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McGinn J, Wen A, Edwards DL, Brinkley DM, Lamason RL. An expanded genetic toolkit for inducible expression and targeted gene silencing in Rickettsia parkeri. J Bacteriol 2024; 206:e0009124. [PMID: 38842342 PMCID: PMC11270864 DOI: 10.1128/jb.00091-24] [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: 03/14/2024] [Accepted: 05/14/2024] [Indexed: 06/07/2024] Open
Abstract
Pathogenic species within the Rickettsia genus are transmitted to humans through arthropod vectors and cause a spectrum of diseases ranging from mild to life-threatening. Despite rickettsiae posing an emerging global health risk, the genetic requirements of their infectious life cycles remain poorly understood. A major hurdle toward building this understanding has been the lack of efficient tools for genetic manipulation, owing to the technical difficulties associated with their obligate intracellular nature. To this end, we implemented the Tet-On system to enable conditional gene expression in Rickettsia parkeri. Using Tet-On, we show inducible expression of antibiotic resistance and a fluorescent reporter. We further used this inducible promoter to screen the ability of R. parkeri to express four variants of the catalytically dead Cas9 (dCas9). We demonstrate that all four dCas9 variants can be expressed in R. parkeri and used for CRISPR interference (CRISPRi)-mediated targeted gene knockdown. We show targeted knockdown of an antibiotic resistance gene as well as the endogenous virulence factor sca2. Altogether, we have developed systems for inducible gene expression and CRISPRi-mediated gene knockdown for the first time in rickettsiae, laying the groundwork for more scalable, targeted mechanistic investigations into their infectious life cycles.IMPORTANCEThe spotted fever group of Rickettsia contains vector-borne pathogenic bacteria that are neglected and emerging threats to public health. Due to the obligate intracellular nature of rickettsiae, the development of tools for genetic manipulation has been stunted, and the molecular and genetic underpinnings of their infectious lifecycle remain poorly understood. Here, we expand the genetic toolkit by introducing systems for conditional gene expression and CRISPR interference (CRISPRi)-mediated gene knockdown. These systems allow for relatively easy manipulation of rickettsial gene expression. We demonstrate the effectiveness of these tools by disrupting the intracellular life cycle using CRISPRi to deplete the sca2 virulence factor. These tools will be crucial for building a more comprehensive and detailed understanding of rickettsial biology and pathogenesis.
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Affiliation(s)
- Jon McGinn
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Annie Wen
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Desmond L. Edwards
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - David M. Brinkley
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca L. Lamason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Filipek J, Chalaskiewicz K, Kosmider A, Nielipinski M, Michalak A, Bednarkiewicz M, Goslawski-Zeligowski M, Prucnal F, Sekula B, Pietrzyk-Brzezinska AJ. Comprehensive structural overview of the C-terminal ligand-binding domains of the TetR family regulators. J Struct Biol 2024; 216:108071. [PMID: 38401830 DOI: 10.1016/j.jsb.2024.108071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/20/2024] [Accepted: 02/20/2024] [Indexed: 02/26/2024]
Abstract
TetR family regulators (TFRs) represent a large group of one-component bacterial signal transduction systems which recognize environmental signals, like the presence of antibiotics or other bactericidal compounds, and trigger the cell response by regulating the expression of genes that secure bacterial survival in harsh environmental conditions. TFRs act as homodimers, each protomer is composed of a conserved DNA-binding N-terminal domain (NTD) and a variable ligand-binding C-terminal domain (CTD). Currently, there are about 500 structures of TFRs available in the Protein Data Bank and one-fourth of them represent the structures of TFR-ligand complexes. In this review, we summarized information on the ligands interacting with TFRs and based on structural data, we compared the CTDs of the TFR family members, as well as their ligand-binding cavities. Additionally, we divided the whole TFR family, including more than half of a million sequences, into subfamilies according to calculated multiple sequence alignment and phylogenetic tree. We also highlighted structural elements characteristic of some of the subfamilies. The presented comprehensive overview of the TFR CTDs provides good bases and future directions for further studies on TFRs that are not only important targets for battling multidrug resistance but also good candidates for many biotechnological approaches, like TFR-based biosensors.
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Affiliation(s)
- Jakub Filipek
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Katarzyna Chalaskiewicz
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland; Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 2/22, Lodz 90-537, Poland
| | - Aleksandra Kosmider
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Maciej Nielipinski
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland; Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 2/22, Lodz 90-537, Poland
| | - Agnieszka Michalak
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Maria Bednarkiewicz
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Mieszko Goslawski-Zeligowski
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Filip Prucnal
- Biotechnology Students Association Ferment, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Wolczanska 171/173, 90-530 Lodz, Poland
| | - Bartosz Sekula
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 2/22, Lodz 90-537, Poland
| | - Agnieszka J Pietrzyk-Brzezinska
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 2/22, Lodz 90-537, Poland.
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Kittl S, Brodard I, Tresch M, Perreten V. Novel tetracycline resistance gene tet(65) located on a multi-resistance Corynebacterium plasmid. J Antimicrob Chemother 2024; 79:1023-1029. [PMID: 38497972 PMCID: PMC11062942 DOI: 10.1093/jac/dkae066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 02/23/2024] [Indexed: 03/19/2024] Open
Abstract
BACKGROUND Corynebacterium (C.) sp. 22KM0430 related to C. oculi and isolated from a dog exhibited resistance to tetracycline, and its WGS analysis revealed a putative resistance gene on a 35 562-bp plasmid also harbouring the MLSB resistance gene erm(X). OBJECTIVES To characterize the novel tetracycline resistance gene tet(65) and demonstrate its functionality by expression in C. glutamicum and Escherichia coli and plasmid curing of the host strain. METHODS tet(65) was cloned with and without its repressor tetR(65) and expressed in C. glutamicum DSM20300 and E. coli DH5α. Plasmid was cured by non-selective passages. Minimal inhibitory concentrations (MICs) of tetracyclines were determined according to CLSI guidelines. Association of tet(65) with efflux was shown by the addition of reserpine to MIC assays. Phylogenetic position and transmembrane structure of Tet(65) were analysed using MEGA11 and DeepTMHMM. RESULTS Tet(65) shows 73% amino acid identity with the closest related Tet(Z), contains 12 transmembrane domains and is structurally related to the Major Facilitator Superfamily. The tetracycline MICs decreased in the plasmid-cured strain and increased when tet(65) was expressed in C. glutamicum and in E. coli. The MICs of tetracycline decreased in the presence of reserpine indicating that tet(65) functions as an efflux pump. A GenBank search also identified tet(65) in C. diphtheriae and Brevibacterium (B.) casei and B. luteolum. CONCLUSIONS A novel tetracycline efflux gene tet(65) was identified in a C. oculi related species and was also present in the human pathogen C. diphtheriae and in Brevibacterium species indicating broader potential for dissemination.
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Affiliation(s)
- Sonja Kittl
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Isabelle Brodard
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Milena Tresch
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Vincent Perreten
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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McGinn J, Wen A, Edwards DL, Brinkley DM, Lamason RL. An expanded genetic toolkit for inducible expression and targeted gene silencing in Rickettsia parkeri. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.15.585227. [PMID: 38559073 PMCID: PMC10980030 DOI: 10.1101/2024.03.15.585227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Pathogenic species within the Rickettsia genus are transmitted to humans through arthropod vectors and cause a spectrum of diseases ranging from mild to life-threatening. Despite rickettsiae posing an emerging global health risk, the genetic requirements of their infectious life cycles remain poorly understood. A major hurdle toward building this understanding has been the lack of efficient tools for genetic manipulation, owing to the technical difficulties associated with their obligate intracellular nature. To this end, we implemented the Tet-On system to enable conditional gene expression in Rickettsia parkeri. Using Tet-On, we show inducible expression of antibiotic resistance and a fluorescent reporter. We further used this inducible promoter to screen the ability of R. parkeri to express four variants of the catalytically dead Cas9 (dCas9). We demonstrate that all four dCas9 variants can be expressed in R. parkeri and used for CRISPR interference (CRISPRi)-mediated targeted gene knockdown. We show targeted knockdown of an antibiotic resistance gene as well as the endogenous virulence factor sca2. Altogether, we have developed systems for inducible gene expression and CRISPRi-mediated gene knockdown for the first time in rickettsiae, laying the groundwork for more scalable, targeted mechanistic investigations into their infectious life cycles.
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Affiliation(s)
- Jon McGinn
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Annie Wen
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Desmond L Edwards
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - David M Brinkley
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca L Lamason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Asensio‐Calavia A, Ceballos‐Munuera Á, Méndez‐Pérez A, Álvarez B, Fernández LÁ. A tuneable genetic switch for tight control of tac promoters in Escherichia coli boosts expression of synthetic injectisomes. Microb Biotechnol 2024; 17:e14328. [PMID: 37608576 PMCID: PMC10832536 DOI: 10.1111/1751-7915.14328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/27/2023] [Accepted: 08/02/2023] [Indexed: 08/24/2023] Open
Abstract
Biosafety of engineered bacteria as living therapeutics requires a tight regulation to control the specific delivery of protein effectors, maintaining minimum leakiness in the uninduced (OFF) state and efficient expression in the induced (ON) state. Here, we report a three repressors (3R) genetic circuit that tightly regulates the expression of multiple tac promoters (Ptac) integrated in the chromosome of E. coli and drives the expression of a complex type III secretion system injectisome for therapeutic protein delivery. The 3R genetic switch is based on the tetracycline repressor (TetR), the non-inducible lambda repressor cI (ind-) and a mutant lac repressor (LacIW220F ) with higher activity. The 3R switch was optimized with different protein translation and degradation signals that control the levels of LacIW220F . We demonstrate the ability of an optimized switch to fully repress the strong leakiness of the Ptac promoters in the OFF state while triggering their efficient activation in the ON state with anhydrotetracycline (aTc), an inducer suitable for in vivo use. The implementation of the optimized 3R switch in the engineered synthetic injector E. coli (SIEC) strain boosts expression of injectisomes upon aTc induction, while maintaining a silent OFF state that preserves normal growth in the absence of the inducer. Since Ptac is a commonly used promoter, the 3R switch may have multiple applications for tight control of protein expression in E. coli. In addition, the modularity of the 3R switch may enable its tuning for the control of Ptac promoters with different inducers.
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Affiliation(s)
- Alejandro Asensio‐Calavia
- Department of Microbial Biotechnology, Centro Nacional de BiotecnologíaConsejo Superior de Investigaciones Científicas (CNB‐CSIC)MadridSpain
| | - Álvaro Ceballos‐Munuera
- Department of Microbial Biotechnology, Centro Nacional de BiotecnologíaConsejo Superior de Investigaciones Científicas (CNB‐CSIC)MadridSpain
- Programa de Doctorado en Biociencias MolecularesUniversidad Autónoma de Madrid (UAM)MadridSpain
| | - Almudena Méndez‐Pérez
- Department of Microbial Biotechnology, Centro Nacional de BiotecnologíaConsejo Superior de Investigaciones Científicas (CNB‐CSIC)MadridSpain
- Programa de Doctorado en Biociencias MolecularesUniversidad Autónoma de Madrid (UAM)MadridSpain
| | - Beatriz Álvarez
- Department of Microbial Biotechnology, Centro Nacional de BiotecnologíaConsejo Superior de Investigaciones Científicas (CNB‐CSIC)MadridSpain
| | - Luis Ángel Fernández
- Department of Microbial Biotechnology, Centro Nacional de BiotecnologíaConsejo Superior de Investigaciones Científicas (CNB‐CSIC)MadridSpain
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Perez-Bou L, Muñoz-Palazon B, Gonzalez-Lopez J, Gonzalez-Martinez A, Correa-Galeote D. Deciphering the Role of WWTPs in Cold Environments as Hotspots for the Dissemination of Antibiotic Resistance Genes. MICROBIAL ECOLOGY 2023; 87:14. [PMID: 38091083 DOI: 10.1007/s00248-023-02325-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023]
Abstract
Cold environments are the most widespread extreme habitats in the world. However, the role of wastewater treatment plants (WWTPs) in the cryosphere as hotspots in antibiotic resistance dissemination has not been well established. Hence, a snapshot of the resistomes of WWTPs in cold environments, below 5 °C, was provided to elucidate their role in disseminating antibiotic resistance genes (ARGs) to the receiving waterbodies. The resistomes of two natural environments from the cold biosphere were also determined. Quantitative PCR analysis of the aadA, aadB, ampC, blaSHV, blaTEM, dfrA1, ermB, fosA, mecA, qnrS, and tetA(A) genes indicated strong prevalences of these genetic determinants in the selected environments, except for the mecA gene, which was not found in any of the samples. Notably, high abundances of the aadA, ermB, and tetA(A) genes were found in the influents and activated sludge, highlighting that WWTPs of the cryosphere are critical hotspots for disseminating ARGs, potentially worsening the resistance of bacteria to some of the most commonly prescribed antibiotics. Besides, the samples from non-disturbed cold environments had large quantities of ARGs, although their ARG profiles were highly dissimilar. Hence, the high prevalences of ARGs lend support to the fact that antibiotic resistance is a common issue worldwide, including environmentally fragile cold ecosystems.
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Affiliation(s)
- Lizandra Perez-Bou
- Department of Microbiology and Virology, Faculty of Biology, University of Havana, Havana, Cuba
- Microbiology and Environmental Technologies Section, Water Research Institute, University of Granada, Granada, Spain
| | - Barbara Muñoz-Palazon
- Microbiology and Environmental Technologies Section, Water Research Institute, University of Granada, Granada, Spain
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Jesus Gonzalez-Lopez
- Microbiology and Environmental Technologies Section, Water Research Institute, University of Granada, Granada, Spain
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Alejandro Gonzalez-Martinez
- Microbiology and Environmental Technologies Section, Water Research Institute, University of Granada, Granada, Spain
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - David Correa-Galeote
- Microbiology and Environmental Technologies Section, Water Research Institute, University of Granada, Granada, Spain.
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain.
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Merritt J, Kreth J. Illuminating the oral microbiome and its host interactions: tools and approaches for molecular microbiology studies. FEMS Microbiol Rev 2023; 47:fuac050. [PMID: 36549660 PMCID: PMC10719069 DOI: 10.1093/femsre/fuac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Advancements in DNA sequencing technologies within the last decade have stimulated an unprecedented interest in the human microbiome, largely due the broad diversity of human diseases found to correlate with microbiome dysbiosis. As a direct consequence of these studies, a vast number of understudied and uncharacterized microbes have been identified as potential drivers of mucosal health and disease. The looming challenge in the field is to transition these observations into defined molecular mechanistic studies of symbiosis and dysbiosis. In order to meet this challenge, many of these newly identified microbes will need to be adapted for use in experimental models. Consequently, this review presents a comprehensive overview of the molecular microbiology tools and techniques that have played crucial roles in genetic studies of the bacteria found within the human oral microbiota. Here, we will use specific examples from the oral microbiome literature to illustrate the biology supporting these techniques, why they are needed in the field, and how such technologies have been implemented. It is hoped that this information can serve as a useful reference guide to help catalyze molecular microbiology studies of the many new understudied and uncharacterized species identified at different mucosal sites in the body.
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Affiliation(s)
- Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
| | - Jens Kreth
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
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Horch R, Rasp D, Dietz A, Ebbert R, Steinmann J, Schaible UE, Mamat U, Bertram R. tet-Dependent Gene Expression in Stenotrophomonas maltophilia. Microbiol Spectr 2023; 11:e0157623. [PMID: 37378537 PMCID: PMC10434252 DOI: 10.1128/spectrum.01576-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023] Open
Abstract
Stenotrophomonas maltophilia is increasingly recognized as an important nosocomial pathogen among the Gram-negative bacteria. Intrinsic resistance to different classes of antibiotics makes treatment of infections challenging. A deeper understanding of S. maltophilia physiology and virulence requires molecular genetic tools. Here, we describe the implementation of tetracycline-dependent gene regulation (tet regulation) in this bacterium. The exploited tet regulatory sequence of transposon Tn10 contained the tetR gene and three intertwined promoters, one of which was required for regulated expression of a target gene or operon. The episomal tet architecture was tested with a gfp variant as a quantifiable reporter. Fluorescence intensity was directly correlated with the concentration of the inducer anhydrotetracycline (ATc) applied and the duration of induction. Also, the expression of the rmlBACD operon of S. maltophilia K279a was subjected to tet control. These genes code for the synthesis of dTDP-l-rhamnose, an activated nucleotide sugar precursor of lipopolysaccharide (LPS) formation. A ΔrmlBACD mutant was complemented with a plasmid carrying this operon downstream of the tet sequence. In the presence of ATc, the LPS pattern was similar to that of wild-type S. maltophilia, whereas without the inducer, fewer and apparently shorter O-antigen chains were detected. This underscores the functionality and usefulness of the tet system for gene regulation and, prospectively, the validation of targets for new anti-S. maltophilia drugs. IMPORTANCE Stenotrophomonas maltophilia is an emerging pathogen in hospital settings and poses a threat to immunocompromised patients. Due to a high level of resistance to different types of antibiotics, treatment options are limited. We here adapted a tool for inducible expression of genes of interest, known as the tet system, to S. maltophilia. Genes relevant to producing surface carbohydrate structures (lipopolysaccharide [LPS]) were placed under the control of the tet system. In the presence of an inducer, the LPS pattern was similar to that of wild-type S. maltophilia, whereas in the "off" state of the system (without inducer), fewer and apparently shorter versions of LPS were detected. The tet system is functional in S. maltophilia and may be helpful to reveal gene-function relationships to gain a deeper understanding of the bacterium's physiology and virulence.
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Affiliation(s)
- Rebecca Horch
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Diana Rasp
- Study Program in Human Medicine, Paracelsus Medical University, Nuremberg, Germany
| | - Annika Dietz
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Ronald Ebbert
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Joerg Steinmann
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
| | - Ulrich E. Schaible
- Department of Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, Leibniz Research Alliance INFECTIONS, Borstel, Germany
| | - Uwe Mamat
- Department of Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, Leibniz Research Alliance INFECTIONS, Borstel, Germany
| | - Ralph Bertram
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
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Li H, Liu H, Qiu L, Xie Q, Chen B, Wang H, Long Y, Hu L, Fang C. Mechanism of antibiotic resistance development in an activated sludge system under tetracycline pressure. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:90844-90857. [PMID: 37464207 DOI: 10.1007/s11356-023-28744-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/07/2023] [Indexed: 07/20/2023]
Abstract
The mechanism of antibiotic resistance (AR) development in an activated sludge system under tetracycline (TC) pressure was discussed and analyzed. According to the variation of macro-factors, including TC, COD, TN, TP, NH3-N, pH, heavy metals, and reactor settings, the tet genes respond accordingly. Consequently, the enrichment sites of tet genes form an invisible AR selection zone, where AR microorganisms thrive, gather, reproduce, and spread. The efflux pump genes tetA and tetB prefer anaerobic environment, while ribosome protective protein genes tetM, tetO, tetQ, tetT, and tetW were more concentrated in aerobic situations. As a corresponding micro-effect, different types of tet genes selected the corresponding dominant bacteria such as Thauera and Arthrobacter, suggesting the intrinsic relationship between tet genes and potential hosts. In summary, the macro-response and micro-effect of tet genes constitute an interactive mechanism with tet genes as the core, which is the crucial cause for the continuous development of AR. This study provides an executable strategy to control the development of AR in actual wastewater treatment plants from the perspective of macro-factors and micro-effects.
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Affiliation(s)
- Hong Li
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China
| | - Hongyuan Liu
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China
| | - Libo Qiu
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China
| | - Qiaona Xie
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China
| | - Binhui Chen
- Key Laboratory of Recycling and Eco-Treatment of Waste Biomass of Zhejiang Province, Zhejiang University of Science and Technology, Hangzhou, 310023, China
| | - Hua Wang
- Key Laboratory of Recycling and Eco-Treatment of Waste Biomass of Zhejiang Province, Zhejiang University of Science and Technology, Hangzhou, 310023, China
| | - Yuyang Long
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Lifang Hu
- College of Quality and Safety Engineering, Institution of Industrial Carbon Metrology, China Jiliang University, Hangzhou, 310018, China
| | - Chengran Fang
- College of Civil Engineering, Zhejiang University of Technology, Hangzhou, 310023, China.
- Key Laboratory of Recycling and Eco-Treatment of Waste Biomass of Zhejiang Province, Zhejiang University of Science and Technology, Hangzhou, 310023, China.
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10
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Markakiou S, Neves AR, Zeidan AA, Gaspar P. Development of a Tetracycline-Inducible System for Conditional Gene Expression in Lactococcus lactis and Streptococcus thermophilus. Microbiol Spectr 2023; 11:e0066823. [PMID: 37191512 PMCID: PMC10269922 DOI: 10.1128/spectrum.00668-23] [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: 02/14/2023] [Accepted: 04/21/2023] [Indexed: 05/17/2023] Open
Abstract
Inducible gene expression systems are invaluable tools for the functional characterization of genes and in the construction of protein overexpression hosts. Controllable expression is especially important for the study of essential and toxic genes or genes where the level of expression tightly influences their cellular effect. Here, we implemented the well-characterized tetracycline-inducible expression system in two industrially important lactic acid bacteria, Lactococcus lactis and Streptococcus thermophilus. Using a fluorescent reporter gene, we show that optimization of the repression level is necessary for efficient induction using anhydrotetracycline in both organisms. Random mutagenesis in the ribosome binding site of the tetracycline repressor TetR in Lactococcus lactis indicated that altering the expression levels of TetR was necessary for efficient inducible expression of the reporter gene. Through this approach, we achieved plasmid-based, inducer-responsive, and tight gene expression in Lactococcus lactis. We then verified the functionality of the optimized inducible expression system in Streptococcus thermophilus following its chromosomal integration using a markerless mutagenesis approach and a novel DNA fragment assembly tool presented herein. This inducible expression system holds several advantages over other described systems in lactic acid bacteria, although more efficient techniques for genetic engineering are still needed to realize these advantages in industrially relevant species, such as S. thermophilus. Our work expands the molecular toolbox of these bacteria, which can accelerate future physiological studies. IMPORTANCE Lactococcus lactis and Streptococcus thermophilus are two industrially important lactic acid bacteria globally used in dairy fermentations and, therefore, are of considerable commercial interest to the food industry. Moreover, due to their general history of safe usage, these microorganisms are increasingly being explored as hosts for the production of heterologous proteins and various chemicals. Development of molecular tools in the form of inducible expression systems and mutagenesis techniques facilitates their in-depth physiological characterization as well as their exploitation in biotechnological applications.
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Affiliation(s)
- Sofia Markakiou
- R&D Department, Chr. Hansen A/S, Hørsholm, Denmark
- Department of Biochemistry, University of Groningen, Groningen, Netherlands
| | | | | | - Paula Gaspar
- R&D Department, Chr. Hansen A/S, Hørsholm, Denmark
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Xu SQ, Wang X, Xu L, Wang KX, Jiang YH, Zhang FY, Hong Q, He J, Liu SJ, Qiu JG. The MocR family transcriptional regulator DnfR has multiple binding sites and regulates Dirammox gene transcription in Alcaligenes faecalis JQ135. Environ Microbiol 2023; 25:675-688. [PMID: 36527381 DOI: 10.1111/1462-2920.16318] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
Microbial ammonia oxidation is vital to the nitrogen cycle. A biological process, called Dirammox (direct ammonia oxidation, NH3 →NH2 OH→N2 ), has been recently identified in Alcaligenes ammonioxydans and Alcaligenes faecalis. However, its transcriptional regulatory mechanism has not yet been fully elucidated. The present study characterized a new MocR-like transcription factor DnfR that is involved in the Dirammox process in A. faecalis strain JQ135. The entire dnf cluster was composed of 10 genes and transcribed as five transcriptional units, that is, dnfIH, dnfR, dnfG, dnfABCDE and dnfF. DnfR activates the transcription of dnfIH, dnfG and dnfABCDE genes, and represses its own transcription. The intact 1506-bp dnfR gene was required for activation of Dirammox. Electrophoretic mobility shift assays and DNase I footprinting analyses showed that DnfR has one binding site in the dnfH-dnfR intergenic region and two binding sites in the dnfG-dnfA intergenic region. Three binding sites of DnfR shared a 6-bp repeated conserved sequence 5'-GGTCTG-N17 -GGTCTG-3' which was essential for the transcription of downstream target genes. Cysteine and glutamate act as possible effectors of DnfR to activate the transcription of transcriptional units of dnfG and dnfABCDE, respectively. This study provided new insights in the transcriptional regulation mechanism of Dirammox by DnfR in A. faecalis JQ135.
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Affiliation(s)
- Si-Qiong Xu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Xiao Wang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Lu Xu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Ke-Xin Wang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Yin-Hu Jiang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Fu-Yin Zhang
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Qing Hong
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Jian He
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Resources, and Environmental Microbiology Research Center at Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ji-Guo Qiu
- Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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12
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Carrillo Rincón AF, Farny NG. Unlocking the strength of inducible promoters in Gram-negative bacteria. Microb Biotechnol 2023; 16:961-976. [PMID: 36738130 PMCID: PMC10128130 DOI: 10.1111/1751-7915.14219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 01/02/2023] [Accepted: 01/07/2023] [Indexed: 02/05/2023] Open
Abstract
Inducible bacterial promoters are ubiquitous biotechnology tools that have a consistent architecture including two key elements: the operator region recognized by the transcriptional regulatory proteins, and the -10 and -35 consensus sequences required to recruit the sigma (σ) 70 subunits of RNA polymerase to initiate transcription. Despite their widespread use, leaky transcription in the OFF state remains a challenge. We have updated the architecture of the lac and tet promoters to improve their strength, control and portability by the adaptation of the consensus -10 and -35 sequence boxes strongly targeted by σ70 , incorporation of a strong ribosome binding site recognized broadly by Gram-negative bacteria, and independent control of the transcriptional regulators by constitutive promoters. To test the promoters, we use the far-red fluorescent protein mCardinal, which significantly improves the signal-to-background ratio of promoter measurements over widely utilized green fluorescent proteins. We validate the improvement in OFF state control and inducibility by demonstrating production of the toxic and aggregate-prone cocaine esterase enzyme CocE. We further demonstrate portability of the promoters to additional Gram-negative species Pseudomonas putida and Vibrio natriegens. Our results represent a significant improvement over existing protein expression systems that will enable advances in protein production for various biotechnology applications.
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Affiliation(s)
| | - Natalie G Farny
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
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13
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Chen T, Zhao M, Tang X, Wang W, Zhang M, Tang J, Wang W, Wei W, Ma B, Zou Y, Zhang N, Mi J, Wang Y, Liao X, Wu Y. Serious Risk of Tigecycline Resistance in Escherichia coli Isolated from Swine Manure. MICROBIAL ECOLOGY 2022:10.1007/s00248-022-02133-2. [PMID: 36326874 DOI: 10.1007/s00248-022-02133-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
The emergence of the plasmid-mediated tigecycline resistance gene tetX family in pig farms has attracted worldwide attention. The use of tetracycline antibiotics in pig farms has a facilitating effect on the prevalence of the tetX family, but the relationship among its presence, expression, and resistance phenotype in resistant bacteria is unknown. In this study, the presence and expression characteristics of tetracycline resistance genes (TRGs) in 89 strains of doxycycline-resistant E. coli (DRE) isolated from pig manure samples from 20 pig farms under low concentrations of doxycycline stress (2 μg/mL) were analyzed. The detection rate of tetO was 96.63%, which is higher than those of other TRGs, such as tetA (94.38%), tetX (76.40%), tetB (73.03%), and tet(X4) (69.66%). At least three TRG types were present in DRE strains, which thus showed extensive resistance to tetracycline antibiotics, and 37% of these strains were resistant to tigecycline. In the presence of a low concentration of doxycycline, tetA played an important role, and the expression and existence ratio of TRGs indicated low expression of TRGs. Furthermore, the doxycycline resistance of DRE was jointly determined by the total absolute abundance of TRGs, and the absolute abundance of tetX and tet(X4) was significantly positively associated with tigecycline resistance in DRE (P < 0.05). Overall, DRE isolated from swine manure is an important reservoir of the tetX family, which suggests that DRE in swine manure has a high risk of tigecycline resistance, poses a potential threat to human health, and should be of public concern.
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Affiliation(s)
- Tao Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Minxing Zhao
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaoyue Tang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Wenqiang Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Miao Zhang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Jing Tang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Wei Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Wenxiao Wei
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
| | - Baohua Ma
- Foshan Customs Comprehensive Technology Center, 528200, Foshan, China
| | - Yongde Zou
- Foshan Customs Comprehensive Technology Center, 528200, Foshan, China
| | - Na Zhang
- Foshan Customs Comprehensive Technology Center, 528200, Foshan, China
| | - Jiandui Mi
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
- Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, 525000, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Engineering Technology Research Center of Harmless Treatment and Resource Utilization of Livestock Waste, Yunfu, Xinxing, China
- Ministry of Agriculture Key Laboratory of Tropical Agricultural Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Yan Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
- Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, 525000, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Engineering Technology Research Center of Harmless Treatment and Resource Utilization of Livestock Waste, Yunfu, Xinxing, China
- Ministry of Agriculture Key Laboratory of Tropical Agricultural Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Xindi Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China
- Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, 525000, China
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Engineering Technology Research Center of Harmless Treatment and Resource Utilization of Livestock Waste, Yunfu, Xinxing, China
- Ministry of Agriculture Key Laboratory of Tropical Agricultural Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Yinbao Wu
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, 510642, China.
- Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, 525000, China.
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China.
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Engineering Technology Research Center of Harmless Treatment and Resource Utilization of Livestock Waste, Yunfu, Xinxing, China.
- Ministry of Agriculture Key Laboratory of Tropical Agricultural Environment, South China Agricultural University, Guangzhou, 510642, China.
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14
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Fournier KC, Paquet VE, Attéré SA, Farley J, Marquis H, Gantelet H, Ravaille C, Vincent AT, Charette SJ. Expansion of the pRAS3 Plasmid Family in Aeromonas salmonicida subsp. salmonicida and Growing Evidence of Interspecies Connections for These Plasmids. Antibiotics (Basel) 2022; 11:antibiotics11081047. [PMID: 36009916 PMCID: PMC9405359 DOI: 10.3390/antibiotics11081047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/31/2022] [Accepted: 08/02/2022] [Indexed: 01/27/2023] Open
Abstract
Aeromonas salmonicida subsp. salmonicida is a pathogenic bacterium responsible for furunculosis in salmonids. Following an outbreak of furunculosis, the infection can be treated with antibiotics, but it is common to observe ineffective treatment due to antibiotic resistance. This bacterium has a wide variety of plasmids responsible for this resistance. Among them, pRAS3 carries a tetracycline resistance gene. Several variants of this plasmid have been discovered over the years (pRAS3-3432 and pRAS3.1 to 3.4). During the present study, two new variants of the plasmid pRAS3 were identified (pRAS3.5 and pRAS3-3759) in strains of A. salmonicida subsp. salmonicida. Plasmid pRAS3-3759, which has been found in many strains from the same region over the past three years, has an additional genetic element identical to one found in pRAS3-3432. This genetic element was also found in Chlamydia suis, a swine pathogen. In this study, we analyzed the bacteria’s resistance to tetracycline, the number of copies of the plasmids, and the growth of the strains that carry five of the pRAS3 variants (pRAS3.3 to 3.5, pRAS3-3432, and pRAS3-3759). The results show no particular trend despite the differences between the plasmids, except for the resistance to tetracycline when analyzed in an isogenic background. Blast analysis also revealed the presence of pRAS3 plasmids in other bacterial species, which suggests that this plasmid family has widely spread. This study once again highlights the ability of A. salmonicida subsp. salmonicida to adapt to furunculosis antibiotic treatments, and the still-growing family of pRAS3 plasmids.
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Affiliation(s)
- Kim C. Fournier
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada; (K.C.F.); (V.E.P.); (S.A.A.); (A.T.V.)
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Valérie E. Paquet
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada; (K.C.F.); (V.E.P.); (S.A.A.); (A.T.V.)
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
- Centre de Recherche de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ), Quebec City, QC G1V 4G5, Canada
| | - Sabrina A. Attéré
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada; (K.C.F.); (V.E.P.); (S.A.A.); (A.T.V.)
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Judith Farley
- Aquarium du Québec, Quebec City, QC G1W 4S3, Canada;
| | - Hélène Marquis
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA;
| | | | | | - Antony T. Vincent
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada; (K.C.F.); (V.E.P.); (S.A.A.); (A.T.V.)
- Département des Sciences Animales, Faculté des Sciences de L’agriculture et de L’alimentation, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Steve J. Charette
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec City, QC G1V 0A6, Canada; (K.C.F.); (V.E.P.); (S.A.A.); (A.T.V.)
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
- Centre de Recherche de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ), Quebec City, QC G1V 4G5, Canada
- Correspondence: ; Tel.: +1-418-656-2131 (ext. 406914)
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15
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Krause AL, Stinear TP, Monk IR. Barriers to genetic manipulation of Enterococci: Current Approaches and Future Directions. FEMS Microbiol Rev 2022; 46:6650352. [PMID: 35883217 PMCID: PMC9779914 DOI: 10.1093/femsre/fuac036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/14/2022] [Accepted: 07/22/2022] [Indexed: 01/09/2023] Open
Abstract
Enterococcus faecalis and Enterococcus faecium are Gram-positive commensal gut bacteria that can also cause fatal infections. To study clinically relevant multi-drug resistant E. faecalis and E. faecium strains, methods are needed to overcome physical (thick cell wall) and enzymatic barriers that limit the transfer of foreign DNA and thus prevent facile genetic manipulation. Enzymatic barriers to DNA uptake identified in E. faecalis and E. faecium include type I, II and IV restriction modification systems and CRISPR-Cas. This review examines E. faecalis and E. faecium DNA defence systems and the methods with potential to overcome these barriers. DNA defence system bypass will allow the application of innovative genetic techniques to expedite molecular-level understanding of these important, but somewhat neglected, pathogens.
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Affiliation(s)
- Alexandra L Krause
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection & Immunity, Melbourne, VIC 3000 Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection & Immunity, Melbourne, VIC 3000 Australia
| | - Ian R Monk
- Corresponding author: Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection & Immunity, Melbourne, VIC 3000 Australia. E-mail:
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