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Barceló IM, Escobar-Salom M, Jordana-Lluch E, Torrens G, Oliver A, Juan C. Filling knowledge gaps related to AmpC-dependent β-lactam resistance in Enterobacter cloacae. Sci Rep 2024; 14:189. [PMID: 38167986 PMCID: PMC10762043 DOI: 10.1038/s41598-023-50685-1] [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: 11/17/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024] Open
Abstract
Enterobacter cloacae starred different pioneer studies that enabled the development of a widely accepted model for the peptidoglycan metabolism-linked regulation of intrinsic class C cephalosporinases, highly conserved in different Gram-negatives. However, some mechanistic and fitness/virulence-related aspects of E. cloacae choromosomal AmpC-dependent resistance are not completely understood. The present study including knockout mutants, β-lactamase cloning, gene expression analysis, characterization of resistance phenotypes, and the Galleria mellonella infection model fills these gaps demonstrating that: (i) AmpC enzyme does not show any collateral activity impacting fitness/virulence; (ii) AmpC hyperproduction mediated by ampD inactivation does not entail any biological cost; (iii) alteration of peptidoglycan recycling alone or combined with AmpC hyperproduction causes no attenuation of E. cloacae virulence in contrast to other species; (iv) derepression of E. cloacae AmpC does not follow a stepwise dynamics linked to the sequential inactivation of AmpD amidase homologues as happens in Pseudomonas aeruginosa; (v) the enigmatic additional putative AmpC-type β-lactamase generally present in E. cloacae does not contribute to the classical cephalosporinase hyperproduction-based resistance, having a negligible impact on phenotypes even when hyperproduced from multicopy vector. This study reveals interesting particularities in the chromosomal AmpC-related behavior of E. cloacae that complete the knowledge on this top resistance mechanism.
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Affiliation(s)
- Isabel M Barceló
- Health Research Institute of the Balearic Islands (IdISBa), 07010, Palma, Spain
- Microbiology Department, University Hospital Son Espases (HUSE), 07010, Palma, Spain
- Centro de Investigación Biomédica en Red, Área Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - María Escobar-Salom
- Health Research Institute of the Balearic Islands (IdISBa), 07010, Palma, Spain
- Microbiology Department, University Hospital Son Espases (HUSE), 07010, Palma, Spain
- Centro de Investigación Biomédica en Red, Área Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Elena Jordana-Lluch
- Health Research Institute of the Balearic Islands (IdISBa), 07010, Palma, Spain
- Microbiology Department, University Hospital Son Espases (HUSE), 07010, Palma, Spain
- Centro de Investigación Biomédica en Red, Área Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Gabriel Torrens
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, 901 87, Umeå, Sweden
| | - Antonio Oliver
- Health Research Institute of the Balearic Islands (IdISBa), 07010, Palma, Spain
- Microbiology Department, University Hospital Son Espases (HUSE), 07010, Palma, Spain
- Centro de Investigación Biomédica en Red, Área Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Carlos Juan
- Health Research Institute of the Balearic Islands (IdISBa), 07010, Palma, Spain.
- Microbiology Department, University Hospital Son Espases (HUSE), 07010, Palma, Spain.
- Centro de Investigación Biomédica en Red, Área Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, 28029, Madrid, Spain.
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Jones F, Hu Y, Coates A. The Efficacy of Using Combination Therapy against Multi-Drug and Extensively Drug-Resistant Pseudomonas aeruginosa in Clinical Settings. Antibiotics (Basel) 2022; 11:323. [PMID: 35326786 PMCID: PMC8944682 DOI: 10.3390/antibiotics11030323] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/19/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium which is capable of developing a high level of antibiotic resistance. It has been placed on the WHO's critical priority pathogen list and it is commonly found in ventilator-associated pneumonia infections, blood stream infections and other largely hospital-acquired illnesses. These infections are difficult to effectively treat due to their increasing antibiotic resistance and as such patients are often treated with antibiotic combination regimens. METHODS We conducted a systematic search with screening criteria using the Ovid search engine and the Embase, Ovid Medline, and APA PsycInfo databases. RESULTS It was found that in many cases the combination therapies were able to match or outperform the monotherapies and none performed noticeably worse than the monotherapies. However, the clinical studies were mostly small, only a few were prospective randomized clinical trials and statistical significance was lacking. CONCLUSIONS It was concluded that combination therapies have a place in the treatment of these highly resistant bacteria and, in some cases, there is some evidence to suggest that they provide a more effective treatment than monotherapies.
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Affiliation(s)
| | | | - Anthony Coates
- Institute for Infection and Immunity, St George’s University of London, London SW17 0RE, UK; (F.J.); (Y.H.)
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Thompson DK, Sharkady SM. Genomic Insights into Drug Resistance Determinants in Cedecea neteri, A Rare Opportunistic Pathogen. Microorganisms 2021; 9:microorganisms9081741. [PMID: 34442820 PMCID: PMC8401664 DOI: 10.3390/microorganisms9081741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/09/2021] [Accepted: 08/13/2021] [Indexed: 11/16/2022] Open
Abstract
Cedecea, a genus in the Enterobacteriaceae family, includes several opportunistic pathogens reported to cause an array of sporadic acute infections, most notably of the lung and bloodstream. One species, Cedecea neteri, is associated with cases of bacteremia in immunocompromised hosts and has documented resistance to different antibiotics, including β-lactams and colistin. Despite the potential to inflict serious infections, knowledge about drug resistance determinants in Cedecea is limited. In this study, we utilized whole-genome sequence data available for three environmental strains (SSMD04, M006, ND14a) of C. neteri and various bioinformatics tools to analyze drug resistance genes in this bacterium. All three genomes harbor multiple chromosome-encoded β-lactamase genes. A deeper analysis of β-lactamase genes in SSMD04 revealed four metallo-β-lactamases, a novel variant, and a CMY/ACT-type AmpC putatively regulated by a divergently transcribed AmpR. Homologs of known resistance-nodulation-cell division (RND)-type multidrug efflux pumps such as OqxB, AcrB, AcrD, and MdtBC were also identified. Genomic island prediction for SSMD04 indicated that tolC, involved in drug and toxin export across the outer membrane of Gram-negative bacteria, was acquired by a transposase-mediated genetic transfer mechanism. Our study provides new insights into drug resistance mechanisms of an environmental microorganism capable of behaving as a clinically relevant opportunistic pathogen.
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Abstract
MOTIVATION An important task in comparative genomics is to detect functional units by analyzing gene-context patterns. Colinear syntenic blocks (CSBs) are groups of genes that are consistently encoded in the same neighborhood and in the same order across a wide range of taxa. Such CSBs are likely essential for the regulation of gene expression in prokaryotes. Recent results indicate that colinearity can be conserved across multiple operons, thus motivating the discovery of multi-operon CSBs. This computational task raises scalability challenges in large datasets. RESULTS We propose an efficient algorithm for the discovery of cross-strand multi-operon CSBs in large genomic datasets. The proposed algorithm uses match-point arithmetic, which is scalable for large datasets of microbial genomes in terms of running time and space requirements. The algorithm is implemented and incorporated into a tool with a graphical user interface, called CSBFinder-S. We applied CSBFinder-S to data mine 1485 prokaryotic genomes and analyzed the identified cross-strand CSBs. Our results indicate that most of the syntenic blocks are exclusively colinear. Additional results indicate that transcriptional regulation by overlapping transcriptional genes is abundant in bacteria. We demonstrate the utility of CSBFinder-S to identify common function of the gene-pair PulEF in multiple contexts, including Type 2 Secretion System, Type 4 Pilus System and DNA uptake machinery. AVAILABILITY AND IMPLEMENTATION CSBFinder-S software and code are publicly available at https://github.com/dinasv/CSBFinder. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Dina Svetlitsky
- Department of Computer Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Tal Dagan
- Institute of Microbiology, Kiel University, Kiel 24118, Germany
| | - Michal Ziv-Ukelson
- Department of Computer Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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5
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Complex Response of the CpxAR Two-Component System to β-Lactams on Antibiotic Resistance and Envelope Homeostasis in Enterobacteriaceae. Antimicrob Agents Chemother 2020; 64:AAC.00291-20. [PMID: 32229490 DOI: 10.1128/aac.00291-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 03/17/2020] [Indexed: 01/17/2023] Open
Abstract
The Cpx stress response is widespread among Enterobacteriaceae We previously reported a mutation in cpxA in a multidrug-resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields a single-amino-acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxAY144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the effect of the intimate interconnection between the Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall-active antibiotic or by inactivating penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increases phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to cause abnormal accumulation of muropeptides (disaccharide-pentapeptide and N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycans caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular, the interaction between CpxA and CpxP, as a promising therapeutic target.
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Shaku M, Ealand C, Matlhabe O, Lala R, Kana BD. Peptidoglycan biosynthesis and remodeling revisited. ADVANCES IN APPLIED MICROBIOLOGY 2020; 112:67-103. [PMID: 32762868 DOI: 10.1016/bs.aambs.2020.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The bacterial peptidoglycan layer forms a complex mesh-like structure that surrounds the cell, imparting rigidity to withstand cytoplasmic turgor and the ability to tolerate stress. As peptidoglycan has been the target of numerous clinically successful antimicrobials such as penicillin, the biosynthesis, remodeling and recycling of this polymer has been the subject of much interest. Herein, we review recent advances in the understanding of peptidoglycan biosynthesis and remodeling in a variety of different organisms. In order for bacterial cells to grow and divide, remodeling of cross-linked peptidoglycan is essential hence, we also summarize the activity of important peptidoglycan hydrolases and how their functions differ in various species. There is a growing body of evidence highlighting complex regulatory mechanisms for peptidoglycan metabolism including protein interactions, phosphorylation and protein degradation and we summarize key recent findings in this regard. Finally, we provide an overview of peptidoglycan recycling and how components of this pathway mediate resistance to drugs. In the face of growing antimicrobial resistance, these recent advances are expected to uncover new drug targets in peptidoglycan metabolism, which can be used to develop novel therapies.
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Affiliation(s)
- Moagi Shaku
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Christopher Ealand
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Ofentse Matlhabe
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Rushil Lala
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa
| | - Bavesh D Kana
- Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa.
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Pachori P, Gothalwal R, Gandhi P. Emergence of antibiotic resistance Pseudomonas aeruginosa in intensive care unit; a critical review. Genes Dis 2019; 6:109-119. [PMID: 31194018 PMCID: PMC6545445 DOI: 10.1016/j.gendis.2019.04.001] [Citation(s) in RCA: 266] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/09/2019] [Indexed: 12/29/2022] Open
Abstract
The emergence of antibiotic resistant bacteria in the healthcare is a serious concern. In the Healthcare premises precisely intensive care unit are major sources of microbial diversity. Recent findings have demonstrated not only microbial diversity but also drug resistant microbes largely habitat in ICU. Pseudomonas aeruginosa found as a part of normal intestinal flora and a significant pathogen responsible for wide range of ICU acquired infection in critically ill patients. Nosocomial infection associated with this organism including gastrointestinal infection, urinary tract infections and blood stream infection. Infection caused by this organism are difficult to treat because of the presence of its innate resistance to many antibiotics (β-lactam and penem group of antibiotics), and its ability to acquire further resistance mechanism to multiple class of antibiotics, including Beta-lactams, aminoglycosides and fluoroquinolones. In the molecular evolution microbes adopted several mechanism to maintain genomic plasticity. The tool microbe use for its survival is mainly biofilm formation, quorum sensing, and horizontal gene transfer and enzyme promiscuity. Such genomic plasticity provide an ideal habitat to grow and survive in hearse environment mainly antibiotics pressure. This review focus on infection caused by Pseudomonas aeruginosa, its mechanisms of resistance and available treatment options. The present study provides a systemic review on major source of Pseudomonas aeruginosa in ICU. Further, study also emphasizes virulence gene/s associated with Pseudomonas aeruginosa genome for extended drug resistance. Study gives detailed overview of antibiotic drug resistance mechanism.
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Affiliation(s)
- Preeti Pachori
- Department of Biotechnology, Barkatullah University, Bhopal 462026, Madhya Pradesh, India
| | - Ragini Gothalwal
- Department of Biotechnology, Barkatullah University, Bhopal 462026, Madhya Pradesh, India
| | - Puneet Gandhi
- Department of Research, Bhopal Memorial Hospital and Research Centre (BMHRC), Bhopal 462037, Madhya Pradesh, India
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Esteban-Cuesta I, Dorn-In S, Drees N, Hölzel C, Gottschalk C, Gareis M, Schwaiger K. Antimicrobial resistance of Enterobacter cloacae complex isolates from the surface of muskmelons. Int J Food Microbiol 2019; 301:19-26. [PMID: 31071501 DOI: 10.1016/j.ijfoodmicro.2019.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/15/2019] [Accepted: 04/29/2019] [Indexed: 02/06/2023]
Abstract
The increasing antimicrobial resistance (AMR) among pathogenic and opportunistic pathogenic microorganisms is one of the main global public health problems. The consumption of food contaminated with such bacteria (ARB), especially of raw products, might result in the direct acquisition of ARB and in a spread of resistant bacteria along the food chain. The aim of the study was to characterize the antimicrobial susceptibility of potentially extended spectrum β-lactamase (ESBL) producing or AmpC resistant Enterobacteriaceae isolated from the surface of 147 muskmelons from wholesale and retail. A phenotypic analysis was carried out by using minimum inhibitory concentration (MIC) test strips for ESBL detection and MIC susceptibility plates against 14 antimicrobials. Furthermore, ESBL genes, sul-genes and plasmid-mediated AmpC resistance were analyzed by real-time PCR. Additionally, a further insight in the AmpC resistance of isolates of the Enterobacter cloacae complex (ECC) was obtained by analyzing the sequence of the ampC regulatory region (n = 15). A total of 73 potentially resistant Enterobacteriaceae were isolated from 56 muskmelons. Of these, 15 isolates of the ECC were suspicious for ESBL/AmpC resistance, and eleven thereof were positive for the AmpC family EBC. Phenotypic analysis showed diminished susceptibility against "critically" and "highly important" antimicrobials, according to the WHO classification. Furthermore, divergence in the ampC regulatory region was detected between the 15 isolates. These findings highlight the important role that raw produce might play in the transmission of antimicrobial resistances along the food chain.
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Affiliation(s)
- Irene Esteban-Cuesta
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany.
| | - Samart Dorn-In
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany
| | - Nathalie Drees
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany
| | - Christina Hölzel
- Institute of Animal Breeding and Husbandry, Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts University Kiel, Hermann-Rodewald-Str. 6, Kiel, Germany
| | - Christoph Gottschalk
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany
| | - Manfred Gareis
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany
| | - Karin Schwaiger
- Chair of Food Safety, Veterinary Faculty, Ludwig-Maximilians-University Munich, Schoenleutnerstrasse 8, 85764 Oberschleissheim, Germany
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Juan C, Torrens G, González-Nicolau M, Oliver A. Diversity and regulation of intrinsic β-lactamases from non-fermenting and other Gram-negative opportunistic pathogens. FEMS Microbiol Rev 2018; 41:781-815. [PMID: 29029112 DOI: 10.1093/femsre/fux043] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 08/18/2017] [Indexed: 01/22/2023] Open
Abstract
This review deeply addresses for the first time the diversity, regulation and mechanisms leading to mutational overexpression of intrinsic β-lactamases from non-fermenting and other non-Enterobacteriaceae Gram-negative opportunistic pathogens. After a general overview of the intrinsic β-lactamases described so far in these microorganisms, including circa. 60 species and 100 different enzymes, we review the wide array of regulatory pathways of these β-lactamases. They include diverse LysR-type regulators, which control the expression of β-lactamases from relevant nosocomial pathogens such as Pseudomonas aeruginosa or Stenothrophomonas maltophilia or two-component regulators, with special relevance in Aeromonas spp., along with other pathways. Likewise, the multiple mutational mechanisms leading to β-lactamase overexpression and β-lactam resistance development, including AmpD (N-acetyl-muramyl-L-alanine amidase), DacB (PBP4), MrcA (PPBP1A) and other PBPs, BlrAB (two-component regulator) or several lytic transglycosylases among others, are also described. Moreover, we address the growing evidence of a major interplay between β-lactamase regulation, peptidoglycan metabolism and virulence. Finally, we analyse recent works showing that blocking of peptidoglycan recycling (such as inhibition of NagZ or AmpG) might be useful to prevent and revert β-lactam resistance. Altogether, the provided information and the identified gaps should be valuable for guiding future strategies for combating multidrug-resistant Gram-negative pathogens.
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Affiliation(s)
- Carlos Juan
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases-Instituto de Investigación Sanitaria de Baleares (IdISBa), 07120 Palma, Illes Balears, Spain
| | - Gabriel Torrens
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases-Instituto de Investigación Sanitaria de Baleares (IdISBa), 07120 Palma, Illes Balears, Spain
| | - Mar González-Nicolau
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases-Instituto de Investigación Sanitaria de Baleares (IdISBa), 07120 Palma, Illes Balears, Spain
| | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases-Instituto de Investigación Sanitaria de Baleares (IdISBa), 07120 Palma, Illes Balears, Spain
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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
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Abstract
Peptidoglycan (PG) recycling allows Escherichia coli to reuse the massive amounts of sacculus components that are released during elongation. Goodell and Schwarz, in 1985, labeled E. coli cells with 3H-diaminopimelic acid (DAP) and chased. During the chase, the DAP pool dropped dramatically, whereas the precursor pool dropped only slightly. This could only occur if DAP from the sacculi was being used to produce more precursor. They calculated that the cells were recycling about 45% of their wall DAP (actually, 60% of the side walls, since the poles are stable). Thus, recycling was discovered. Goodell went on to show that the tripeptide, L-Ala-D-Glu-DAP, could be taken up via opp and used directly to form PG. It was subsequently shown that uptake was predominantly via a permease, AmpG, that was specific for GlcNAc-anhMurNAc with attached peptides. Eleven genes have been identified which appear to have as their sole function the recovery of degradation products from PG. PG represents only 2.5% of the cell mass, so the reason for this investment in recycling is obscure. Recycling enzymes exist that are specific for every bond in the principal product taken up by AmpG, namely, GlcNAc-anh-MurNAc-tetrapeptide. However, most of the tripeptide, L-Ala-D-Glu-DAP, is used by murein peptide ligase (Mpl) to form the precursor intermediate UDP-MurNAc-tripeptide. anh-MurNAc can be converted to GlcNAc by a two-step process and thus is available for use. Surprisingly, in the absence of AmpD, an enzyme that cleaves the anh-MurNAc-L-Ala bond, anh-MurNAc-tripeptide accumulates, resulting in induction of beta-lactamase. However, this has nothing to do with the induction of beta-lactamase by beta-lactam antibiotics. Uehara, Suefuji, and Park (unpublished data) have some evidence suggesting that murein pentapeptide may be involved. The presence of orthologs suggests that recycling also exists in many Gram-negative bacteria. Surprisingly, the ortholog search also revealed that all mammals may have an AmpG ortholog! Hence, mammalian AmpG may be involved in the process of innate immunity.
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Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex. Antimicrob Agents Chemother 2015; 59:7753-61. [PMID: 26438498 DOI: 10.1128/aac.01729-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/30/2015] [Indexed: 01/10/2023] Open
Abstract
Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-D-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets.
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13
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Luan Y, Li GL, Duo LB, Wang WP, Wang CY, Zhang HG, He F, He X, Chen SJ, Luo DT. DHA-1 plasmid-mediated AmpC β-lactamase expression and regulation of Klebsiella pnuemoniae isolates. Mol Med Rep 2014; 11:3069-77. [PMID: 25483576 DOI: 10.3892/mmr.2014.3054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 07/09/2014] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to investigate the regulatory mechanism of the AmpC enzyme by analyzing the construction and function of AmpCR, AmpE and AmpG genes in the Dhahran (DHA)‑1 plasmid of Klebsiella pneumoniae (K. pneumoniae). The production of AmpC and extended‑spectrum β‑lactamase (ESBL) were determined following the cefoxitin (FOX) inducing test for AmpC, preliminary screening and confirmation tests for ESBL in 10 DHA‑1 plasmid AmpC enzymes of K. pneumoniae strains. AmpCR, AmpD, AmpE and AmpG sequences were analyzed by polymerase chain reaction. The pACYC184‑X plasmid analysis system was established and examined by regulating the pAmpC enzyme expression. The electrophoretic bands of AmpCR, AmpD, AmpE and AmpG were expressed. Numerous mutations in AmpC + AmpR (AmpCR) and in the intergenic region cistron of AmpC‑AmpR, AmpD, AmpE and AmpG were observed. The homology of AmpC and AmpR, in relation to the Morganella morganii strain, was 99%, which was determined by comparing the gene sequences of Kp1 with those of Kp17 AmpCR. The specific combination of AmpR and labeled probe demonstrated a band retarded phenomenon and established a spatial model of AmpR. All the enzyme production strains demonstrated Val93→Ala in AmpG; six transmembrane domains were found in AmpE in all strains, with the exception of Kp1 and Kp4, which had only three transmembrane segments that were caused by mutation. The DHA‑1 plasmid AmpC enzymes encoded by plasmid are similar to the inducible chromosomal AmpC enzymes, which are also regulated by AmpD, AmpE, AmpR and AmpG.
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Affiliation(s)
- Ying Luan
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Gui-Ling Li
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Li-Bo Duo
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Wei-Ping Wang
- Medicine Laboratory, Department of Urology Surgery, Daqing Oilfield General Hospital, Daqing, Heilongjiang 163001, P.R. China
| | - Cheng-Ying Wang
- Medicine Laboratory, Department of Urology Surgery, Daqing Oilfield General Hospital, Daqing, Heilongjiang 163001, P.R. China
| | - He-Guang Zhang
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Fei He
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Xin He
- Department of Medicine Laboratory, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Shu-Juan Chen
- Department of Medicine Laboratory, Hospital of Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
| | - Dan-Ting Luo
- Department of Medicine Laboratory, The Fourth People's Hospital of Shenyang, Shenyang, Liaoning 110031, P.R. China
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14
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Distinct roles of major peptidoglycan recycling enzymes in β-Lactamase production in Shewanella oneidensis. Antimicrob Agents Chemother 2014; 58:6536-43. [PMID: 25136029 DOI: 10.1128/aac.03238-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
β-Lactam antibiotics were the earliest discovered and are the most widely used group of antibiotics that work by inactivating penicillin-binding proteins to inhibit peptidoglycan biosynthesis. As one of the most efficient defense strategies, many bacteria produce β-lactam-degrading enzymes, β-lactamases, whose biochemical functions and regulation have been extensively studied. A signal transduction pathway for β-lactamase induction by β-lactam antibiotics, consisting of the major peptidoglycan recycling enzymes and the LysR-type transcriptional regulator, AmpR, has been recently unveiled in some bacteria. Because inactivation of some of these proteins, especially the permease AmpG and the β-hexosaminidase NagZ, results in substantially elevated susceptibility to the antibiotics, these have been recognized as potential therapeutic targets. Here, we show a contrasting scenario in Shewanella oneidensis, in which the homologue of AmpR is absent. Loss of AmpG or NagZ enhances β-lactam resistance drastically, whereas other identified major peptidoglycan recycling enzymes are dispensable. Moreover, our data indicate that there exists a parallel signal transduction pathway for β-lactamase induction, which is independent of either AmpG or NagZ.
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15
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ampG gene of Pseudomonas aeruginosa and its role in β-lactamase expression. Antimicrob Agents Chemother 2010; 54:4772-9. [PMID: 20713660 DOI: 10.1128/aac.00009-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In enterobacteria, the ampG gene encodes a transmembrane protein (permease) that transports 1,6-GlcNAc-anhydro-MurNAc and the 1,6-GlcNAc-anhydro-MurNAc peptide from the periplasm to the cytoplasm, which serve as signal molecules for the induction of ampC β-lactamase. The role of AmpG as a transporter is also essential for cell wall recycling. Pseudomonas aeruginosa carries two AmpG homologues, AmpG (PA4393) and AmpGh1 (PA4218), with 45 and 41% amino acid sequence identity, respectively, to Escherichia coli AmpG, while the two homologues share only 19% amino acid identity. In P. aeruginosa strains PAO1 and PAK, inactivation of ampG drastically repressed the intrinsic β-lactam resistance while ampGh1 deletion had little effect on the resistance. Further, deletion of ampG in an ampD-null mutant abolished the high-level β-lactam resistance that is associated with the loss of AmpD activity. The cloned ampG gene is able to complement both the P. aeruginosa and the E. coli ampG mutants, while that of ampGh1 failed to do so, suggesting that PA4393 encodes the only functional AmpG protein in P. aeruginosa. We also demonstrate that the function of AmpG in laboratory strains of P. aeruginosa can effectively be inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP), causing an increased sensitivity to β-lactams among laboratory as well as clinical isolates of P. aeruginosa. Our results suggest that inhibition of the AmpG activity is a potential strategy for enhancing the efficacy of β-lactams against P. aeruginosa, which carries inducible chromosomal ampC, especially in AmpC-hyperproducing clinical isolates.
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16
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Antibacterial-resistant Pseudomonas aeruginosa: clinical impact and complex regulation of chromosomally encoded resistance mechanisms. Clin Microbiol Rev 2010; 22:582-610. [PMID: 19822890 DOI: 10.1128/cmr.00040-09] [Citation(s) in RCA: 1169] [Impact Index Per Article: 83.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Treatment of infectious diseases becomes more challenging with each passing year. This is especially true for infections caused by the opportunistic pathogen Pseudomonas aeruginosa, with its ability to rapidly develop resistance to multiple classes of antibiotics. Although the import of resistance mechanisms on mobile genetic elements is always a concern, the most difficult challenge we face with P. aeruginosa is its ability to rapidly develop resistance during the course of treating an infection. The chromosomally encoded AmpC cephalosporinase, the outer membrane porin OprD, and the multidrug efflux pumps are particularly relevant to this therapeutic challenge. The discussion presented in this review highlights the clinical significance of these chromosomally encoded resistance mechanisms, as well as the complex mechanisms/pathways by which P. aeruginosa regulates their expression. Although a great deal of knowledge has been gained toward understanding the regulation of AmpC, OprD, and efflux pumps in P. aeruginosa, it is clear that we have much to learn about how this resourceful pathogen coregulates different resistance mechanisms to overcome the antibacterial challenges it faces.
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17
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Abstract
This review focuses on the era of antibiosis that led to a better understanding of bacterial morphology, in particular the cell wall component peptidoglycan. This is an effort to take readers on a tour de force from the concept of antibiosis, to the serendipity of antibiotics, evolution of beta-lactam development, and the molecular biology of antibiotic resistance. These areas of research have culminated in a deeper understanding of microbiology, particularly in the area of bacterial cell wall synthesis and recycling. In spite of this knowledge, which has enabled design of new even more effective therapeutics to combat bacterial infection and has provided new research tools, antibiotic resistance remains a worldwide health care problem.
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Affiliation(s)
- Kok-Fai Kong
- Department of Biological Sciences, Florida International University, Miami, FL, USA
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18
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Antibacterial-resistant Pseudomonas aeruginosa: clinical impact and complex regulation of chromosomally encoded resistance mechanisms. Clin Microbiol Rev 2009. [PMID: 19822890 DOI: 10.1128/cmr.00040-09.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Treatment of infectious diseases becomes more challenging with each passing year. This is especially true for infections caused by the opportunistic pathogen Pseudomonas aeruginosa, with its ability to rapidly develop resistance to multiple classes of antibiotics. Although the import of resistance mechanisms on mobile genetic elements is always a concern, the most difficult challenge we face with P. aeruginosa is its ability to rapidly develop resistance during the course of treating an infection. The chromosomally encoded AmpC cephalosporinase, the outer membrane porin OprD, and the multidrug efflux pumps are particularly relevant to this therapeutic challenge. The discussion presented in this review highlights the clinical significance of these chromosomally encoded resistance mechanisms, as well as the complex mechanisms/pathways by which P. aeruginosa regulates their expression. Although a great deal of knowledge has been gained toward understanding the regulation of AmpC, OprD, and efflux pumps in P. aeruginosa, it is clear that we have much to learn about how this resourceful pathogen coregulates different resistance mechanisms to overcome the antibacterial challenges it faces.
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19
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Kotsakis SD, Papagiannitsis CC, Tzelepi E, Tzouvelekis LS, Miriagou V. Extended-spectrum properties of CMY-30, a Val211Gly mutant of CMY-2 cephalosporinase. Antimicrob Agents Chemother 2009; 53:3520-3. [PMID: 19470510 PMCID: PMC2715598 DOI: 10.1128/aac.00219-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 05/03/2009] [Accepted: 05/17/2009] [Indexed: 01/25/2023] Open
Abstract
CMY-30, a Val211Gly mutant of CMY-2 cephalosporinase, was derived by mutagenesis. The hydrolytic efficiency of CMY-30 against expanded-spectrum cephalosporins was higher than that of CMY-2 due to increased k(cat) values. Findings indicate a role of the Omega loop residue 211 in determining the substrate specificities of CMYs also corroborated by modeling studies.
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Affiliation(s)
- Stathis D Kotsakis
- Laboratory of Bacteriology, Hellenic Pasteur Institute, Vas. Sofias 127, Athens 11521, Greece
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20
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Strateva T, Yordanov D. Pseudomonas aeruginosa - a phenomenon of bacterial resistance. J Med Microbiol 2009; 58:1133-1148. [PMID: 19528173 DOI: 10.1099/jmm.0.009142-0] [Citation(s) in RCA: 431] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is one of the leading nosocomial pathogens worldwide. Nosocomial infections caused by this organism are often hard to treat because of both the intrinsic resistance of the species (it has constitutive expression of AmpC beta-lactamase and efflux pumps, combined with a low permeability of the outer membrane), and its remarkable ability to acquire further resistance mechanisms to multiple groups of antimicrobial agents, including beta-lactams, aminoglycosides and fluoroquinolones. P. aeruginosa represents a phenomenon of bacterial resistance, since practically all known mechanisms of antimicrobial resistance can be seen in it: derepression of chromosomal AmpC cephalosporinase; production of plasmid or integron-mediated beta-lactamases from different molecular classes (carbenicillinases and extended-spectrum beta-lactamases belonging to class A, class D oxacillinases and class B carbapenem-hydrolysing enzymes); diminished outer membrane permeability (loss of OprD proteins); overexpression of active efflux systems with wide substrate profiles; synthesis of aminoglycoside-modifying enzymes (phosphoryltransferases, acetyltransferases and adenylyltransferases); and structural alterations of topoisomerases II and IV determining quinolone resistance. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. This review describes the known resistance mechanisms in P. aeruginosa to the most frequently administrated antipseudomonal antibiotics: beta-lactams, aminoglycosides and fluoroquinolones.
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Affiliation(s)
- Tanya Strateva
- Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria
| | - Daniel Yordanov
- Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria
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21
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AmpDI is involved in expression of the chromosomal L1 and L2 beta-lactamases of Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2009; 53:2902-7. [PMID: 19414581 DOI: 10.1128/aac.01513-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two ampD homologues, ampD(I) and ampD(II), of Stenotrophomonas maltophilia have been cloned and analyzed. Comparative genomic analysis revealed that the genomic context of the ampD(II) genes is quite different, whereas that of the ampD(I) genes is more conserved in S. maltophilia strains. The ampD system of S. maltophilia is distinct from that of the Enterobacteriaceae and Pseudomonas aeruginosa in three respects. (i) AmpD(I) of S. maltophilia is not encoded in an ampDE operon, in contrast to what happens in the Enterobacteriaceae and P. aeruginosa. (ii) The AmpD systems of the Enterobacteriaceae and P. aeruginosa are generally involved in the regulation of ampR-linked ampC gene expression, while AmpD(I) of S. maltophilia is responsible for the regulation of two intrinsic beta-lactamase genes, of which the L2 gene, but not the L1 gene, is linked to ampR. (iii) S. maltophilia exhibits a one-step L1 and L2 gene derepression model involving ampD(I), distinct from the two- or three-step derepression of the Enterobacteriaceae and P. aeruginosa. Moreover, the ampD(I) and ampD(II) genes are constitutively expressed and not regulated by the inducer and AmpR protein, and the expression of ampD(II) is weaker than that of ampD(I). Finally, AmpD(II) is not associated with the derepression of beta-lactamases, and its role in S. maltophilia remains unclear.
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22
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Moya B, Dötsch A, Juan C, Blázquez J, Zamorano L, Haussler S, Oliver A. Beta-lactam resistance response triggered by inactivation of a nonessential penicillin-binding protein. PLoS Pathog 2009; 5:e1000353. [PMID: 19325877 PMCID: PMC2654508 DOI: 10.1371/journal.ppat.1000353] [Citation(s) in RCA: 214] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 02/26/2009] [Indexed: 02/01/2023] Open
Abstract
It has long been recognized that the modification of penicillin-binding proteins (PBPs) to reduce their affinity for β-lactams is an important mechanism (target modification) by which Gram-positive cocci acquire antibiotic resistance. Among Gram-negative rods (GNR), however, this mechanism has been considered unusual, and restricted to clinically irrelevant laboratory mutants for most species. Using as a model Pseudomonas aeruginosa, high up on the list of pathogens causing life-threatening infections in hospitalized patients worldwide, we show that PBPs may also play a major role in β-lactam resistance in GNR, but through a totally distinct mechanism. Through a detailed genetic investigation, including whole-genome analysis approaches, we demonstrate that high-level (clinical) β-lactam resistance in vitro, in vivo, and in the clinical setting is driven by the inactivation of the dacB-encoded nonessential PBP4, which behaves as a trap target for β-lactams. The inactivation of this PBP is shown to determine a highly efficient and complex β-lactam resistance response, triggering overproduction of the chromosomal β-lactamase AmpC and the specific activation of the CreBC (BlrAB) two-component regulator, which in turn plays a major role in resistance. These findings are a major step forward in our understanding of β-lactam resistance biology, and, more importantly, they open up new perspectives on potential antibiotic targets for the treatment of infectious diseases. Decades after their discovery, β-lactams remain key components of our antimicrobial armamentarium for the treatment of infectious diseases. Nevertheless, resistance to these antibiotics is increasing alarmingly. There are two major bacterial strategies to develop resistance to β-lactam antibiotics: the production of enzymes that inactivate them (β-lactamases), or the modification of their targets in the cell wall (the essential penicillin-binding proteins, PBPs). Using the pathogen Pseudomonas aeruginosa as a model microorganism, we show that high-level (clinical) β-lactam resistance in vitro and in vivo frequently occurs through a previously unrecognized, totally distinct resistance pathway, driven by the mutational inactivation of a nonessential PBP (PBP4) that behaves as a trap target for β-lactams. We show that mutation of this PBP determines a highly efficient and complex β-lactam resistance response, triggering overproduction of the chromosomal β-lactamase AmpC and the specific activation of a two-component regulator, which in turn plays a key role in resistance. These findings are a major step forward in our understanding of β-lactam resistance biology, and, more importantly, they open up new perspectives on potential antibiotic targets for the treatment of infectious diseases.
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Affiliation(s)
- Bartolomé Moya
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Dureta, Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS) Palma de Mallorca, Spain
| | - Andreas Dötsch
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Carlos Juan
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Dureta, Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS) Palma de Mallorca, Spain
| | - Jesús Blázquez
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Campus UAM, Madrid, Spain
| | - Laura Zamorano
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Dureta, Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS) Palma de Mallorca, Spain
| | | | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Dureta, Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS) Palma de Mallorca, Spain
- * E-mail:
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23
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How bacteria consume their own exoskeletons (turnover and recycling of cell wall peptidoglycan). Microbiol Mol Biol Rev 2008; 72:211-27, table of contents. [PMID: 18535144 DOI: 10.1128/mmbr.00027-07] [Citation(s) in RCA: 305] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
SUMMARY The phenomenon of peptidoglycan recycling is reviewed. Gram-negative bacteria such as Escherichia coli break down and reuse over 60% of the peptidoglycan of their side wall each generation. Recycling of newly made peptidoglycan during septum synthesis occurs at an even faster rate. Nine enzymes, one permease, and one periplasmic binding protein in E. coli that appear to have as their sole function the recovery of degradation products from peptidoglycan, thereby making them available for the cell to resynthesize more peptidoglycan or to use as an energy source, have been identified. It is shown that all of the amino acids and amino sugars of peptidoglycan are recycled. The discovery and properties of the individual proteins and the pathways involved are presented. In addition, the possible role of various peptidoglycan degradation products in the induction of beta-lactamase is discussed.
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24
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Papagiannitsis CC, Tzouvelekis LS, Tzelepi E, Miriagou V. Plasmid-encoded ACC-4, an extended-spectrum cephalosporinase variant from Escherichia coli. Antimicrob Agents Chemother 2007; 51:3763-7. [PMID: 17664321 PMCID: PMC2043296 DOI: 10.1128/aac.00389-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ACC-4, an omega loop mutant (Val(211)-->Gly) of the Hafnia alvei-derived cephalosporinase ACC-1, was encoded by an Escherichia coli plasmid. The genetic environment of bla(ACC-4) shared similarities with plasmidic regions carrying bla(ACC-1). Kinetics of beta-lactam hydrolysis and levels of resistance to beta-lactams showed that ACC-4 was more effective than ACC-1 against expanded-spectrum cephalosporins.
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25
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Juan C, Moyá B, Pérez JL, Oliver A. Stepwise upregulation of the Pseudomonas aeruginosa chromosomal cephalosporinase conferring high-level beta-lactam resistance involves three AmpD homologues. Antimicrob Agents Chemother 2006; 50:1780-7. [PMID: 16641450 PMCID: PMC1472203 DOI: 10.1128/aac.50.5.1780-1787.2006] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Development of resistance to the antipseudomonal penicillins and cephalosporins mediated by hyperproduction of the chromosomal cephalosporinase AmpC is a major threat to the successful treatment of Pseudomonas aeruginosa infections. Although ampD inactivation has been previously found to lead to a partially derepressed phenotype characterized by increased AmpC production but retaining further inducibility, the regulation of ampC in P. aeruginosa is far from well understood. We demonstrate that ampC expression is coordinately repressed by three AmpD homologues, including the previously described protein AmpD plus two additional proteins, designated AmpDh2 and AmpDh3. The three AmpD homologues are responsible for a stepwise ampC upregulation mechanism ultimately leading to constitutive hyperexpression of the chromosomal cephalosporinase and high-level antipseudomonal beta-lactam resistance, as shown by analysis of the three single ampD mutants, the three double ampD mutants, and the triple ampD mutant. This is achieved by a three-step escalating mechanism rendering four relevant expression states: basal-level inducible expression (wild type), moderate-level hyperinducible expression with increased antipseudomonal beta-lactam resistance (ampD mutant), high-level hyperinducible expression with high-level beta-lactam resistance (ampD ampDh3 double mutant), and very high-level (more than 1,000-fold compared to the wild type) derepressed expression (triple mutant). Although one-step inducible-derepressed expression models are frequent in natural resistance mechanisms, this is the first characterized example in which expression of a resistance gene can be sequentially amplified through multiple steps of derepression.
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Affiliation(s)
- Carlos Juan
- Servicio de Microbiología, Hospital Son Dureta, C. Andrea Doria No. 55, 07014 Palma de Mallorca, Spain
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26
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Juan C, Maciá MD, Gutiérrez O, Vidal C, Pérez JL, Oliver A. Molecular mechanisms of beta-lactam resistance mediated by AmpC hyperproduction in Pseudomonas aeruginosa clinical strains. Antimicrob Agents Chemother 2006; 49:4733-8. [PMID: 16251318 PMCID: PMC1280133 DOI: 10.1128/aac.49.11.4733-4738.2005] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular mechanisms of beta-lactam resistance mediated by AmpC hyperproduction in natural strains of Pseudomonas aeruginosa were investigated in a collection of 10 isogenic, ceftazidime-susceptible and -resistant pairs of isolates, each sequentially recovered from a different intensive care unit patient treated with beta-lactams. All 10 ceftazidime-resistant mutants hyper-produced AmpC (beta-lactamase activities were 12- to 657-fold higher than those of the parent strains), but none of them harbored mutations in ampR or the ampC-ampR intergenic region. On the other hand, six of them harbored inactivating mutations in ampD: four contained frameshift mutations, one had a C-->T mutation, creating a premature stop codon, and finally, one had a large deletion, including the complete ampDE region. Complementation studies revealed that only three of the six ampD mutants could be fully trans-complemented with either ampD- or ampDE-harboring plasmids, whereas one of them could be trans-complemented only with ampDE and two of them (including the mutant with the deletion of the ampDE region and one with an ampD frameshift mutation leading to an ampDE-fused open reading frame) could not be fully trans-complemented with any of the plasmids. Finally, one of the four mutants with no mutations in ampD could be trans-complemented, but only with ampDE. Although the inactivation of AmpD is found to be the most frequent mechanism of AmpC hyperproduction in clinical strains, our findings suggest that for certain types of mutations, AmpE plays an indirect role in resistance and that there are other unknown genes involved in AmpC hyperproduction, with at least one of them apparently located close to the ampDE operon.
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Affiliation(s)
- Carlos Juan
- Servicio de Microbiología, Hospital Son Dureta, C. Andrea Doria No. 55, 07014 Palma de Mallorca, Spain
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27
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Nash KA, Zhang Y, Brown-Elliott BA, Wallace RJ. Molecular basis of intrinsic macrolide resistance in clinical isolates of Mycobacterium fortuitum. J Antimicrob Chemother 2004; 55:170-7. [PMID: 15590712 PMCID: PMC1472656 DOI: 10.1093/jac/dkh523] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Some clinical isolates of Mycobacterium fortuitum are naturally resistant to macrolides, e.g. clarithromycin. Thus, the aim of this study was to identify the gene(s) conferring this resistance. METHODS M. fortuitum ATCC 6841T DNA libraries were screened for plasmids that complemented the macrolide-susceptible phenotype of Mycobacterium smegmatis variant ermKO4 [erm(38)-negative]. Macrolide-resistant M. smegmatis transformants were selected on agar containing 128 mg/L erythromycin. RESULTS Genetic complementation identified an M. fortuitum rRNA methylase gene, termed erm(39), 69% identical to erm(38) of M. smegmatis. In addition, erm(39) was found to be in the same chromosomal location as erm(38) in their respective hosts. Like erm(38), erm(39) conferred resistance (MIC >128 mg/L) to macrolide-lincosamide (ML) agents, but not to streptogramin B. Analysis of erm gene expression in M. fortuitum showed that ML agents increased erm(39) RNA levels, reaching a steady state level approximately 20-fold higher than baseline. Screening of 32 M. fortuitum clinical isolates by PCR showed that all were positive for erm(39), irrespective of clarithromycin susceptibility. A majority of clarithromycin-susceptible (MIC < or = 2 mg/L) isolates were postulated to carry a disabled erm(39) gene as they had a GTG-->CTG mutation in the putative initiation codon of the erm(39) gene. CONCLUSIONS The similarity of the erm genes of M. smegmatis and M. fortuitum suggests that they were inherited from a common ancestor. Although the clinical impact of erm(39) on the therapeutic utility of clarithromycin is unclear, induction of this gene is consistent with the trailing end-points commonly seen during susceptibility testing of M. fortuitum isolates against macrolides.
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Affiliation(s)
- Kevin A Nash
- Department of Pathology, University of Southern California, and Saban Research Institute of Childrens Hospital Los Angeles, Los Angeles, CA, USA.
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28
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Miriagou V, Tzouvelekis LS, Villa L, Lebessi E, Vatopoulos AC, Carattoli A, Tzelepi E. CMY-13, a novel inducible cephalosporinase encoded by an Escherichia coli plasmid. Antimicrob Agents Chemother 2004; 48:3172-4. [PMID: 15273143 PMCID: PMC478546 DOI: 10.1128/aac.48.8.3172-3174.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An IncN plasmid (p541) from Escherichia coli carried a Citrobacter freundii-derived sequence of 4,252 bp which included an ampC-ampR region and was bound by two directly repeated IS26 elements. ampC encoded a novel cephalosporinase (CMY-13) with activity similar to that of CMY-2. AmpR was likely functional as indicated in induction experiments.
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Affiliation(s)
- V Miriagou
- Laboratory of Bacteriology, Hellenic Pasteur Institute, Athens, Greece.
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29
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Nakano R, Okamoto R, Nakano Y, Kaneko K, Okitsu N, Hosaka Y, Inoue M. CFE-1, a novel plasmid-encoded AmpC beta-lactamase with an ampR gene originating from Citrobacter freundii. Antimicrob Agents Chemother 2004; 48:1151-8. [PMID: 15047515 PMCID: PMC375250 DOI: 10.1128/aac.48.4.1151-1158.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A clinical isolate of Escherichia coli from a patient in Japan, isolate KU6400, was found to produce a plasmid-encoded beta-lactamase that conferred resistance to extended-spectrum cephalosporins and cephamycins. Resistance arising from production of a beta-lactamase could be transferred by either conjugation or transformation with plasmid pKU601 into E. coli ML4947. The substrate and inhibition profiles of this enzyme resembled those of the AmpC beta-lactamase. The resistance gene of pKU601, which was cloned and expressed in E. coli, proved to contain an open reading frame showing 99.8% DNA sequence identity with the ampC gene of Citrobacter freundii GC3. DNA sequence analysis also identified a gene upstream of ampC whose sequence was 99.0% identical to the ampR gene from C. freundii GC3. In addition, a fumarate operon (frdABCD) and an outer membrane lipoprotein (blc) surrounding the ampR-ampC genes in C. freundii were identified, and insertion sequence (IS26) elements were observed on both sides of the sequences identified (forming an IS26 composite transposon); these results confirm the evidence of the translocation of a beta-lactamase-associated gene region from the chromosome to a plasmid. Finally, we describe a novel plasmid-encoded AmpC beta-lactamase, CFE-1, with an ampR gene derived from C. freundii.
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Affiliation(s)
- Ryuichi Nakano
- Department of Microbiology, School of Medicine and Environmental Infectious Disease, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Kanagawa, Japan
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30
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Barnaud G, Benzerara Y, Gravisse J, Raskine L, Sanson-Le Pors MJ, Labia R, Arlet G. Selection during cefepime treatment of a new cephalosporinase variant with extended-spectrum resistance to cefepime in an Enterobacter aerogenes clinical isolate. Antimicrob Agents Chemother 2004; 48:1040-2. [PMID: 14982805 PMCID: PMC353102 DOI: 10.1128/aac.48.3.1040-1042.2004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterobacter aerogenes resistant to cefepime (MIC, 32 microg/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC beta-lactamase (MIC of cefepime, 0.5 microg/ml). The AmpC beta-lactamase of the resistant strain had an L-293-P amino acid substitution and a high k(cat)/K(m) ratio for cefepime. Both of these modifications were necessary for resistance to cefepime.
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Affiliation(s)
- G Barnaud
- Service de Bactériologie, Hôpital Tenon AP-H, Hôpital Lariboisière AP-HP, Paris.
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31
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Goldstein FW. Cephalosporinase induction and cephalosporin resistance: a longstanding misinterpretation. Clin Microbiol Infect 2002; 8:823-5. [PMID: 12519358 DOI: 10.1046/j.1469-0691.2002.00492.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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32
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Petrosino JF, Pendleton AR, Weiner JH, Rosenberg SM. Chromosomal system for studying AmpC-mediated beta-lactam resistance mutation in Escherichia coli. Antimicrob Agents Chemother 2002; 46:1535-9. [PMID: 11959593 PMCID: PMC127180 DOI: 10.1128/aac.46.5.1535-1539.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In some enterobacterial pathogens, but not in Escherichia coli, loss-of-function mutations in the ampD gene are a common route to beta-lactam antibiotic resistance. We constructed an assay system for studying mechanism(s) of enterobacterial ampD mutation using the well-developed genetics of E. coli. We integrated the Enterobacter ampRC genes into the E. coli chromosome. These cells acquire spontaneous recombination- and SOS response-independent beta-lactam resistance mutations in ampD. This chromosomal system is useful for studying mutation mechanisms that promote antibiotic resistance.
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Affiliation(s)
- Joseph F Petrosino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030-3411, USA.
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33
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Liassine N, Madec S, Ninet B, Metral C, Fouchereau-Peron M, Labia R, Auckenthaler R. Postneurosurgical meningitis due to Proteus penneri with selection of a ceftriaxone-resistant isolate: analysis of chromosomal class A beta-lactamase HugA and its LysR-type regulatory protein HugR. Antimicrob Agents Chemother 2002; 46:216-9. [PMID: 11751137 PMCID: PMC126972 DOI: 10.1128/aac.46.1.216-219.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report on a case of a postneurosurgical meningitis due to ceftriaxone-susceptible Proteus penneri, with selection of a ceftriaxone-resistant isolate following treatment with ceftriaxone. The isolates presented identical patterns by pulsed-field gel electrophoresis and produced a single beta-lactamase named HugA with an isoelectric point of 6.7. The ceftriaxone-resistant isolate hyperproduced the beta-lactamase (increase in the level of production, about 90-fold). The sequences of the hugA beta-lactamase gene and its regulator, hugR, were identical in both P. penneri strains and had 85.96% homology with those of Proteus vulgaris. The HugA beta-lactamase belongs to molecular class A, and the transcriptional regulator HugR belongs to the LysR family.
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Affiliation(s)
- Nadia Liassine
- Central Laboratory of Bacteriology, University Hospital, Geneva, Switzerland.
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34
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Naas T, Massuard S, Garnier F, Nordmann P. AmpD is required for regulation of expression of NmcA, a carbapenem-hydrolyzing beta-lactamase of Enterobacter cloacae. Antimicrob Agents Chemother 2001; 45:2908-15. [PMID: 11557489 PMCID: PMC90751 DOI: 10.1128/aac.45.10.2908-2915.2001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To further elucidate the induction process of the carbapenem-hydrolyzing beta-lactamase of Ambler class A, NmcA, ampD genes of the wild-type (WT) strain and of ceftazidime-resistant mutants of Enterobacter cloacae NOR-1 were cloned and tested in transcomplementation experiments. Ceftazidime-resistant E. cloacae NOR-1 mutants exhibited derepressed expression of the AmpC-type cephalosporinase and of the carbapenem-hydrolyzing beta-lactamase NmcA. The ampD genes of Escherichia coli and E. cloacae WT NOR-1 transcomplemented the ceftazidime-resistant E. cloacae NOR-1 mutants to the WT level of beta-lactamase expression, while the mutated ampD alleles of E. cloacae NOR-1 failed to do so. The deduced E. cloacae NOR-1 WT AmpD protein exhibited 95 and 91% amino acid identity with the E. cloacae O29 and E. cloacae 14 WT AmpD proteins, respectively. Of the 12 ceftazidime-resistant E. cloacae NOR-1 strains, 3 had AmpD proteins with amino acid changes, while the others had truncated AmpD proteins. Most of these mutations were located outside the conserved regions that link the AmpD proteins to the cell wall hydrolases. AmpD from E. cloacae NOR-1 is involved in the regulation of expression of both beta-lactamases (NmcA and AmpC), suggesting that structurally unrelated genes may be under the control of an identical genetic system.
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Affiliation(s)
- T Naas
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique-Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre Cedex, France.
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35
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Barnaud G, Labia R, Raskine L, Sanson-Le Pors MJ, Philippon A, Arlet G. Extension of resistance to cefepime and cefpirome associated to a six amino acid deletion in the H-10 helix of the cephalosporinase of an Enterobacter cloacae clinical isolate. FEMS Microbiol Lett 2001; 195:185-90. [PMID: 11179650 DOI: 10.1111/j.1574-6968.2001.tb10519.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Enterobacter cloacae CHE, a clinical strain with overproduced cephalosporinase was found to be highly resistant to the new cephalosporins, cefepime and cefpirome (MICs> or =128 microg ml(-1)). The strain was isolated from a child previously treated with cefepime. The catalytic efficiency of the purified enzyme with the third-generation cephalosporins, cefepime and cefpirome, was 10 times higher than that with the E. cloacae P99 enzyme. This was mostly due to a decrease in K(m) for these beta-lactams. The clinical isolate produced large amounts of the cephalosporinase because introduction of the ampD gene decreased ampC expression and partially restored the wild-type phenotype. Indeed, MICs of cefepime and cefpirome remained 10 times higher than those for a stable derepressed clinical isolate (OUDhyp) transformed with an ampD gene. Sequencing of the ampC gene showed that 18 nucleotides had been deleted, corresponding to the six amino acids SKVALA (residues 289--294). According to the crystal structure of P99 beta-lactamase, this deletion was located in the H-10 helix. The ampR-ampC genes from the clinical isolates CHE and OUDhyp were cloned and expressed in Escherichia coli JM101. The MICs of cefpirome and cefepime of E. coli harboring ampC and ampR genes from CHE were 100--200 times higher than those of E. coli harboring ampC and ampR genes from OUDhyp. This suggests that the deletion, confirmed by sequencing of the ampC gene, is involved in resistance to cefepime and cefpirome. However, the high level of resistance to cefepime and cefpirome observed in the E. cloacae clinical isolate was due to a combination of hyperproduction of the AmpC beta-lactamase and structural modification of the enzyme. This is the first example of an AmpC variant conferring resistance to cefepime and cefpirome, isolated as a clinical strain.
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Affiliation(s)
- G Barnaud
- Service de Bactériologie-Virologie, Hôpital Lariboisière, Paris, France
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36
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Núñez C, Moreno S, Cárdenas L, Soberón-Chávez G, Espín G. Inactivation of the ampDE operon increases transcription of algD and affects morphology and encystment of Azotobacter vinelandii. J Bacteriol 2000; 182:4829-35. [PMID: 10940024 PMCID: PMC111360 DOI: 10.1128/jb.182.17.4829-4835.2000] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription of algD, encoding GDP-mannose dehydrogenase, the key enzyme in the alginate biosynthetic pathway, is highly regulated in Azotobacter vinelandii. We describe here the characterization of a Tn5 insertion mutant (AC28) which shows a higher level of expression of an algD::lacZ fusion. AC28 cells were morphologically abnormal and unable to encyst. The cloning and nucleotide sequencing of the Tn5-disrupted locus in AC28 revealed an operon homologous to the Escherichia coli ampDE operon. Tn5 was located within the ampD gene, encoding a cytosolic N-acetyl-anhydromuramyl-L-alanine amidase that participates in the intracellular recycling of peptidoglycan fragments. The ampE gene encodes a transmembrane protein, but the function of the protein is not known. We constructed strains carrying ampD or ampE mutations and one with an ampDE deletion. The strain with a deletion of the ampDE operon showed a phenotype similar to that of mutant AC28. The present work demonstrates that both alginate production and bacterial encystment are greatly influenced by the bacterial ability to recycle its cell wall.
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Affiliation(s)
- C Núñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca Morelos 62250, México
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37
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Girlich D, Naas T, Bellais S, Poirel L, Karim A, Nordmann P. Biochemical-genetic characterization and regulation of expression of an ACC-1-like chromosome-borne cephalosporinase from Hafnia alvei. Antimicrob Agents Chemother 2000; 44:1470-8. [PMID: 10817695 PMCID: PMC89899 DOI: 10.1128/aac.44.6.1470-1478.2000] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A naturally occurring AmpC beta-lactamase (cephalosporinase) gene was cloned from the Hafnia alvei 1 clinical isolate and expressed in Escherichia coli. The deduced AmpC beta-lactamase (ACC-2) had a pI of 8 and a relative molecular mass of 37 kDa and showed 50 and 47% amino acid identity with the chromosome-encoded AmpCs from Serratia marcescens and Providentia stuartii, respectively. It had 94% amino acid identity with the recently described plasmid-borne cephalosporinase ACC-1 from Klebsiella pneumoniae, suggesting the chromosomal origin of ACC-1. The hydrolysis constants (k(cat) and K(m)) showed that ACC-2 was a peculiar cephalosporinase, since it significantly hydrolyzed cefpirome. Once its gene was cloned and expressed in E. coli (pDEL-1), ACC-2 conferred resistance to ceftazidime and cefotaxime but also an uncommon reduced susceptibility to cefpirome. A divergently transcribed ampR gene with an overlapping promoter compared with ampC (bla(ACC-2)) was identified in H. alvei 1, encoding an AmpR protein that shared 64% amino acid identity with the closest AmpR protein from P. stuartii. beta-Lactamase induction experiments showed that the ampC gene was repressed in the absence of ampR and was activated when cefoxitin or imipenem was added as an inducer. From H. alvei 1 cultures that expressed an inducible-cephalosporinase phenotype, several ceftazidime- and cefpirome-cross-resistant H. alvei 1 mutants were obtained upon selection on cefpirome- or ceftazidime-containing plates, and H. alvei 1 DER, a ceftazidime-resistant mutant, stably overproduced cephalosporinase. Transformation of H. alvei 1 DER or E. coli JRG582 (ampDE mutant) harboring ampC and ampR from H. alvei 1 with a recombinant plasmid containing ampD from E. coli resulted in a decrease in the MIC of beta-lactam and recovery of an inducible phenotype for H. alvei 1 DER. Thus, AmpR and AmpD proteins may regulate biosynthesis of the H. alvei cephalosporinase similarly to other enterobacterial cephalosporinases.
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Affiliation(s)
- D Girlich
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre cedex, France
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38
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Langaee TY, Gagnon L, Huletsky A. Inactivation of the ampD gene in Pseudomonas aeruginosa leads to moderate-basal-level and hyperinducible AmpC beta-lactamase expression. Antimicrob Agents Chemother 2000; 44:583-9. [PMID: 10681322 PMCID: PMC89730 DOI: 10.1128/aac.44.3.583-589.2000] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It has been shown in enterobacteria that mutations in ampD provoke hyperproduction of chromosomal beta-lactamase, which confers to these organisms high levels of resistance to beta-lactam antibiotics. In this study, we investigated whether this genetic locus was implicated in the altered AmpC beta-lactamase expression of selected clinical isolates and laboratory mutants of Pseudomonas aeruginosa. The sequences of the ampD genes and promoter regions from these strains were determined and compared to that of wild-type ampD from P. aeruginosa PAO1. Although we identified numerous nucleotide substitutions, they resulted in few amino acid changes. The phenotypes produced by these mutations were ascertained by complementation analysis. The data revealed that the ampD genes of the P. aeruginosa mutants transcomplemented Escherichia coli ampD mutants to the same levels of beta-lactam resistance and beta-lactamase expression as wild-type ampD. Furthermore, complementation of the P. aeruginosa mutants with wild-type ampD did not restore the inducibility of beta-lactamase to wild-type levels. This shows that the amino acid substitutions identified in AmpD do not cause the altered phenotype of AmpC beta-lactamase expression in the P. aeruginosa mutants. The effects of AmpD inactivation in P. aeruginosa PAO1 were further investigated by gene replacement. This resulted in moderate-basal-level and hyperinducible expression of beta-lactamase accompanied by high levels of beta-lactam resistance. This differs from the stably derepressed phenotype reported in AmpD-defective enterobacteria and suggests that further change at another unknown genetic locus may be causing total derepressed AmpC production. This genetic locus could also be altered in the P. aeruginosa mutants studied in this work.
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Affiliation(s)
- T Y Langaee
- Centre de Recherche en Infectiologie, Université Laval, Québec, Canada G1V 4G2
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39
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Poirel L, Guibert M, Girlich D, Naas T, Nordmann P. Cloning, sequence analyses, expression, and distribution of ampC-ampR from Morganella morganii clinical isolates. Antimicrob Agents Chemother 1999; 43:769-76. [PMID: 10103179 PMCID: PMC89205 DOI: 10.1128/aac.43.4.769] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Shotgun cloning experiments with restriction enzyme-digested genomic DNA from Morganella morganii 1, which expresses high levels of cephalosporinase, into the pBKCMV cloning vector gave a recombinant plasmid, pPON-1, which encoded four entire genes: ampC, ampR, an hybF family gene, and orf-1 of unknown function. The deduced AmpC beta-lactamase of pI 7.6 shared structural and functional homologies with AmpC from Citrobacter freundii, Escherichia coli, Yersinia enterocolitica, Enterobacter cloacae, and Serratia marcescens. The overlapping promoter organization of ampC and ampR, although much shorter in M. morganii than in the other enterobacterial species, suggested similar AmpR regulatory properties. The MICs of beta-lactams for E. coli MC4100 (ampC mutant) harboring recombinant plasmid pACYC184 containing either ampC and ampR (pAC-1) or ampC (pAC-2) and induction experiments showed that the ampC gene of M. morganii 1 was repressed in the presence of ampR and was activated when a beta-lactam inducer was added. Moreover, transformation of M. morganii 1 or of E. coli JRG582 (delta ampDE) harboring ampC and ampR with a recombinant plasmid containing ampD from E. cloacae resulted in a decrease in the beta-lactam MICs and an inducible phenotype for M. morganii 1, thus underlining the role of an AmpD-like protein in the regulation of the M. morganii cephalosporinase. Fifteen other M. morganii clinical isolates with phenotypes of either low-level inducible cephalosporinase expression or high-level constitutive cephalosporinase expression harbored the same ampC-ampR organization, with the hybF and orf-1 genes surrounding them; the organization of these genes thus differed from those of ampC-ampR genes in C. freundii and E. cloacae, which are located downstream from the fumarate operon. Finally, an identical AmpC beta-lactamase (DHA-1) was recently identified as being plasmid encoded in Salmonella enteritidis, and this is confirmatory evidence of a chromosomal origin of the plasmid-mediated cephalosporinases.
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Affiliation(s)
- L Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Faculté de Médecine Paris-Sud, Le Kremlin-Bicêtre, France
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40
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Langaee TY, Dargis M, Huletsky A. An ampD gene in Pseudomonas aeruginosa encodes a negative regulator of AmpC beta-lactamase expression. Antimicrob Agents Chemother 1998; 42:3296-300. [PMID: 9835532 PMCID: PMC106040 DOI: 10.1128/aac.42.12.3296] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The ampD and ampE genes of Pseudomonas aeruginosa PAO1 were cloned and characterized. These genes are transcribed in the same orientation and form an operon. The deduced polypeptide of P. aeruginosa ampD exhibited more than 60% similarity to the AmpD proteins of enterobacteria and Haemophilus influenzae. The ampD product transcomplemented Escherichia coli ampD mutants to wild-type beta-lactamase expression.
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Affiliation(s)
- T Y Langaee
- Département de biologie médicale, Pavillon Marchand, Université Laval, Ste-Foy, Québec, Canada G1K 7P4
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41
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Abstract
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715-1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
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Affiliation(s)
- M K Berlyn
- Department of Biology and School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06520-8104, USA.
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42
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Mainardi JL, Mugnier P, Coutrot A, Buu-Hoï A, Collatz E, Gutmann L. Carbapenem resistance in a clinical isolate of Citrobacter freundii. Antimicrob Agents Chemother 1997; 41:2352-4. [PMID: 9371332 PMCID: PMC164127 DOI: 10.1128/aac.41.11.2352] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Carbapenem resistance was studied in two sets of Citrobacter freundii strains: (i) strain CFr950, resistant to imipenem (MIC, 16 microg/ml) and isolated in vivo during imipenem therapy, and strain CFr950-Rev, the spontaneous, imipenem-susceptible revertant of CFr950 selected in vitro, and (ii) strains CFr801 and CFr802, two imipenem-resistant mutants selected in vitro from the susceptible clinical isolate CFr800. In all strains, whether they were imipenem-susceptible or -resistant strains, production of the cephalosporinase was derepressed and their Km values for cephaloridine were in the range of 128 to 199 microM. No carbapenemase activity was detected in vitro. The role of cephalosporinase overproduction in the resistance was demonstrated after introduction of the ampD gene which decreased the level of production of cephalosporinase at least 250-fold and resulted in an 8- to 64-fold decrease in the MICs of the carbapenems. The role of reduced permeability in the resistance was suggested by the absence, in CFr950 and CFr802, of two outer membrane proteins (the 42- and 40-kDa putative porins whose levels were considerably decreased in CFr801) and the reappearance of the 42-kDa protein in imipenem-susceptible strain CFr950-Rev. This role was confirmed after introduction of the ompF gene of Escherichia coli into the CFr strains, which resulted in 8- to 16-fold decreases in the MICs of carbapenems for CFr802 and CFr950. We infer from these results that the association of reduced, porin-mediated permeability with high-level cephalosporinase production, observed previously in other gram-negative bacteria, may also confer carbapenem resistance on C. freundii.
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Affiliation(s)
- J L Mainardi
- Service de Microbiologie Clinique, Hôpital Saint-Joseph, Paris, France
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43
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Kadima TA, Weiner JH. Mechanism of suppression of piperacillin resistance in enterobacteria by tazobactam. Antimicrob Agents Chemother 1997; 41:2177-83. [PMID: 9333044 PMCID: PMC164089 DOI: 10.1128/aac.41.10.2177] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Resistance to piperacillin in several isolates of Citrobacter freundii and Enterobacter cloacae was investigated and confirmed to occur at a frequency of 10(-7) to 10(-6). Development of resistance to piperacillin was significantly suppressed by tazobactam but not by clavulanic acid. To elucidate the mechanism by which resistance suppression occurs, the effect of piperacillin plus tazobactam on the induction of AmpC beta-lactamase was analyzed by monitoring the beta-galactosidase activity of an inducible ampC-lacZ gene fusion in Escherichia coli. The combination exerted no inhibitory effect on AmpC beta-lactamase induction. Tazobactam also had no effect on the accumulation of a key intermediate in the AmpC beta-lactamase induction pathway, 1,6-anhydromurotripeptide, in an ampD mutant strain of E. coli. However, the addition of tazobactam to liquid cultures of E. cloacae 40001 in the presence of piperacillin at four times the MIC caused a delay in the recovery of the culture to piperacillin-induced stress. At 16 times the MIC, a complete suppression of regrowth occurred. Analysis of culture viability on piperacillin plates showed that the culture recovery was due to growth by moderately resistant mutants preexisting in the cell population, which at 16 times the MIC became susceptible to the combination. Evidence from the kinetics of inhibition of the E. cloacae 40001 AmpC beta-lactamase by clavulanic acid, sulbactam, and tazobactam and from the effects of these drugs on the frequency of resistance to piperacillin suggests that the suppressive effect of tazobactam on the appearance of resistance is primarily mediated by the beta-lactamase inhibitory activity.
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Affiliation(s)
- T A Kadima
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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44
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Nicolas-Chanoine M. Impact of β-lactamases on the clinical use of β-lactam antibiotics. Int J Antimicrob Agents 1996; 7 Suppl 1:S21-6. [DOI: 10.1016/0924-8579(96)00315-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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45
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Stapleton P, Shannon K, Phillips I. DNA sequence differences of ampD mutants of Citrobacter freundii. Antimicrob Agents Chemother 1995; 39:2494-8. [PMID: 8585732 PMCID: PMC162971 DOI: 10.1128/aac.39.11.2494] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Three groups of mutants with increased levels of beta-lactamase synthesis were selected from Citrobacter freundii 382010 by beta-lactam antibiotics at concentrations just above the MIC. Uninduced cultures of the hyperinducible group had 3- to 5-fold more beta-lactamase activity than the parent strain, with one mutant (termed type b) expressing 19 times the activity of the parent strain; the partially derepressed group had a relative 55-fold increase, while fully derepressed strains exhibited a 460-fold increase. Upon induction by growth in the presence of cefoxitin (32 micrograms/ml) for 2 h, the hyperinducible and derepressed groups had similar relative beta-lactamase activities of 650 and 725, respectively. Induction of beta-lactamase activity from partially derepressed mutants resulted in a relative activity of only 240. The ampD gene including its promoter region was amplified from the parent strain and the mutant strains by PCR. The sequence of ampD from the parent strain showed only three nucleotide changes from a previously published sequence, none of which resulted in a change to the deduced amino acid sequence. Hyperinducible mutant strains of type a had an amino acid change of either a tryptophan in codon 95 to an arginine (Trp-95-->Arg) (three mutants) or Ala-158-->Asp (one mutant). The hyperinducible type b strain had the change Tyr-102-->Asp. The derepressed strains had the following changes: Val-33-->Gly (one mutant), Asp-164-->Glu (one mutant), and Trp-95-->termination codon (two mutants). We infer that the amino acid changes in the hyperinducible mutants result in altered AmpD activity, whereas, in contrast, they lead to an inactive protein in derepressed mutants. No nucleotide differences were found in the ampD gene from partially derepressed strains.
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Affiliation(s)
- P Stapleton
- Department of Microbiology, United Medical and Dental School, London, United Kingdom
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Schmidt H, Korfmann G, Barth H, Martin HH. The signal transducer encoded by ampG is essential for induction of chromosomal AmpC beta-lactamase in Escherichia coli by beta-lactam antibiotics and 'unspecific' inducers. MICROBIOLOGY (READING, ENGLAND) 1995; 141 ( Pt 5):1085-1092. [PMID: 7773404 DOI: 10.1099/13500872-141-5-1085] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Chemical mutagenesis of the AmpC beta-lactamase-hyperinducible Escherichia coli strain SN0301/pNu305 carrying the cloned ampC and ampR genes from Citrobacter freundii OS60 gave four independent mutants in which beta-lactamase was no longer inducible, or was inducible only to a low level, by beta-lactam antibiotics. The genes ampC, ampR, ampD and ampE, which were essential for beta-lactamase induction, were functional in these mutants. In all four mutants, the sites of mutation were mapped to 9.9 min on the E. coli chromosome. Complementation with wild-type ampG restored inducibility of beta-lactamase to wild-type levels. The nucleotide sequence of all four mutant ampG alleles (ampG1, ampG3, ampG4 and ampG5) was determined. In three of the mutants, a single base exchange led to an amino acid change from glycine to aspartate at different sites in the deduced amino acid sequence. In the fourth mutant (ampG4), with low-level inducibility, the nucleotide sequence was identical to wild-type ampG. Spontaneous back-mutation of the chromosomal ampG1 mutant resulted in restoration of wild-type inducibility and a return to the wild-type ampG sequence. Unspecific induction by components of the growth medium was also dependent on intact ampG function.
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Affiliation(s)
- Herbert Schmidt
- Institut fr Mikrobiologie, Technische Hochschule, 64287 Darmstadt, Germany
| | | | - Holger Barth
- Institut fr Mikrobiologie, Technische Hochschule, 64287 Darmstadt, Germany
| | - Hans H Martin
- Institut fr Mikrobiologie, Technische Hochschule, 64287 Darmstadt, Germany
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Jacobs C, Joris B, Jamin M, Klarsov K, Van Beeumen J, Mengin-Lecreulx D, van Heijenoort J, Park JT, Normark S, Frère JM. AmpD, essential for both beta-lactamase regulation and cell wall recycling, is a novel cytosolic N-acetylmuramyl-L-alanine amidase. Mol Microbiol 1995; 15:553-9. [PMID: 7783625 DOI: 10.1111/j.1365-2958.1995.tb02268.x] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In enterobacteria, the ampD gene encodes a cytosolic protein which acts as a negative regulator of beta-lactamase expression. It is shown here that the AmpD protein is a novel N-acetylmuramyl-L-alanine amidase (E.C.3.5.1.28) participating in the intracellular recycling of peptidoglycan fragments. Surprisingly, AmpD exhibits an exclusive specificity for substrates containing anhydro muramic acid. This anhydro bond is mainly found in the peptidoglycan degradation products formed by the periplasmic lytic transglycosylases and thus might behave as a 'recycling tag' allowing the enzyme to distinguish these fragments from the newly synthesized peptidoglycan precursors. The AmpD substrate (or substrates) which accumulates in the absence of the corresponding enzymatic activity acts as an intracellular positive effector for beta-lactamase expression and might represent an element of a communication network between the chromosome and the cell wall peptidoglycan.
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Affiliation(s)
- C Jacobs
- Centre d'Ingénierie des Protéines, Université de Liège, Belgium
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48
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Whitchurch CB, Mattick JS. Escherichia coli contains a set of genes homologous to those involved in protein secretion, DNA uptake and the assembly of type-4 fimbriae in other bacteria. Gene 1994; 150:9-15. [PMID: 7959070 DOI: 10.1016/0378-1119(94)90851-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A specialised system involved in a diverse array of functions, including the biogenesis of fimbriae, protein secretion and DNA uptake, has recently been found to be widespread in the eubacteria. These systems have in common several sets of related genes, including those encoding proteins containing leader sequences homologous to that of the type-4 fimbrial subunit (prepilin), a prepilin-type leader peptidase, a cytoplasmic nucleotide-binding protein, and other proteins located in the inner and outer membranes [Hobbs, M. and Mattick, J.S., Mol Microbiol. 10 (1993) 233-243]. Here, we show that Escherichia coli contains at least nine homologs of this system, and present complete sequence data for five of the genes involved (ppdD. hopB, hopC, hopD and pshM), as well as for an adjacent gene (nadC), which encodes quinolic acid phosphoribosyltransferase. Insertional mutagenesis of hopB and hopD failed to reveal any obvious effects on cell viability, morphogenesis of M13 phage, conjugative transfer of the F plasmid, or protein secretion.
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Affiliation(s)
- C B Whitchurch
- Centre for Molecular Biology and Biotechnology, University of Queensland, Brisbane, Australia
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Datz M, Joris B, Azab EA, Galleni M, Van Beeumen J, Frère JM, Martin HH. A common system controls the induction of very different genes. The class-A beta-lactamase of Proteus vulgaris and the enterobacterial class-C beta-lactamase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:149-57. [PMID: 7957242 DOI: 10.1111/j.1432-1033.1994.tb20036.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Among the Enterobacteriaceae, Proteus vulgaris is exceptional in the inducible production of a 29-kDa beta-lactamase (cefuroximase) with an unusually high activity towards the beta-lactamase-stable oximino-cephalosporins (e.g. cefuroxime and cefotaxime). Sequencing of the corresponding gene, cumA, showed that the derived CumA beta-lactamase belonged to the molecular class A. The structural gene was under the direct control of gene cumR, which was transcribed backwards and whose initiation codon was 165 bp away from that of the beta-lactamase gene. This resembled the arrangement of structural and regulator genes ampC and ampR of the 39-kDa molecular-class-C beta-lactamase AmpC present in many enterobacteria. Moreover, cloned genes ampD and ampG for negative modulation and signal transduction of AmpC beta-lactamase induction, respectively, were also able to restore constitutively CumA overproducing and non-inducible P. vulgaris mutants to the inducible, wild-type phenotype. The results indicate that controls of the induction phenomena are equivalent for the CumA and AmpC beta-lactamase. Very different structural genes can thus be under the control of identical systems.
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Affiliation(s)
- M Datz
- Laboratoire d'Enzymologie, Université de Liège, Sart Tilman, Belgium
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Rather PN, Orosz E. Characterization of aarA, a pleiotrophic negative regulator of the 2'-N-acetyltransferase in Providencia stuartii. J Bacteriol 1994; 176:5140-4. [PMID: 8051030 PMCID: PMC196357 DOI: 10.1128/jb.176.16.5140-5144.1994] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have utilized transposon mutagenesis to obtain insertional mutations in Providencia stuartii that activate the chromosomal aac(2')-la gene. Two closely linked mini-Tn5Cm insertions were obtained in a locus designated aarA, and a single insertion was obtained in a separate locus, aarC. Nucleotide sequence analysis, complementation studies, and localization of the sites of mini-Tn5Cm insertion have allowed the identification of the aarA coding region. The deduced AarA protein had a molecular mass of 31,086 kDa and displayed characteristics of an integral membrane protein. A strain deleted for the aarA gene by allelic exchange showed at least a fourfold increase in the accumulation of aac(2')-la mRNA and an eightfold increase in aminoglycoside resistance. Mutations in aarA were pleiotrophic and also resulted in loss of pigmentation and a deficiency in cell separation during division.
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Affiliation(s)
- P N Rather
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
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