11
|
Dik DA, Kim C, Madukoma CS, Fisher JF, Shrout JD, Mobashery S. Fluorescence Assessment of the AmpR-Signaling Network of Pseudomonas aeruginosa to Exposure to β-Lactam Antibiotics. ACS Chem Biol 2020; 15:1184-1194. [PMID: 31990176 DOI: 10.1021/acschembio.9b00875] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gram-negative bacteria have evolved an elaborate pathway to sense and respond to exposure to β-lactam antibiotics. The β-lactam antibiotics inhibit penicillin-binding proteins, whereby the loss of their activities alters/damages the cell-wall peptidoglycan. Bacteria sense this damage and remove the affected peptidoglycan into complex recycling pathways. As an offshoot of these pathways, muropeptide chemical signals generated from the cell-wall recycling manifest the production of a class C β-lactamase, which hydrolytically degrades the β-lactam antibiotic as a resistance mechanism. We disclose the use of a fluorescence probe that detects the activation of the recycling system by the formation of the key muropeptides involved in signaling. This same probe additionally detects natural-product cell-wall-active antibiotics that are produced in situ by cohabitating bacteria.
Collapse
Affiliation(s)
- David A. Dik
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Choon Kim
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Chinedu S. Madukoma
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Joshua D. Shrout
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| |
Collapse
|
12
|
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: 31] [Impact Index Per Article: 7.8] [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.
Collapse
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
| |
Collapse
|
13
|
Min K, An DR, Yoon HJ, Rana N, Park JS, Kim J, Lee M, Hesek D, Ryu S, Kim BM, Mobashery S, Suh SW, Lee HH. Peptidoglycan reshaping by a noncanonical peptidase for helical cell shape in Campylobacter jejuni. Nat Commun 2020; 11:458. [PMID: 31974386 PMCID: PMC6978369 DOI: 10.1038/s41467-019-13934-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 12/10/2019] [Indexed: 12/27/2022] Open
Abstract
Assembly of the peptidoglycan is crucial in maintaining viability of bacteria and in defining bacterial cell shapes, both of which are important for existence in the ecological niche that the organism occupies. Here, eight crystal structures for a member of the cell-shape-determining class of Campylobacter jejuni, the peptidoglycan peptidase 3 (Pgp3), are reported. Characterization of the turnover chemistry of Pgp3 reveals cell wall d,d-endopeptidase and d,d-carboxypeptidase activities. Catalysis is accompanied by large conformational changes upon peptidoglycan binding, whereby a loop regulates access to the active site. Furthermore, prior hydrolysis of the crosslinked peptide stem from the saccharide backbone of the peptidoglycan on one side is a pre-requisite for its recognition and turnover by Pgp3. These analyses reveal the noncanonical nature of the transformations at the core of the events that define the morphological shape for C. jejuni as an intestinal pathogen. Peptidoglycans (PG) define bacterial cell shapes. Here, the authors provide mechanistic insights into the peptidoglycan peptidase 3 (Pgp3) from the spiral shaped human pathogen Campylobacter jejuni by determining its crystal structure alone and in complex with synthetic cell-wall PG derivatives, and they further show that the enzyme has both d,d-endopeptidase and d,d-carboxypeptidase activities
Collapse
Affiliation(s)
- Kyungjin Min
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Doo Ri An
- Department of Biophysics and Chemical Biology, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea.,Hazardous Substances Analysis Division, Gyeongin Regional Office of Food and Drug Safety, Incheon, 22133, Korea
| | - Hye-Jin Yoon
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Neha Rana
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, IN, 46556, USA
| | - Ji Su Park
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Jinshil Kim
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Korea
| | - Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, IN, 46556, USA
| | - Dusan Hesek
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, IN, 46556, USA
| | - Sangryeol Ryu
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Korea.,Center for Food and Bioconvergence, Seoul National University, Seoul, 08826, Korea
| | - B Moon Kim
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, IN, 46556, USA.
| | - Se Won Suh
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea. .,Department of Biophysics and Chemical Biology, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea.
| | - Hyung Ho Lee
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul, 08826, Korea.
| |
Collapse
|
14
|
Regulation of AmpC-Driven β-Lactam Resistance in Pseudomonas aeruginosa: Different Pathways, Different Signaling. mSystems 2019; 4:4/6/e00524-19. [PMID: 31796566 PMCID: PMC6890930 DOI: 10.1128/msystems.00524-19] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The extensive use of β-lactam antibiotics and the bacterial adaptive capacity have led to the apparently unstoppable increase of antimicrobial resistance, one of the current major global health challenges. In the leading nosocomial pathogen Pseudomonas aeruginosa, the mutation-driven AmpC β-lactamase hyperproduction stands out as the main resistance mechanism, but the molecular cues enabling this system have remained elusive until now. Here, we provide for the first time direct and quantitative information about the soluble cell wall-derived fragments accounting for the different levels and pathways of AmpC hyperproduction. Based on these results, we propose a hierarchical model of signals which ultimately govern ampC hyperexpression and resistance. The hyperproduction of the chromosomal AmpC β-lactamase is the main mechanism driving β-lactam resistance in Pseudomonas aeruginosa, one of the leading opportunistic pathogens causing nosocomial acute and chronic infections in patients with underlying respiratory diseases. In the current scenario of the shortage of effective antipseudomonal drugs, understanding the molecular mechanisms mediating AmpC hyperproduction in order to develop new therapeutics against this fearsome pathogen is of great importance. It has been accepted for decades that certain cell wall-derived soluble fragments (muropeptides) modulate AmpC production by complexing with the transcriptional regulator AmpR and acquiring different conformations that activate/repress ampC expression. However, these peptidoglycan-derived signals have never been characterized in the highly prevalent P. aeruginosa stable AmpC hyperproducer mutants. Here, we demonstrate that the previously described fragments enabling the transient ampC hyperexpression during cefoxitin induction (1,6-anhydro-N-acetylmuramyl-pentapeptides) also underlie the dacB (penicillin binding protein 4 [PBP4]) mutation-driven stable hyperproduction but differ from the 1,6-anhydro-N-acetylmuramyl-tripeptides notably overaccumulated in the ampD knockout mutant. In addition, a simultaneous greater accumulation of both activators appears linked to higher levels of AmpC hyperproduction, although our results suggest a much stronger AmpC-activating potency for the 1,6-anhydro-N-acetylmuramyl-pentapeptide. Collectively, our results propose a model of AmpC control where the activator fragments, with qualitative and quantitative particularities depending on the pathways and levels of β-lactamase production, dominate over the repressor (UDP-N-acetylmuramyl-pentapeptide). This study represents a major step in understanding the foundations of AmpC-dependent β-lactam resistance in P. aeruginosa, potentially useful to open new therapeutic conceptions intended to interfere with the abovementioned cell wall-derived signaling. IMPORTANCE The extensive use of β-lactam antibiotics and the bacterial adaptive capacity have led to the apparently unstoppable increase of antimicrobial resistance, one of the current major global health challenges. In the leading nosocomial pathogen Pseudomonas aeruginosa, the mutation-driven AmpC β-lactamase hyperproduction stands out as the main resistance mechanism, but the molecular cues enabling this system have remained elusive until now. Here, we provide for the first time direct and quantitative information about the soluble cell wall-derived fragments accounting for the different levels and pathways of AmpC hyperproduction. Based on these results, we propose a hierarchical model of signals which ultimately govern ampC hyperexpression and resistance.
Collapse
|
15
|
Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
Collapse
Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - 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
| |
Collapse
|
16
|
Abstract
During the past century, β-lactams have been identified as the core of penicillin and since then several strategies have been developed for their synthesis.
Collapse
|
17
|
Dhar S, Kumari H, Balasubramanian D, Mathee K. Cell-wall recycling and synthesis in Escherichia coli and Pseudomonas aeruginosa – their role in the development of resistance. J Med Microbiol 2018; 67:1-21. [DOI: 10.1099/jmm.0.000636] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Supurna Dhar
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Hansi Kumari
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | | | - Kalai Mathee
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| |
Collapse
|
18
|
Scoffone VC, Chiarelli LR, Trespidi G, Mentasti M, Riccardi G, Buroni S. Burkholderia cenocepacia Infections in Cystic Fibrosis Patients: Drug Resistance and Therapeutic Approaches. Front Microbiol 2017; 8:1592. [PMID: 28878751 PMCID: PMC5572248 DOI: 10.3389/fmicb.2017.01592] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/04/2017] [Indexed: 12/29/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen particularly dangerous for cystic fibrosis (CF) patients. It can cause a severe decline in CF lung function possibly developing into a life-threatening systemic infection known as cepacia syndrome. Antibiotic resistance and presence of numerous virulence determinants in the genome make B. cenocepacia extremely difficult to treat. Better understanding of its resistance profiles and mechanisms is crucial to improve management of these infections. Here, we present the clinical distribution of B. cenocepacia described in the last 6 years and methods for identification and classification of epidemic strains. We also detail new antibiotics, clinical trials, and alternative approaches reported in the literature in the last 5 years to tackle B. cenocepacia resistance issue. All together these findings point out the urgent need of new and alternative therapies to improve CF patients’ life expectancy.
Collapse
Affiliation(s)
- Viola C Scoffone
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | | | - Gabriele Trespidi
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | - Massimo Mentasti
- Respiratory and Vaccine Preventable Bacteria Reference Unit, Public Health EnglandLondon, United Kingdom.,Department of Microbiology, Royal Cornwall HospitalTruro, United Kingdom
| | - Giovanna Riccardi
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | - Silvia Buroni
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| |
Collapse
|
19
|
Identification of MupP as a New Peptidoglycan Recycling Factor and Antibiotic Resistance Determinant in Pseudomonas aeruginosa. mBio 2017; 8:mBio.00102-17. [PMID: 28351916 PMCID: PMC5371409 DOI: 10.1128/mbio.00102-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Peptidoglycan (PG) is an essential cross-linked polymer that surrounds most bacterial cells to prevent osmotic rupture of the cytoplasmic membrane. Its synthesis relies on penicillin-binding proteins, the targets of beta-lactam antibiotics. Many Gram-negative bacteria, including the opportunistic pathogen Pseudomonas aeruginosa, are resistant to beta-lactams because of a chromosomally encoded beta-lactamase called AmpC. In P. aeruginosa, expression of the ampC gene is tightly regulated and its induction is linked to cell wall stress. We reasoned that a reporter gene fusion to the ampC promoter would allow us to identify mutants defective in maintaining cell wall homeostasis and thereby uncover new factors involved in the process. A library of transposon-mutagenized P. aeruginosa was therefore screened for mutants with elevated ampC promoter activity. As an indication that the screen was working as expected, mutants with transposons disrupting the dacB gene were isolated. Defects in DacB have previously been implicated in ampC induction and clinical resistance to beta-lactam antibiotics. The screen also uncovered murU and PA3172 mutants that, upon further characterization, displayed nearly identical drug resistance and sensitivity profiles. We present genetic evidence that PA3172, renamed mupP, encodes the missing phosphatase predicted to function in the MurU PG recycling pathway that is widely distributed among Gram-negative bacteria. The cell wall biogenesis pathway is the target of many of our best antibiotics, including penicillin and related beta-lactam drugs. Resistance to these therapies is on the rise, particularly among Gram-negative species like Pseudomonas aeruginosa, a problematic opportunistic pathogen. To better understand how these organisms resist cell wall-targeting antibiotics, we screened for P. aeruginosa mutants defective in maintaining cell wall homeostasis. The screen identified a new factor, called MupP, involved in the recycling of cell wall turnover products. Characterization of MupP and other components of the pathway revealed that cell wall recycling plays important roles in both the resistance and the sensitivity of P. aeruginosa to cell wall-targeting antibiotics.
Collapse
|
20
|
Hamou-Segarra M, Zamorano L, Vadlamani G, Chu M, Sanchez-Diener I, Juan C, Blazquez J, Hattie M, Stubbs KA, Mark BL, Oliver A. Synergistic activity of fosfomycin, β-lactams and peptidoglycan recycling inhibition againstPseudomonas aeruginosa. J Antimicrob Chemother 2016; 72:448-454. [DOI: 10.1093/jac/dkw456] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 01/26/2023] Open
|
21
|
Abstract
Understanding the interplay between antibiotic resistance and bacterial fitness and virulence is essential to guide individual treatments and improve global antibiotic policies. A paradigmatic example of a resistance mechanism is the intrinsic inducible chromosomal β-lactamase AmpC from multiple Gram-negative bacteria, including Pseudomonas aeruginosa, a major nosocomial pathogen. The regulation of ampC expression is intimately linked to peptidoglycan recycling, and AmpC-mediated β-lactam resistance is frequently mediated by inactivating mutations in ampD, encoding an N-acetyl-anhydromuramyl-l-alanine amidase, affecting the levels of ampC-activating muropeptides. Here we dissect the impact of the multiple pathways causing AmpC hyperproduction on P. aeruginosa fitness and virulence. Through a detailed analysis, we demonstrate that the lack of all three P. aeruginosa AmpD amidases causes a dramatic effect in fitness and pathogenicity, severely compromising growth rates, motility, and cytotoxicity; the latter effect is likely achieved by repressing key virulence factors, such as protease LasA, phospholipase C, or type III secretion system components. We also show that ampC overexpression is required but not sufficient to confer the growth-motility-cytotoxicity impaired phenotype and that alternative pathways leading to similar levels of ampC hyperexpression and resistance, such as those involving PBP4, had no fitness-virulence cost. Further analysis indicated that fitness-virulence impairment is caused by overexpressing ampC in the absence of cell wall recycling, as reproduced by expressing ampC from a plasmid in an AmpG (muropeptide permease)-deficient background. Thus, our findings represent a major step in the understanding of β-lactam resistance biology and its interplay with fitness and pathogenesis. IMPORTANCE Understanding the impact of antibiotic resistance mechanisms on bacterial pathogenesis is critical to curb the spread of antibiotic resistance. A particularly noteworthy antibiotic resistance mechanism is the β-lactamase AmpC, produced by Pseudomonas aeruginosa, a major pathogen causing hospital-acquired infections. The regulation of AmpC is linked to the cell wall recycling pathways, and frequently, resistance to β-lactams is caused by mutation of several of the components of the cell wall recycling pathways such as AmpD. Here we dissect the impact of the pathways for AmpC hyperproduction on virulence, showing that the lack of all three P. aeruginosa AmpD amidases causes a major effect in fitness and pathogenicity, compromising growth, motility, and cytotoxicity. Further analysis indicated that fitness-virulence impairment is specifically caused by the hyperproduction of AmpC in the absence of cell wall recycling. Our work provides valuable information for delineating future strategies for combating P. aeruginosa infections by simultaneously targeting virulence and antibiotic resistance.
Collapse
|
22
|
Aguilera Rossi CG, Gómez-Puertas P, Ayala Serrano JA. In vivo functional and molecular characterization of the Penicillin-Binding Protein 4 (DacB) of Pseudomonas aeruginosa. BMC Microbiol 2016; 16:234. [PMID: 27716106 PMCID: PMC5054556 DOI: 10.1186/s12866-016-0853-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/27/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Community and nosocomial infections by Pseudomonas aeruginosa still create a major therapeutic challenge. The resistance of this opportunist pathogen to β-lactam antibiotics is determined mainly by production of the inactivating enzyme AmpC, a class C cephalosporinase with a regulation system more complex than those found in members of the Enterobacteriaceae family. This regulatory system also participates directly in peptidoglycan turnover and recycling. One of the regulatory mechanisms for AmpC expression, recently identified in clinical isolates, is the inactivation of LMM-PBP4 (Low-Molecular-Mass Penicillin-Binding Protein 4), a protein whose catalytic activity on natural substrates has remained uncharacterized until now. RESULTS We carried out in vivo activity trials for LMM-PBP4 of Pseudomonas aeruginosa on macromolecular peptidoglycan of Escherichia coli and Pseudomonas aeruginosa. The results showed a decrease in the relative quantity of dimeric, trimeric and anhydrous units, and a smaller reduction in monomer disaccharide pentapeptide (M5) levels, validating the occurrence of D,D-carboxypeptidase and D,D-endopeptidase activities. Under conditions of induction for this protein and cefoxitin treatment, the reduction in M5 is not fully efficient, implying that LMM-PBP4 of Pseudomonas aeruginosa presents better behaviour as a D,D-endopeptidase. Kinetic evaluation of the direct D,D-peptidase activity of this protein on natural muropeptides M5 and D45 confirmed this bifunctionality and the greater affinity of LMM-PBP4 for its dimeric substrate. A three-dimensional model for the monomeric unit of LMM-PBP4 provided structural information which supports its catalytic performance. CONCLUSIONS LMM-PBP4 of Pseudomonas aeruginosa is a bifunctional enzyme presenting both D,D-carboxypeptidase and D,D-endopeptidase activities; the D,D-endopeptidase function is predominant. Our study provides unprecedented functional and structural information which supports the proposal of this protein as a potential hydrolase-autolysin associated with peptidoglycan maturation and recycling. The fact that mutant PBP4 induces AmpC, may indicate that a putative muropeptide-subunit product of the DD-EPase activity of PBP4 could be a negative regulator of the pathway. This data contributes to understanding of the regulatory aspects of resistance to β-lactam antibiotics in this bacterial model.
Collapse
Affiliation(s)
- Cristian Gustavo Aguilera Rossi
- Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad de La Frontera, Temuco, Chile.,Laboratorio de División Celular Bacteriana y Resistencia a Antibióticos, Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid-CSIC, Madrid, Spain
| | - Paulino Gómez-Puertas
- Grupo de Modelado Molecular, Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid-CSIC, Madrid, Spain
| | - Juan Alfonso Ayala Serrano
- Laboratorio de División Celular Bacteriana y Resistencia a Antibióticos, Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid-CSIC, Madrid, Spain.
| |
Collapse
|
23
|
Domínguez-Gil T, Molina R, Alcorlo M, Hermoso JA. Renew or die: The molecular mechanisms of peptidoglycan recycling and antibiotic resistance in Gram-negative pathogens. Drug Resist Updat 2016; 28:91-104. [PMID: 27620957 DOI: 10.1016/j.drup.2016.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antimicrobial resistance is one of the most serious health threats. Cell-wall remodeling processes are tightly regulated to warrant bacterial survival and in some cases are directly linked to antibiotic resistance. Remodeling produces cell-wall fragments that are recycled but can also act as messengers for bacterial communication, as effector molecules in immune response and as signaling molecules triggering antibiotic resistance. This review is intended to provide state-of-the-art information about the molecular mechanisms governing this process and gather structural information of the different macromolecular machineries involved in peptidoglycan recycling in Gram-negative bacteria. The growing body of literature on the 3D structures of the corresponding macromolecules reveals an extraordinary complexity. Considering the increasing incidence and widespread emergence of Gram-negative multidrug-resistant pathogens in clinics, structural information on the main actors of the recycling process paves the way for designing novel antibiotics disrupting cellular communication in the recycling-resistance pathway.
Collapse
Affiliation(s)
- Teresa Domínguez-Gil
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Rafael Molina
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Martín Alcorlo
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain.
| |
Collapse
|
24
|
Lee M, Dhar S, De Benedetti S, Hesek D, Boggess B, Blázquez B, Mathee K, Mobashery S. Muropeptides in
Pseudomonas aeruginosa
and their Role as Elicitors of β‐Lactam‐Antibiotic Resistance. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mijoon Lee
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| | - Supurna Dhar
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine Florida International University Miami FL 33199 USA
| | - Stefania De Benedetti
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| | - Dusan Hesek
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| | - Bill Boggess
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| | - Blas Blázquez
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| | - Kalai Mathee
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine Florida International University Miami FL 33199 USA
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry University of Notre Dame Notre Dame IN 46556 USA
| |
Collapse
|
25
|
Affiliation(s)
- R. F. Pratt
- Department
of Chemistry, Wesleyan University, Lawn Avenue, Middletown, Connecticut 06459, United States
| |
Collapse
|
26
|
Lee M, Dhar S, De Benedetti S, Hesek D, Boggess B, Blázquez B, Mathee K, Mobashery S. Muropeptides in Pseudomonas aeruginosa and their Role as Elicitors of β-Lactam-Antibiotic Resistance. Angew Chem Int Ed Engl 2016; 55:6882-6. [PMID: 27111486 DOI: 10.1002/anie.201601693] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/07/2016] [Indexed: 11/11/2022]
Abstract
Muropeptides are a group of bacterial natural products generated from the cell wall in the course of its turnover. These compounds are cell-wall recycling intermediates and are also involved in signaling within the bacterium. However, the identity of these signaling molecules remains elusive. The identification and characterization of 20 muropeptides from Pseudomonas aeruginosa is described. The least abundant of these metabolites is present at 100 and the most abundant at 55,000 molecules per bacterium. Analysis of these muropeptides under conditions of induction of resistance to a β-lactam antibiotic identified two signaling muropeptides (N-acetylglucosamine-1,6-anhydro-N-acetylmuramyl pentapeptide and 1,6-anhydro-N-acetylmuramyl pentapeptide). Authentic synthetic samples of these metabolites were shown to activate expression of β-lactamase in the absence of any β-lactam antibiotic, thus indicating that they serve as chemical signals in this complex biochemical pathway.
Collapse
Affiliation(s)
- Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Supurna Dhar
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA
| | - Stefania De Benedetti
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Dusan Hesek
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Bill Boggess
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Blas Blázquez
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Kalai Mathee
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA.
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA.
| |
Collapse
|
27
|
Cell Wall Recycling-Linked Coregulation of AmpC and PenB β-Lactamases through ampD Mutations in Burkholderia cenocepacia. Antimicrob Agents Chemother 2015; 59:7602-10. [PMID: 26416862 DOI: 10.1128/aac.01068-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 09/21/2015] [Indexed: 01/07/2023] Open
Abstract
In many Gram-negative pathogens, mutations in the key cell wall-recycling enzyme AmpD (N-acetyl-anhydromuramyl-L-alanine amidase) affect the activity of the regulator AmpR, which leads to the expression of AmpC β-lactamase, conferring resistance to expanded-spectrum cephalosporin antibiotics. Burkholderia cepacia complex (Bcc) species also have these Amp homologs; however, the regulatory circuitry and the nature of causal ampD mutations remain to be explored. A total of 92 ampD mutants were obtained, representing four types of mutations: single nucleotide substitution (causing an amino acid substitution or antitermination of the enzyme), duplication, deletion, and IS element insertion. Duplication, which can go through reversion, was the most frequent type. Intriguingly, mutations in ampD led to the induction of two β-lactamases, AmpC and PenB. Coregulation of AmpC and PenB in B. cenocepacia, and likely also in many Bcc species with the same gene organization, poses a serious threat to human health. This resistance mechanism is of evolutionary optimization in that ampD is highly prone to mutations allowing rapid response to antibiotic challenge, and many of the mutations are reversible in order to resume cell wall recycling when the antibiotic challenge is relieved.
Collapse
|
28
|
Lamers RP, Nguyen UT, Nguyen Y, Buensuceso RNC, Burrows LL. Loss of membrane-bound lytic transglycosylases increases outer membrane permeability and β-lactam sensitivity in Pseudomonas aeruginosa. Microbiologyopen 2015; 4:879-95. [PMID: 26374494 PMCID: PMC4694138 DOI: 10.1002/mbo3.286] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 08/04/2015] [Accepted: 08/10/2015] [Indexed: 11/25/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of nosocomial infections. Its relatively impermeable outer membrane (OM) limits antibiotic entry, and a chromosomally encoded AmpC β‐lactamase inactivates β‐lactam antibiotics. AmpC expression is linked to peptidoglycan (PG) recycling, and soluble (sLT) or membrane‐bound (mLT) lytic transglycosylases are responsible for generating the anhydromuropeptides that induce AmpC expression. Thus, inhibition of LT activity could reduce AmpC‐mediated β‐lactam resistance in P. aeruginosa. Here, we characterized single and combination LT mutants. Strains lacking SltB1 or MltB had increased β‐lactam minimum inhibitory concentrations (MICs) compared to wild type, while only loss of Slt decreased MICs. An sltB1 mltB double mutant had elevated β‐lactam MICs compared to either the sltB1 or mltB single mutants (96 vs. 32 μg/mL cefotaxime), without changes to AmpC levels. Time–kill assays with β‐lactams suggested that increased MIC correlated with a slower rate of autolysis in the sltB1 mltB mutant – an antisuicide phenotype. Strains lacking multiple mLTs were more sensitive to β‐lactams and up to 16‐fold more sensitive to vancomycin, normally incapable of crossing the OM. Multi‐mLT mutants were also sensitive to bile salts and osmotic stress, and were hyperbiofilm formers, all phenotypes consistent with cell envelope compromise. Complementation with genes encoding inactive forms of the enzymes – or alternatively, overexpression of Braun's lipoprotein – reversed the mutants' cell envelope damage phenotypes, suggesting that mLTs help to stabilize the OM. We conclude that P. aeruginosa mLTs contribute physically to cell envelope stability, and that Slt is the preferred target for future development of LT inhibitors that could synergize with β‐lactams.
Collapse
Affiliation(s)
- Ryan P Lamers
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Uyen T Nguyen
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Ylan Nguyen
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Ryan N C Buensuceso
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
29
|
Role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins in AmpC expression, β-lactam resistance, and peptidoglycan structure. Antimicrob Agents Chemother 2015; 59:3925-34. [PMID: 25896695 DOI: 10.1128/aac.05150-14] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Accepted: 04/12/2015] [Indexed: 01/21/2023] Open
Abstract
This study aimed to characterize the role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins (LMM PBPs), namely, PBP4 (DacB), PBP5 (DacC), and PBP7 (PbpG), in peptidoglycan composition, β-lactam resistance, and ampC regulation. For this purpose, we constructed all single and multiple mutants of dacB, dacC, pbpG, and ampC from the wild-type P. aeruginosa PAO1 strain. Peptidoglycan composition was determined by high-performance liquid chromatography (HPLC), ampC expression by reverse transcription-PCR (RT-PCR), PBP patterns by a Bocillin FL-binding test, and antimicrobial susceptibility by MIC testing for a panel of β-lactams. Microscopy and growth rate analyses revealed no apparent major morphological changes for any of the mutants compared to the wild-type PAO1 strain. Of the single mutants, only dacC mutation led to significantly increased pentapeptide levels, showing that PBP5 is the major dd-carboxypeptidase in P. aeruginosa. Moreover, our results indicate that PBP4 and PBP7 play a significant role as dd-carboxypeptidase only if PBP5 is absent, and their dd-endopeptidase activity is also inferred. As expected, the inactivation of PBP4 led to a significant increase in ampC expression (around 50-fold), but, remarkably, the sequential inactivation of the three LMM PBPs produced a much greater increase (1,000-fold), which correlated with peptidoglycan pentapeptide levels. Finally, the β-lactam susceptibility profiles of the LMM PBP mutants correlated well with the ampC expression data. However, the inactivation of ampC in these mutants also evidenced a role of LMM PBPs, especially PBP5, in intrinsic β-lactam resistance. In summary, in addition to assessing the effect of P. aeruginosa LMM PBPs on peptidoglycan structure for the first time, we obtained results that represent a step forward in understanding the impact of these PBPs on β-lactam resistance, apparently driven by the interplay between their roles in AmpC induction, β-lactam trapping, and dd-carboxypeptidase/β-lactamase activity.
Collapse
|