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Oles RE, Terrazas MC, Loomis LR, Neal MJ, Paulchakrabarti M, Zuffa S, Hsu CY, Vasquez Ayala A, Lee MH, Tribelhorn C, Belda-Ferre P, Bryant M, Zemlin J, Young J, Dulai P, Sandborn WJ, Sivagnanam M, Raffatellu M, Pride D, Dorrestein PC, Zengler K, Choudhury B, Knight R, Chu H. Pathogenic Bacteroides fragilis strains can emerge from gut-resident commensals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.19.599758. [PMID: 38948766 PMCID: PMC11213024 DOI: 10.1101/2024.06.19.599758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Bacteroides fragilis is a prominent member of the human gut microbiota, playing crucial roles in maintaining gut homeostasis and host health. Although it primarily functions as a beneficial commensal, B. fragilis can become pathogenic. To determine the genetic basis of its duality, we conducted a comparative genomic analysis of 813 B. fragilis strains, representing both commensal and pathogenic origins. Our findings reveal that pathogenic strains emerge across diverse phylogenetic lineages, due in part to rapid gene exchange and the adaptability of the accessory genome. We identified 16 phylogenetic groups, differentiated by genes associated with capsule composition, interspecies competition, and host interactions. A microbial genome-wide association study identified 44 genes linked to extra-intestinal survival and pathogenicity. These findings reveal how genomic diversity within commensal species can lead to the emergence of pathogenic traits, broadening our understanding of microbial evolution in the gut.
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Affiliation(s)
- Renee E. Oles
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | | | - Luke R. Loomis
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Maxwell J. Neal
- Department of Bioengineering, University of California, San Diego, La Jolla, CA
| | | | - Simone Zuffa
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA
| | - Chia-Yun Hsu
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | | | - Michael H. Lee
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - Caitlin Tribelhorn
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - Pedro Belda-Ferre
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - MacKenzie Bryant
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - Jasmine Zemlin
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA
| | - Jocelyn Young
- Division of Gastroenterology, Hepatology and Nutrition, University of California, San Diego and Rady Children’s Hospital, San Diego, CA
| | - Parambir Dulai
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA
- Division of Gastroenterology, Northwestern University, Chicago, Illinois
| | - William J. Sandborn
- Division of Gastroenterology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
| | - Mamata Sivagnanam
- Division of Gastroenterology, Hepatology and Nutrition, University of California, San Diego and Rady Children’s Hospital, San Diego, CA
| | - Manuela Raffatellu
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy and Vaccines (cMAV), University of California, San Diego, La Jolla, CA
| | - David Pride
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Center for Innovative Phage Applications and Therapeutics (IPATH), University of California, San Diego, La Jolla, CA
- Center of Advanced Laboratory Medicine (CALM), University of California, San Diego, La Jolla, CA
| | - Pieter C. Dorrestein
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA
| | - Karsten Zengler
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
- Department of Bioengineering, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Program in Materials Science and Engineering, University of California, San Diego, La Jolla, CA
| | - Biswa Choudhury
- GlycoAnalytics Core, University of California San Diego, San Diego, CA
| | - Rob Knight
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Shu Chien-Gene Lay Department of Bioengineering, University of California San Diego, La Jolla, CA
- Department of Computer Science & Engineering, University of California, San Diego, La Jolla, CA
- Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA
| | - Hiutung Chu
- Department of Pathology, University of California, San Diego, La Jolla, CA
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy and Vaccines (cMAV), University of California, San Diego, La Jolla, CA
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Freitas CFD, Carvalho LMVF, Camargo AC, Almeida OGGD, Oliveira RRD, De Martinis EP, Yamatogi RS, Nero LA. Bacterial microbiota shifts in vacuum-packed beef during storage at different temperatures: Impacts on blown pack spoilage. Food Microbiol 2024; 119:104448. [PMID: 38225050 DOI: 10.1016/j.fm.2023.104448] [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: 07/03/2023] [Revised: 11/21/2023] [Accepted: 12/06/2023] [Indexed: 01/17/2024]
Abstract
We aimed to evaluate the bacterial growth and diversity in vacuum-packed beef bags stored at different temperatures and to monitor blown-pack spoilage. We used culture-based methods and high-throughput sequencing to study the development of the main bacterial groups naturally present in beef stored at 4 and 15 °C for 28 days. The growth of sulfite-reducing clostridium (SRC) was impaired in beef bags stored at 4 °C; significant differences among SRC counts were observed in beef bags stored at 4 and 15 °C on days 14, 21, and 28 (P = 0.001). Blown pack was observed in most beef bags stored at 15 °C, from day 14 to day 28, but not in beef bags stored at 4 °C. A storage temperature of 4 °C was able to maintain a stable bacterial microbiota (most prevalent: Photobacterium, Hafnia-Obesumbacterium, and Lactococcus). Remarkable changes in microbial abundance occurred at 15 °C from day 14 to day 28, with a predominance of strict anaerobes (Bacteroides) and the presence of Clostridium spp. The relative frequencies of strict anaerobes and Clostridium were statistically higher in the beef bags stored at 15 °C (P < 0.001 and P = 0.004, respectively). The temperature influenced the microbial counts and relative abundance of spoilage bacteria, leading to blown pack spoilage.
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Affiliation(s)
- Caio Fialho de Freitas
- Universidade Federal de Viçosa, Departamento de Veterinária, Laboratório de Inspeção de Produtos de Origem Animal - InsPOA, Avenida PH Rolfs, s/n, Campus Universitário, 36570-900 Viçosa, MG, Brazil
| | - Lara Maria Vieira Flores Carvalho
- Universidade Federal de Viçosa, Departamento de Veterinária, Laboratório de Inspeção de Produtos de Origem Animal - InsPOA, Avenida PH Rolfs, s/n, Campus Universitário, 36570-900 Viçosa, MG, Brazil
| | - Anderson Carlos Camargo
- Universidade Federal de Viçosa, Departamento de Tecnologia de Alimentos, Avenida PH Rolfs, s/n, Campus Universitário, 36570-900 Viçosa, MG, Brazil
| | - Otávio Guilherme Gonçalves de Almeida
- Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Av. do Café s/n, Monte Alegre, 14040-903 Ribeirão Preto, SP, Brazil
| | - Rafael R de Oliveira
- Neoprospecta Microbiome Technologies, Av. Luiz Boiteux Piazza, 1302, Canasvieiras, 88056-000 Florianópolis, SC, Brazil
| | - Elaine Pereira De Martinis
- Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Av. do Café s/n, Monte Alegre, 14040-903 Ribeirão Preto, SP, Brazil
| | - Ricardo Seiti Yamatogi
- Universidade Federal de Viçosa, Departamento de Veterinária, Laboratório de Inspeção de Produtos de Origem Animal - InsPOA, Avenida PH Rolfs, s/n, Campus Universitário, 36570-900 Viçosa, MG, Brazil
| | - Luís Augusto Nero
- Universidade Federal de Viçosa, Departamento de Veterinária, Laboratório de Inspeção de Produtos de Origem Animal - InsPOA, Avenida PH Rolfs, s/n, Campus Universitário, 36570-900 Viçosa, MG, Brazil.
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Spigaglia P, Barbanti F, Germinario EAP, Criscuolo EM, Bruno G, Sanchez-Mete L, Porowska B, Stigliano V, Accarpio F, Oddi A, Zingale I, Rossi S, De Angelis R, Fabbri A. Comparison of microbiological profile of enterotoxigenic Bacteroides fragilis (ETBF) isolates from subjects with colorectal cancer (CRC) or intestinal pre-cancerous lesions versus healthy individuals and evaluation of environmental factors involved in intestinal dysbiosis. Anaerobe 2023; 82:102757. [PMID: 37380012 DOI: 10.1016/j.anaerobe.2023.102757] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 06/30/2023]
Abstract
OBJECTIVE The aim of this study was to analyze enterotoxigenic Bacteroides fragilis (ETBF) isolates from colorectal biopsies of subjects with a histological analysis positive for colorectal cancer (CRC), pre-cancerous lesions (pre-CRC) or with a healthy intestinal tissue and to evaluate the environmental factors that may not only concur to CRC development but may also affect gut microbiota composition. METHODS ETBF isolates were typed using the ERIC-PCR method, while PCR assays were performed to investigate the bft alleles, the B. fragilis pathogenicity island (BFPAI) region and the cepA, cfiA and cfxA genes. Susceptibility to antibiotics was tested using the agar dilution method. Environmental factors that could play a role in promoting intestinal dysbiosis were evaluated throughout a questionnaire administered to the subjects enrolled. RESULTS Six different ERIC-PCR types were identified. The type denominated C in this study was the most prevalent, in particular among the biopsies of subjects with pre-CRC, while an isolate belonging to a different type, denominated F, was detected in a biopsy from a subject with CRC. All the ETBF isolates from pre-CRC or CRC subjects had a B. fragilis pathogenicity island (BFPAI) region pattern I, while those from healthy individuals showed also different patterns. Furthermore, 71% of isolates from subjects with pre-CRC or CRC were resistant to two or more classes of antibiotics vs 43% of isolates from healthy individuals. The B. fragilis toxin BFT1 was the most frequently detected in this study, confirming the constant circulation of this isoform strains in Italy. Interestingly, BFT1 was found in 86% of the ETBF isolates from patients with CRC or pre-CRC, while the BFT2 was prevalent among the ETBF isolates from healthy subjects. No substantial differences based on sex, age, tobacco and alcohol consumption were observed between healthy and non-healthy individuals included in this study, while most of the subjects with CRC or pre-CRC lesions were subjected to pharmacological therapy (71%) and showed a body mass index (BMI) that falls within the overweight range (86%). CONCLUSIONS Our data suggest that some types of ETBF seem to better adapt and colonize the human gut and that the selective pressure exerted by factors related to lifestyle, such as pharmacological therapy and weight, could facilitate their persistence in the gut and their possible involvement in CRC development.
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Affiliation(s)
- Patrizia Spigaglia
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161, Rome, Italy.
| | - Fabrizio Barbanti
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161, Rome, Italy.
| | - Elena Angela Pia Germinario
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161, Rome, Italy.
| | | | - Giovanni Bruno
- Department of Translational and Precision Medicine, Gastroenterology Unit, Policlinic Umberto I, University of Rome 'Sapienza', 00161, Rome, Italy.
| | - Lupe Sanchez-Mete
- Gastroenterology and Digestive Endoscopy IRCCS Regina Elena National Cancer Institute, 00144, Rome, Italy.
| | - Barbara Porowska
- Digestive Endoscopy UOC CSC03 of the Department of General Surgery, Surgical Specialities "Paride Stefanini", Policlinic Umberto I, University of Rome 'Sapienza', 00161, Rome, Italy.
| | - Vittoria Stigliano
- Gastroenterology and Digestive Endoscopy IRCCS Regina Elena National Cancer Institute, 00144, Rome, Italy.
| | - Fabio Accarpio
- Digestive Endoscopy UOC CSC03 of the Department of General Surgery, Surgical Specialities "Paride Stefanini", Policlinic Umberto I, University of Rome 'Sapienza', 00161, Rome, Italy.
| | - Andrea Oddi
- Hepatopancreatobiliary Surgery, IRCCS Regina Elena National Cancer Institute, 00114, Rome, Italy.
| | - Ilaria Zingale
- Digestive Endoscopy UOC CSC03 of the Department of General Surgery, Surgical Specialities "Paride Stefanini", Policlinic Umberto I, University of Rome 'Sapienza', 00161, Rome, Italy.
| | - Silvia Rossi
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy.
| | - Roberta De Angelis
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy.
| | - Alessia Fabbri
- Department of Cardiovascular, Endocrine-Metabolic Diseases and Ageing, Istituto Superiore di Sanità, 00161, Rome, Italy.
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Jimenez‐Alesanco A, Eckhard U, Asencio del Rio M, Vega S, Guevara T, Velazquez‐Campoy A, Gomis‐Rüth FX, Abian O. Repositioning small molecule drugs as allosteric inhibitors of the BFT-3 toxin from enterotoxigenic Bacteroides fragilis. Protein Sci 2022; 31:e4427. [PMID: 36173175 PMCID: PMC9514063 DOI: 10.1002/pro.4427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/16/2022] [Accepted: 08/19/2022] [Indexed: 11/11/2022]
Abstract
Bacteroides fragilis is an abundant commensal component of the healthy human colon. However, under dysbiotic conditions, enterotoxigenic B. fragilis (ETBF) may arise and elicit diarrhea, anaerobic bacteremia, inflammatory bowel disease, and colorectal cancer. Most worrisome, ETBF is resistant to many disparate antibiotics. ETBF's only recognized specific virulence factor is a zinc-dependent metallopeptidase (MP) called B. fragilis toxin (BFT) or fragilysin, which damages the intestinal mucosa and triggers disease-related signaling mechanisms. Thus, therapeutic targeting of BFT is expected to limit ETBF pathogenicity and improve the prognosis for patients. We focused on one of the naturally occurring BFT isoforms, BFT-3, and managed to repurpose several approved drugs as BFT-3 inhibitors through a combination of biophysical, biochemical, structural, and cellular techniques. In contrast to canonical MP inhibitors, which target the active site of mature enzymes, these effectors bind to a distal allosteric site in the proBFT-3 zymogen structure, which stabilizes a partially unstructured, zinc-free enzyme conformation by shifting a zinc-dependent disorder-to-order equilibrium. This yields proBTF-3 incompetent for autoactivation, thus ablating hydrolytic activity of the mature toxin. Additionally, a similar destabilizing effect is observed for the activated protease according to biophysical and biochemical data. Our strategy paves a novel way for the development of highly specific inhibitors of ETBF-mediated enteropathogenic conditions.
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Affiliation(s)
- Ana Jimenez‐Alesanco
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC‐CSIC‐BIFIUniversidad de ZaragozaZaragozaSpain
- Departamento de Bioquímica y Biología Molecular y CelularUniversidad de ZaragozaZaragozaSpain
| | - Ulrich Eckhard
- Proteolysis Laboratory, Department of Structural BiologyMolecular Biology Institute of Barcelona (IBMB), Higher Scientific Research Council (CSIC)BarcelonaCataloniaSpain
| | - Marta Asencio del Rio
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC‐CSIC‐BIFIUniversidad de ZaragozaZaragozaSpain
- Instituto de Investigación Sanitaria de Aragón (IIS Aragon)ZaragozaSpain
| | - Sonia Vega
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC‐CSIC‐BIFIUniversidad de ZaragozaZaragozaSpain
| | - Tibisay Guevara
- Proteolysis Laboratory, Department of Structural BiologyMolecular Biology Institute of Barcelona (IBMB), Higher Scientific Research Council (CSIC)BarcelonaCataloniaSpain
| | - Adrian Velazquez‐Campoy
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC‐CSIC‐BIFIUniversidad de ZaragozaZaragozaSpain
- Departamento de Bioquímica y Biología Molecular y CelularUniversidad de ZaragozaZaragozaSpain
- Instituto de Investigación Sanitaria de Aragón (IIS Aragon)ZaragozaSpain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas Digestivas (CIBERehd)MadridSpain
| | - Francesc Xavier Gomis‐Rüth
- Proteolysis Laboratory, Department of Structural BiologyMolecular Biology Institute of Barcelona (IBMB), Higher Scientific Research Council (CSIC)BarcelonaCataloniaSpain
| | - Olga Abian
- Institute for Biocomputation and Physics of Complex Systems (BIFI), Joint Unit GBsC‐CSIC‐BIFIUniversidad de ZaragozaZaragozaSpain
- Departamento de Bioquímica y Biología Molecular y CelularUniversidad de ZaragozaZaragozaSpain
- Instituto de Investigación Sanitaria de Aragón (IIS Aragon)ZaragozaSpain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas Digestivas (CIBERehd)MadridSpain
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5
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Esteves E, Whyte P, Mills J, Brightwell G, Gupta TB, Bolton D. An investigation into the anaerobic spoilage microbiota of beef carcass and rump steak cuts using high- throughput sequencing. FEMS Microbiol Lett 2021; 368:6362601. [PMID: 34472614 DOI: 10.1093/femsle/fnab109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/31/2021] [Indexed: 11/14/2022] Open
Abstract
The presence of anaerobic microflora on fresh beef carcass and rump steaks, which may contribute to meat spoilage, was explored in this study. A total of 120 carcass and 120 rump steak swabs were collected immediately after slaughtering and boning, respectively from five meat plants, anaerobically incubated and enriched at 4°C for 3 weeks. This was followed by DNA extraction and 16S rRNA amplicon sequencing using the Illumina MiSeq, with subsequent bioinformatics analysis. The enriched microbiota of the samples was classified and grouped into 149 operational taxonomic units (OTUs). The microbiota recovered from both sample types consisted mainly of Carnobacterium, with an average relative abundance of 28.4% and 32.8% in beef carcasses and beef rump steaks, respectively. This was followed by Streptococcus, Serratia, Lactococcus, Enterococcus, Escherichia-Shigella, Raoultella and Aeromonas ranging from 1.5 to 20% and 0.1 to 29.8% in enriched carcasses and rump steak swabs, respectively. Trichococcus, Bacteroides, Dysgomonas, Providencia, Paraclostridium and Proteus were also present ranging from 0 to 0.8% on carcass and 0 to 1.8% on rump steak swabs, respectively. Alpha and beta diversity measurements showed limited diversity between the two sample types, but some differences between samples from the beef plants investigated were evident. This study highlights the presence of potential spoilage bacteria, mainly anaerobic genera on and between carcass and rump steaks, as an indication of contamination on and between these samples.
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Affiliation(s)
- Eden Esteves
- Department of Food Safety, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.,School of Veterinary Medicine, UCD, Belfield, Dublin 4, Ireland.,Food Assurance Team, AgResearch Limited, Hopkirk Research Institute, Massey University, Palmerston North 4472, New Zealand
| | - Paul Whyte
- School of Veterinary Medicine, UCD, Belfield, Dublin 4, Ireland
| | - John Mills
- Food Assurance Team, AgResearch Limited, Hopkirk Research Institute, Massey University, Palmerston North 4472, New Zealand
| | - Gale Brightwell
- Food Assurance Team, AgResearch Limited, Hopkirk Research Institute, Massey University, Palmerston North 4472, New Zealand
| | - Tanushree B Gupta
- Food Assurance Team, AgResearch Limited, Hopkirk Research Institute, Massey University, Palmerston North 4472, New Zealand
| | - Declan Bolton
- Department of Food Safety, Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland
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Sóki J, Keszőcze A, Nagy I, Burián K, Nagy E. An update on ampicillin resistance and β-lactamase genes of Bacteroides spp. J Med Microbiol 2021; 70. [PMID: 34463608 DOI: 10.1099/jmm.0.001393] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Introduction. There are several β-lactamase genes described for Bacteroides strains, of which cepA and cfiA are specific for Bacteroides fragilis and define two genetic divisions. The expression and phenotypic effects of these genes are usually regulated by insertional activation.Hypotheses/Gap Statement. Information is lacking about how cepA is regulated for most of the B. fragilis strains and whether there could be a genetic element for it.Aim. We aimed to investigate the molecular background of ampicillin (and other β-lactam) resistance among Bacteroides strains as mediated mainly by cepA and also to find a genetic element for it as known for cfiA.Methodology. Various PCR methods were used for β-lactamase-resistance gene and insertion sequence (IS) element detection in 42 Bacteroides strains. β-Lactamase activity measurements and antimicrobial-susceptibility testing using agar dilution were also applied. Further molecular experiments involved sequencing, gene targeting, Southern blotting and bioinformatic analyses.Results. We found that high antibiotic resistance and β-lactamase levels are brought about by insertional activation of the cepA gene or by similar or dissimilar activation of cfxA or cfiA, or by the newly described pbbA genes. Non-activated cepA genes produced low levels of specific β-lactamase activities that did not correlate with ampicillin resistance. We found a genetic element for cepA and another region close to it that are characteristic for division I B. fragilis strains, which are replaced by other sequences in division II B. fragilis strains.Conclusion. cepA usually is not activated by IS elements and usually produces low β-lactamase activities that do not correlate with the ampicillin MICs; therefore, it probably involves some non-β-lactamase-mediated resistance mechanism(s). pbpA is a newly described, effective β-lactamase gene that is located on a plasmid, and cepA resides on a well-defined chromosomal segment that is mutually replaced in division II B. fragilis strains. This latter finding demonstrates the genetic dichotomy of cepA-cfiA in B. fragilis and requires further investigation.
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Affiliation(s)
- József Sóki
- Institute of Medical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Anikó Keszőcze
- Institute of Medical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Present address: National Institute of Oncology, Budapest, Hungary
| | - István Nagy
- SEQOMICS Ltd., Mórahalom, Hungary.,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Katalin Burián
- Institute of Medical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisabeth Nagy
- Institute of Medical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary
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7
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Affiliation(s)
- Hannah C. Carrow
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
| | - Lakshmi E. Batachari
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
| | - Hiutung Chu
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy, and Vaccine, La Jolla, California, United States of America
- Humans and the Microbiome Program, CIFAR, Toronto, Ontario, Canada
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8
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Jasemi S, Emaneini M, Fazeli MS, Ahmadinejad Z, Nomanpour B, Sadeghpour Heravi F, Sechi LA, Feizabadi MM. Toxigenic and non-toxigenic patterns I, II and III and biofilm-forming ability in Bacteroides fragilis strains isolated from patients diagnosed with colorectal cancer. Gut Pathog 2020; 12:28. [PMID: 32518594 PMCID: PMC7273666 DOI: 10.1186/s13099-020-00366-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 05/30/2020] [Indexed: 12/12/2022] Open
Abstract
Background Enterotoxigenic Bacteroides fragilis (ETBF) associated with the initiation and progression of colorectal cancer (CRC) has been alarmingly reported all over the world. In this study, simultaneous investigation of toxigenic and non-toxigenic patterns I, II and III and biofilm formation ability of Bacteroides fragilis isolated from patients with colorectal cancer was performed. Methods Thirty-one patients diagnosed with CRC and thirty-one control subjects were recruited in this study. Specimens were cultured on BBE and BBA culture media. Classical phenotypic identification tests and PCR was performed to verify Bacteroides fragilis presence. Also, biofilm-forming ability and expression of bft gene were assessed under biofilm and planktonic forms. Results A total of 68 B.fragilis was isolated from all colorectal tissue, of which 13 isolates (19.1%) (11 isolates from CRC and 2 from normal tissue) were positive for bft gene. The abundance patterns of I, II and III were as follow in descending order; pattern I > pattern III > pattern II in CRC subjects and pattern II > pattern III > pattern I in normal tissues. Also, pattern I showed higher biofilm formation ability compared to other patterns. Toxin expression was significantly reduced in biofilm form comparing with planktonic form. Conclusions Based on our findings, there was a difference between the abundance of patterns I, II, and III and biofilm formation in isolates obtained from CRC and normal tissues. Biofilm formation ability and toxin encoding gene (bft) are two main virulence factors in B. fragilis pathogenicity which require more investigation to treat B. fragilis infections effectively.
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Affiliation(s)
- Seyedesomaye Jasemi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Emaneini
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Sadegh Fazeli
- Department of Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Ahmadinejad
- Department of Infectious Diseases, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Bizhan Nomanpour
- Department of Microbiology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Fatemah Sadeghpour Heravi
- Surgical Infection Research Group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Leonardo A Sechi
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Mohammad Mehdi Feizabadi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Department of Biomedical Sciences, University of Sassari, Sassari, Italy
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Valguarnera E, Wardenburg JB. Good Gone Bad: One Toxin Away From Disease for Bacteroides fragilis. J Mol Biol 2019; 432:765-785. [PMID: 31857085 DOI: 10.1016/j.jmb.2019.12.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 11/27/2019] [Accepted: 12/05/2019] [Indexed: 02/06/2023]
Abstract
The human gut is colonized by hundreds of trillions of microorganisms whose acquisition begins during early infancy. Species from the Bacteroides genus are ubiquitous commensals, comprising about thirty percent of the human gut microbiota. Bacteroides fragilis is one of the least abundant Bacteroides species, yet is the most common anaerobe isolated from extraintestinal infections in humans. A subset of B. fragilis strains carry a genetic element that encodes a metalloprotease enterotoxin named Bacteroides fragilis toxin, or BFT. Toxin-bearing strains, or Enterotoxigenic B. fragilis (ETBF) cause acute and chronic intestinal disease in children and adults. Despite this association with disease, around twenty percent of the human population appear to be asymptomatic carriers of ETBF. BFT damages the colonic epithelial barrier by inducing cleavage of the zonula adherens protein E-cadherin and initiating a cell signaling response characterized by inflammation and c-Myc-dependent pro-oncogenic hyperproliferation. As a consequence, mice harboring genetic mutations that predispose to colonic inflammation or tumor formation are uniquely susceptible to toxin-mediated injury. The recent observation of ETBF-bearing biofilms in colon biopsies from humans with colon cancer susceptibility loci strongly suggests that ETBF is a driver of colorectal cancer. This article will address ETBF biology from a host-pathobiont perspective, including clinical data, analysis of molecular mechanisms of disease, and the complex ecological context of the human gut.
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Affiliation(s)
- Ezequiel Valguarnera
- Department of Pediatrics, Washington University School of Medicine, 660 S. Euclid Ave. Box 8208, St. Louis, MO 63110
| | - Juliane Bubeck Wardenburg
- Department of Pediatrics, Washington University School of Medicine, 660 S. Euclid Ave. Box 8208, St. Louis, MO 63110.
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10
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Chan JL, Wu S, Geis AL, Chan GV, Gomes TAM, Beck SE, Wu X, Fan H, Tam AJ, Chung L, Ding H, Wang H, Pardoll DM, Housseau F, Sears CL. Non-toxigenic Bacteroides fragilis (NTBF) administration reduces bacteria-driven chronic colitis and tumor development independent of polysaccharide A. Mucosal Immunol 2019; 12:164-177. [PMID: 30279518 PMCID: PMC6510666 DOI: 10.1038/s41385-018-0085-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/01/2018] [Accepted: 08/16/2018] [Indexed: 02/07/2023]
Abstract
Polysaccharide A (PSA), an immunogenic capsular component of non-toxigenic Bacteroides fragilis (NTBF) strain NCTC 9343, is reported to promote mucosal immune development and suppress colitis. Contrastingly, enterotoxigenic Bacteroides fragilis (ETBF) is highly associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC), rapidly inducing IL-17-dependent murine colitis and tumorigenesis. In specific-pathogen-free (SPF) C57BL/6 wild-type (WT) and multiple intestinal neoplasia (MinApc716+/-) mice, we show that sequential treatment of the NTBF strain, 9343, followed by the ETBF strain, 86-5443-2-2 (86), diminished colitis and tumorigenesis. Mice treated simultaneously with 9343 and 86 exhibited both severe colitis and tumorigenesis. Abrogated disease severity in sequentially treated mice was attributed to 9343 strain dominance and decreased IL-17A, but 86 colonization prior to or simultaneous with 9343 mitigated the anti-inflammatory effect of 9343. Remarkably, 9343-mediated protection was independent of PSA, as sequentially treated mice receiving ΔPSA 9343 exhibited similar protection. Further, SPF WT and Min mice colonized with PSA-competent or PSA-deficient 9343 exhibited similar IL-10, IL-17, and IFN-γ responses. Treatment of 86-colonized mice with 9343 failed to disrupt 86 pathogenesis. Our findings demonstrate that 9343 colonization, independent of PSA, offers prophylaxis against colitis-inducing 86 but may not be a valid therapy once colitis is established.
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Affiliation(s)
- June L Chan
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shaoguang Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Abby L Geis
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Department of Microbiology and Immunology, Arkansas College of Osteopathic Medicine, Fort Smith, Arkansas, USA
| | - Gabrielle V Chan
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Talles A M Gomes
- Medical School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Sarah E Beck
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinqun Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hongni Fan
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ada J Tam
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liam Chung
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Translational Tissue Engineering Center, Wilmer Eye Institute and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Hua Ding
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hao Wang
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Drew M Pardoll
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Franck Housseau
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Cynthia L Sears
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA.
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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11
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Chen S, Blom J, Loch TP, Faisal M, Walker ED. The Emerging Fish Pathogen Flavobacterium spartansii Isolated from Chinook Salmon: Comparative Genome Analysis and Molecular Manipulation. Front Microbiol 2017; 8:2339. [PMID: 29250046 PMCID: PMC5714932 DOI: 10.3389/fmicb.2017.02339] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/13/2017] [Indexed: 01/29/2023] Open
Abstract
Flavobacterium spartansii strain T16T was isolated from a disease outbreak in hatchery-reared Chinook salmon (Oncorhynchus tshawytscha) fingerlings. To gain insight into its genomic content, structure and virulence pathogenesis factors, comparative genome analyses were performed using genomes from environmental and virulent Flavobacterium strains. F. spartansii shared low average nucleotide identity (ANI) to well-known fish-pathogenic flavobacteria (e.g., F. columnare, F. psychrophilum, and F. branchiophilum), indicating that it is a new and emerging fish pathogen. The genome in T16T had a length of 5,359,952 bp, a GC-content 35.7%, and 4,422 predicted protein-coding sequences. Flavobacterium core genome analysis showed that the number of shared genes decreased with the addition of input genomes and converged at 1182 genes. At least 8 genomic islands and 5 prophages were predicted in T16T. At least 133 virulence factors associated with virulence in pathogenic bacteria were highly conserved in F. spartansii T16T. Furthermore, genes linked to virulence in other bacterial species (e.g., those encoding for a type IX secretion system, collagenase and hemolysin) were found in the genome of F. spartansii T16T and were conserved in most of the analyzed pathogenic Flavobacterium. F. spartansii was resistant to ampicillin and penicillin, consistent with the presence of multiple genes encoding diverse lactamases and the penicillin-binding protein in the genome. To allow for future investigations into F. spartansii virulence in vivo, a transposon-based random mutagenesis strategy was attempted in F. spartansii T16T using pHimarEm1. Four putative gliding motility deficient mutants were obtained and the insertion sites of pHimarEm1 in the genome of these mutants were characterized. In total, study results clarify some of the mechanisms by which emerging flavobacterial fish pathogens may cause disease and also provide direly needed tools to investigate their pathogenesis.
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Affiliation(s)
- Shicheng Chen
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University, Giessen, Germany
| | - Thomas P Loch
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
| | - Mohamed Faisal
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States.,Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
| | - Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
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12
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Genomic Diversity of Enterotoxigenic Strains of Bacteroides fragilis. PLoS One 2016; 11:e0158171. [PMID: 27348220 PMCID: PMC4922554 DOI: 10.1371/journal.pone.0158171] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/10/2016] [Indexed: 12/12/2022] Open
Abstract
Enterotoxigenic (ETBF) strains of Bacteroides fragilis are the subset of strains that secrete a toxin called fragilysin (Bft). Although ETBF strains are known to cause diarrheal disease and have recently been associated with colorectal cancer, they have not been well characterized. By sequencing the complete genome of four ETBF strains, we found that these strains exhibit considerable variation at the genomic level. Only a small number of genes that are located primarily in the Bft pathogenicity island (BFT PAI) and the flanking CTn86 conjugative transposon are conserved in all four strains and a fifth strain whose genome was previously sequenced. Interestingly, phylogenetic analysis strongly suggests that the BFT PAI was acquired by non-toxigenic (NTBF) strains multiple times during the course of evolution. At the phenotypic level, we found that the ETBF strains were less fit than the NTBF strain NCTC 9343 and were susceptible to a growth-inhibitory protein that it produces. The ETBF strains also showed a greater tendency to form biofilms, which may promote tumor formation, than NTBF strains. Although the genomic diversity of ETBF strains raises the possibility that they vary in their pathogenicity, our experimental results also suggest that they share common properties that are conferred by different combinations of non-universal genetic elements.
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Visweswariah SS, Busby SJW. Evolution of bacterial transcription factors: how proteins take on new tasks, but do not always stop doing the old ones. Trends Microbiol 2015; 23:463-7. [PMID: 26003748 DOI: 10.1016/j.tim.2015.04.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/11/2015] [Accepted: 04/24/2015] [Indexed: 11/16/2022]
Abstract
Many bacterial transcription factors do not behave as per the textbook operon model. We draw on whole genome work, as well as reported diversity across different bacteria, to argue that transcription factors may have evolved from nucleoid-associated proteins. This view would explain a large amount of recent data gleaned from high-throughput sequencing and bioinformatic analyses.
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Affiliation(s)
- Sandhya S Visweswariah
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
| | - Stephen J W Busby
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK.
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14
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Identification of antimicrobial resistance genes in multidrug-resistant clinical Bacteroides fragilis isolates by whole genome shotgun sequencing. Anaerobe 2015; 31:59-64. [DOI: 10.1016/j.anaerobe.2014.10.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/29/2014] [Accepted: 10/31/2014] [Indexed: 11/22/2022]
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15
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Shiryaev SA, Remacle AG, Cieplak P, Strongin AY. Peptide Sequence Region That is Essential for the Interactions of the Enterotoxigenic Bacteroides fragilis Metalloproteinase II with E-cadherin. JOURNAL OF PROTEOLYSIS 2014; 1:3-14. [PMID: 25964952 PMCID: PMC4425422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bacteroides fragilis is a valuable anaerobic commensal and an essential component of the gut microbiome in humans. The presence of a short pathogenicity island in the genome is predominantly associated with the enterotoxigenic strains of B. fragilis. Metallopro-teinase II (MPII) and fragilysin (FRA) are the structurally related enzymes encoded by the pathogenicity island in the enterotoxigenic strains. Accordingly, there is a significant overlap between the cleavage preferences of MPII and FRA. These proteinases, however, are counter-transcribed in the bacterial genome suggesting their distinct and specialized functions in the course of infection. It is well established that FRA directly cleaves E-cadherin, a key protein of the cell-to-cell adhesion junctions in the intestinal epithelium. Counterintuitively, MPII directly binds to, rather than cleaves, E-cadherin. Structural modeling suggested that a potential E-cadherin binding site involves the C-terminal -helical region of the MPII catalytic domain. The sequence of this region is different in MPII and FRA. Here, we employed substitution mutagenesis of this C-terminal -helical region to isolate the MPII mutants with the potentially inactivated E-cadherin binding site. Overall, as a result of our modeling, mutagenesis and binding studies, we determined that the C-terminal ten residue segment is essential for the binding of MPII, but not of FRA3, to E-cadherin, and that the resulting MPII•E-cadherin complex does not impair E-cadherin-dependent cell-to-cell contacts. It is possible to envision that the putative cleavage targets of MPII should be explored not only on the host cell surface but also in B. fragilis.
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Affiliation(s)
- Sergey A. Shiryaev
- To whom correspondence should be addressed: , tel: 858-795-5271, fax: 858-795-5225
| | - Albert G. Remacle
- To whom correspondence should be addressed: , tel: 858-795-5271, fax: 858-795-5225
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Huang K, Zhang XX, Shi P, Wu B, Ren H. A comprehensive insight into bacterial virulence in drinking water using 454 pyrosequencing and Illumina high-throughput sequencing. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 109:15-21. [PMID: 25129220 DOI: 10.1016/j.ecoenv.2014.07.029] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 07/20/2014] [Accepted: 07/24/2014] [Indexed: 06/03/2023]
Abstract
In order to comprehensively investigate bacterial virulence in drinking water, 454 pyrosequencing and Illumina high-throughput sequencing were used to detect potential pathogenic bacteria and virulence factors (VFs) in a full-scale drinking water treatment and distribution system. 16S rRNA gene pyrosequencing revealed high bacterial diversity in the drinking water (441-586 operational taxonomic units). Bacterial diversity decreased after chlorine disinfection, but increased after pipeline distribution. α-Proteobacteria was the most dominant taxonomic class. Alignment against the established pathogen database showed that several types of putative pathogens were present in the drinking water and Pseudomonas aeruginosa had the highest abundance (over 11‰ of total sequencing reads). Many pathogens disappeared after chlorine disinfection, but P. aeruginosa and Leptospira interrogans were still detected in the tap water. High-throughput sequencing revealed prevalence of various pathogenicity islands and virulence proteins in the drinking water, and translocases, transposons, Clp proteases and flagellar motor switch proteins were the predominant VFs. Both diversity and abundance of the detectable VFs increased after the chlorination, and decreased after the pipeline distribution. This study indicates that joint use of 454 pyrosequencing and Illumina sequencing can comprehensively characterize environmental pathogenesis, and several types of putative pathogens and various VFs are prevalent in drinking water.
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Affiliation(s)
- Kailong Huang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, 163 Xianlin Road, Nanjing 210023, China
| | - Xu-Xiang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, 163 Xianlin Road, Nanjing 210023, China.
| | - Peng Shi
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, 163 Xianlin Road, Nanjing 210023, China
| | - Bing Wu
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, 163 Xianlin Road, Nanjing 210023, China
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, 163 Xianlin Road, Nanjing 210023, China.
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Abstract
UNLABELLED The genome sequences of intestinal Bacteroidales strains reveal evidence of extensive horizontal gene transfer. In vitro studies of Bacteroides and other bacteria have addressed mechanisms of conjugative transfer and some phenotypic outcomes of these DNA acquisitions in the recipient, such as the acquisition of antibiotic resistance. However, few studies have addressed the horizontal transfer of genetic elements between bacterial species coresident in natural microbial communities, especially microbial ecosystems of humans. Here, we examine the genomes of Bacteroidales species from two human adults to identify genetic elements that were likely transferred among these Bacteroidales while they were coresident in the intestine. Using seven coresident Bacteroidales species from one individual and eight from another, we identified five large chromosomal regions, each present in a minimum of three of the coresident strains at near 100% DNA identity. These five regions are not found in any other sequenced Bacteroidetes genome at this level of identity and are likely all integrative conjugative elements (ICEs). Such highly similar and unique regions occur in only 0.4% of phylogenetically representative mock communities, providing strong evidence that these five regions were transferred between coresident strains in these subjects. In addition to the requisite proteins necessary for transfer, these elements encode proteins predicted to increase fitness, including orphan DNA methylases that may alter gene expression, fimbriae synthesis proteins that may facilitate attachment and the utilization of new substrates, putative secreted antimicrobial molecules, and a predicted type VI secretion system (T6SS), which may confer a competitive ecological advantage to these strains in their complex microbial ecosystem. IMPORTANCE By analyzing Bacteroidales strains coresident in the gut microbiota of two human adults, we provide strong evidence for extensive interspecies and interfamily transfer of integrative conjugative elements within the intestinal microbiota of individual humans. In the recipient strain, we show that the conjugative elements themselves can be modified by the transposition of insertion sequences and retroelements from the recipient's genome, with subsequent transfer of these modified elements to other members of the microbiota. These data suggest that the genomes of our gut bacteria are substantially modified by other, coresident members of the ecosystem, resulting in highly personalized Bacteroidales strains likely unique to that individual. The genetic content of these ICEs suggests that their transfer from successful adapted members of an ecosystem confers beneficial properties to the recipient, increasing its fitness and allowing it to better compete within its particular personalized gut microbial ecosystem.
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Shiryaev SA, Aleshin AE, Muranaka N, Kukreja M, Routenberg DA, Remacle AG, Liddington RC, Cieplak P, Kozlov IA, Strongin AY. Structural and functional diversity of metalloproteinases encoded by the Bacteroides fragilis pathogenicity island. FEBS J 2014; 281:2487-502. [PMID: 24698179 DOI: 10.1111/febs.12804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 01/04/2023]
Abstract
Bacteroides fragilis causes the majority of anaerobic infections in humans. The presence of a pathogenicity island in the genome discriminates pathogenic and commensal B. fragilis strains. The island encodes metalloproteinase II (MPII), a potential virulence protein, and one of three homologous fragilysin isozymes (FRA; also termed B. fragilis toxin or BFT). Here, we report biochemical data on the structural-functional characteristics of the B. fragilis pathogenicity island proteases by reporting the crystal structure of MPII at 2.13 Å resolution, combined with detailed characterization of the cleavage preferences of MPII and FRA3 (as a representative of the FRA isoforms), identified using a high-throughput peptide cleavage assay with 18 583 substrate peptides. We suggest that the evolution of the MPII catalytic domain can be traced to human and archaebacterial proteinases, whereas the prodomain fold is a feature specific to MPII and FRA. We conclude that the catalytic domain of both MPII and FRA3 evolved differently relative to the prodomain, and that the prodomain evolved specifically to fit the B. fragilis pathogenicity. Overall, our data provide insights into the evolution of cleavage specificity and activation mechanisms in the virulent metalloproteinases.
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Guglielmini J, Néron B, Abby SS, Garcillán-Barcia MP, de la Cruz F, Rocha EPC. Key components of the eight classes of type IV secretion systems involved in bacterial conjugation or protein secretion. Nucleic Acids Res 2014; 42:5715-27. [PMID: 24623814 PMCID: PMC4027160 DOI: 10.1093/nar/gku194] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Conjugation of DNA through a type IV secretion system (T4SS) drives horizontal gene transfer. Yet little is known on the diversity of these nanomachines. We previously found that T4SS can be divided in eight classes based on the phylogeny of the only ubiquitous protein of T4SS (VirB4). Here, we use an ab initio approach to identify protein families systematically and specifically associated with VirB4 in each class. We built profiles for these proteins and used them to scan 2262 genomes for the presence of T4SS. Our analysis led to the identification of thousands of occurrences of 116 protein families for a total of 1623 T4SS. Importantly, we could identify almost always in our profiles the essential genes of well-studied T4SS. This allowed us to build a database with the largest number of T4SS described to date. Using profile–profile alignments, we reveal many new cases of homology between components of distant classes of T4SS. We mapped these similarities on the T4SS phylogenetic tree and thus obtained the patterns of acquisition and loss of these protein families in the history of T4SS. The identification of the key VirB4-associated proteins paves the way toward experimental analysis of poorly characterized T4SS classes.
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Affiliation(s)
- Julien Guglielmini
- Microbial Evolutionary Genomics, Institut Pasteur, Paris 75015, France UMR3525, CNRS, Paris 75015, France
| | - Bertrand Néron
- Centre d'Informatique pour les Biologistes, Institut Pasteur, Paris 75015, France
| | - Sophie S Abby
- Microbial Evolutionary Genomics, Institut Pasteur, Paris 75015, France UMR3525, CNRS, Paris 75015, France
| | - María Pilar Garcillán-Barcia
- Institute of Biomedicine and Biotechnology of Cantabria (CSIC-Sodercan-University of Cantabria), Santander 39011, Spain
| | - Fernando de la Cruz
- Institute of Biomedicine and Biotechnology of Cantabria (CSIC-Sodercan-University of Cantabria), Santander 39011, Spain
| | - Eduardo P C Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, Paris 75015, France UMR3525, CNRS, Paris 75015, France
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Shiryaev SA, Remacle AG, Chernov AV, Golubkov VS, Motamedchaboki K, Muranaka N, Dambacher CM, Capek P, Kukreja M, Kozlov IA, Perucho M, Cieplak P, Strongin AY. Substrate cleavage profiling suggests a distinct function of Bacteroides fragilis metalloproteinases (fragilysin and metalloproteinase II) at the microbiome-inflammation-cancer interface. J Biol Chem 2013; 288:34956-67. [PMID: 24145028 DOI: 10.1074/jbc.m113.516153] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Enterotoxigenic anaerobic Bacteroides fragilis is a significant source of inflammatory diarrheal disease and a risk factor for colorectal cancer. Two distinct metalloproteinase types (the homologous 1, 2, and 3 isoforms of fragilysin (FRA1, FRA2, and FRA3, respectively) and metalloproteinase II (MPII)) are encoded by the B. fragilis pathogenicity island. FRA was demonstrated to be important to pathogenesis, whereas MPII, also a potential virulence protein, remained completely uncharacterized. Here, we, for the first time, extensively characterized MPII in comparison with FRA3, a representative of the FRA isoforms. We employed a series of multiplexed peptide cleavage assays to determine substrate specificity and proteolytic characteristics of MPII and FRA. These results enabled implementation of an efficient assay of MPII activity using a fluorescence-quenched peptide and contributed to structural evidence for the distinct substrate cleavage preferences of MPII and FRA. Our data imply that MPII specificity mimics the dibasic Arg↓Arg cleavage motif of furin-like proprotein convertases, whereas the cleavage motif of FRA (Pro-X-X-Leu-(Arg/Ala/Leu)↓) resembles that of human matrix metalloproteinases. To the best of our knowledge, MPII is the first zinc metalloproteinase with the dibasic cleavage preferences, suggesting a high level of versatility of metalloproteinase proteolysis. Based on these data, we now suggest that the combined (rather than individual) activity of MPII and FRA is required for the overall B. fragilis virulence in vivo.
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Affiliation(s)
- Sergey A Shiryaev
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037 and
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Sóki J, Eitel Z, Terhes G, Nagy E, Urbán E. Occurrence and analysis of rare cfiA–bft doubly positive Bacteroides fragilis strains. Anaerobe 2013; 23:70-3. [DOI: 10.1016/j.anaerobe.2013.06.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 06/07/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
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Abstract
The human colon plays host to a diverse and metabolically complex community of microorganisms. While the colonic microbiome has been suggested to contribute to the development of colorectal cancer (CRC), a definitive link has not been made. The role in which the colon microflora could contribute to the initiation and/or progression of CRC is explored in this review. Potential mechanisms of bacterial oncogenesis are presented, along with lines of evidence derived from animal models of microbially induced CRC. Particular focus is given to the oncogenic capabilities of enterotoxigenic Bacteroides fragilis. Recent progress in defining the microbiome of CRC in the human population is evaluated, and the future challenges of linking specific etiologic agents to CRC are emphasized.
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Affiliation(s)
- Christine Dejea
- Department of Molecular Microbiology & Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
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Trudel MV, Tanaka KH, Filion G, Daher RK, Frenette M, Charette SJ. Insertion sequence AS5 (IS AS5 ) is involved in the genomic plasticity of Aeromonas salmonicida.. Mob Genet Elements 2013; 3:e25640. [PMID: 23956951 PMCID: PMC3742599 DOI: 10.4161/mge.25640] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/02/2013] [Accepted: 07/05/2013] [Indexed: 12/16/2022] Open
Abstract
The genome of the fish pathogen Aeromonas salmonicida subsp salmonicida harbors a large number of insertion sequences (ISs), many of which are located on plasmids. In the present study, we analyzed the small plasmid profile of A. salmonicida strains to identify evidences of plasmid alterations. Ten out of 78 strains analyzed displayed an unconventional plasmid profile. However the HER1104 strain was unique, having a positive PCR signal for pAsal1 plasmid despite not carrying this plasmid. Instead, HER1104 was bearing a plasmid at higher molecular weight than pAsal1. We characterized this new larger plasmid, which we called pAsal1B since it is a derivative of pAsal1 containing one more complete IS (ISAS5) than the parental plasmid. An additional 96 bp relic of ISAS5 was also present in pAsal1B. These results propose that ISAS5 is another active mobile genetic element in A. salmonicida subsp salmonicida and provided further proof of the genomic plasticity of this bacterium.
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Affiliation(s)
- Mélanie V Trudel
- Institut de Biologie Intégrative et des Systèmes (IBIS); Pavillon Charles-Eugène-Marchand; Université Laval; Quebec City, QC Canada ; Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec; Quebec City, QC Canada
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Sóki J. Extended role for insertion sequence elements in the antibiotic resistance of Bacteroides. World J Clin Infect Dis 2013; 3:1-12. [DOI: 10.5495/wjcid.v3.i1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 12/04/2012] [Accepted: 12/17/2012] [Indexed: 02/06/2023] Open
Abstract
The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence (IS) elements, which are usually regarded as representatives of ‘selfish’ genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cepA (penicillin and cephalosporin), cfxA (cephamycin), cfiA (carbapenem), nim (metronidazole) and ermF (clindamycin) resistance genes. This is achieved by outward-oriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of the antibiotic resistance mechanisms of Bacteroides, which will have clinical implications.
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First report of the multidrug resistance gene cfr in Enterococcus faecalis of animal origin. Antimicrob Agents Chemother 2011; 56:1650-4. [PMID: 22203597 DOI: 10.1128/aac.06091-11] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The multiresistance gene cfr was identified for the first time in an Enterococcus faecalis isolate of animal origin. The 32,388-bp plasmid pEF-01, which carried the cfr gene, was sequenced completely. Three copies of the insertion sequence IS1216 were identified in pEF-01, and the detection of a cfr- and IS1216-containing amplicon by inverse PCR suggests that IS1216 may play a role in the dissemination of cfr by a recombination process.
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Schneider G, Dobrindt U, Middendorf B, Hochhut B, Szijártó V, Emody L, Hacker J. Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic Escherichia coli in vitro support the role of conjugation for horizontal transfer of genomic islands. BMC Microbiol 2011; 11:210. [PMID: 21943043 PMCID: PMC3202238 DOI: 10.1186/1471-2180-11-210] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 09/24/2011] [Indexed: 12/14/2022] Open
Abstract
Background A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs) - including pathogenicity islands (PAIs) - in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial) islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT). Transfer events of archetypal large genomic islands of enterobacteria which often lack genes required for mobilisation or transfer have been rarely investigated so far. Results To study mobilisation of such large genomic regions in prototypic uropathogenic E. coli (UPEC) strain 536, PAI II536 was supplemented with the mobRP4 region, an origin of replication (oriVR6K), an origin of transfer (oriTRP4) and a chloramphenicol resistance selection marker. In the presence of helper plasmid RP4, conjugative transfer of the 107-kb PAI II536 construct occured from strain 536 into an E. coli K-12 recipient. In transconjugants, PAI II536 existed either as a cytoplasmic circular intermediate (CI) or integrated site-specifically into the recipient's chromosome at the leuX tRNA gene. This locus is the chromosomal integration site of PAI II536 in UPEC strain 536. From the E. coli K-12 recipient, the chromosomal PAI II536 construct as well as the CIs could be successfully remobilised and inserted into leuX in a PAI II536 deletion mutant of E. coli 536. Conclusions Our results corroborate that mobilisation and conjugal transfer may contribute to evolution of bacterial pathogens through horizontal transfer of large chromosomal regions such as PAIs. Stabilisation of these mobile genetic elements in the bacterial chromosome result from selective loss of mobilisation and transfer functions of genomic islands.
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Affiliation(s)
- György Schneider
- Institute for Molecular Infection Biology, University of Würzburg, Josef-Schneider-Str, 2/Building D15, Würzburg, 97070, Germany
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Enterotoxigenic Bacteroides fragilis: a rogue among symbiotes. Clin Microbiol Rev 2009; 22:349-69, Table of Contents. [PMID: 19366918 DOI: 10.1128/cmr.00053-08] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Enterotoxigenic Bacteroides fragilis (ETBF) strains are strains of B. fragilis that secrete a 20-kDa heat-labile zinc-dependent metalloprotease toxin termed the B. fragilis toxin (BFT). BFT is the only recognized virulence factor specific for ETBF. ETBF strains are associated with inflammatory diarrheal disease in children older than 1 year of age and in adults; limited data suggest an association of ETBF colonization with inflammatory bowel disease flare-ups and colorectal cancer. ETBF secretes one of three highly related BFT isoforms. The relationship between BFT isoform and disease expression is unknown. Although the mechanism of action of BFT is incompletely understood, available data suggest that BFT binds to a specific intestinal epithelial cell receptor, stimulating intestinal cell signal transduction pathways that result in cell morphology changes, cleavage of E-cadherin, reduced colonic barrier function, and increased epithelial cell proliferation and cytokine expression (such as the proinflammatory chemokine interleukin-8). Together, the data suggest that in some hosts, ETBF acts via secretion of BFT to induce colitis. However, the full spectrum of clinical disease related to ETBF and the impact of chronic ETBF colonization on the host remain to be defined.
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Miranda KR, Dias MF, Guimarães PLS, Boente RF, Pauer H, Ramos PZ, Falcão LS, Ferreira EDO, Balassiano IT, Ferreira LQ, Santos-Filho JD, Paula GRD, Antunes ENF, Avelar KES, Domingues RMCP. Enterotoxigenic and nontoxigenic Bacteroides fragilis strains isolated in Brazil. Mem Inst Oswaldo Cruz 2009; 103:734-5. [PMID: 19057827 DOI: 10.1590/s0074-02762008000700018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 09/26/2008] [Indexed: 11/22/2022] Open
Abstract
The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.9% of the total analyzed strains, harbored the bft gene which was identified as bft-1 isoform based on PCR-RFLP and sequencing. Forty-nine strains (44.9%) exhibited the NTBF pattern III which possesses the flanking region required for pathogenicity island acquisition in which the bft gene is codified. These data reinforce the potential of B. fragilis as an emerging enteropathogen in our country.
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Affiliation(s)
- Karla R Miranda
- Laboratório de Biologia de Anaeróbios, Departamento de Microbiologia Médica, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
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Heather Z, Holden MTG, Steward KF, Parkhill J, Song L, Challis GL, Robinson C, Davis-Poynter N, Waller AS. A novel streptococcal integrative conjugative element involved in iron acquisition. Mol Microbiol 2009; 70:1274-92. [PMID: 18990191 PMCID: PMC3672683 DOI: 10.1111/j.1365-2958.2008.06481.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In this study, we determined the function of a novel non-ribosomal peptide synthetase (NRPS) system carried by a streptococcal integrative conjugative element (ICE), ICESe2. The NRPS shares similarity with the yersiniabactin system found in the high-pathogenicity island of Yersinia sp. and is the first of its kind to be identified in streptococci. We named the NRPS product 'equibactin' and genes of this locus eqbA-N. ICESe2, although absolutely conserved in Streptococcus equi, the causative agent of equine strangles, was absent from all strains of the closely related opportunistic pathogen Streptococcus zooepidemicus. Binding of EqbA, a DtxR-like regulator, to the eqbB promoter was increased in the presence of cations. Deletion of eqbA resulted in a small-colony phenotype. Further deletion of the irp2 homologue eqbE, or the genes eqbH, eqbI and eqbJ encoding a putative ABC transporter, or addition of the iron chelator nitrilotriacetate, reversed this phenotype, implicating iron toxicity. Quantification of (55)Fe accumulation and sensitivity to streptonigrin suggested that equibactin is secreted by S. equi and that the eqbH, eqbI and eqbJ genes are required for its associated iron import. In agreement with a structure-based model of equibactin synthesis, supplementation of chemically defined media with salicylate was required for equibactin production.
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Affiliation(s)
- Zoe Heather
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, UK
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Juhas M, van der Meer JR, Gaillard M, Harding RM, Hood DW, Crook DW. Genomic islands: tools of bacterial horizontal gene transfer and evolution. FEMS Microbiol Rev 2008; 33:376-93. [PMID: 19178566 PMCID: PMC2704930 DOI: 10.1111/j.1574-6976.2008.00136.x] [Citation(s) in RCA: 587] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bacterial genomes evolve through mutations, rearrangements or horizontal gene transfer. Besides the core genes encoding essential metabolic functions, bacterial genomes also harbour a number of accessory genes acquired by horizontal gene transfer that might be beneficial under certain environmental conditions. The horizontal gene transfer contributes to the diversification and adaptation of microorganisms, thus having an impact on the genome plasticity. A significant part of the horizontal gene transfer is or has been facilitated by genomic islands (GEIs). GEIs are discrete DNA segments, some of which are mobile and others which are not, or are no longer mobile, which differ among closely related strains. A number of GEIs are capable of integration into the chromosome of the host, excision, and transfer to a new host by transformation, conjugation or transduction. GEIs play a crucial role in the evolution of a broad spectrum of bacteria as they are involved in the dissemination of variable genes, including antibiotic resistance and virulence genes leading to generation of hospital ‘superbugs’, as well as catabolic genes leading to formation of new metabolic pathways. Depending on the composition of gene modules, the same type of GEIs can promote survival of pathogenic as well as environmental bacteria.
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Affiliation(s)
- Mario Juhas
- Clinical Microbiology and Infectious Diseases, Nuffield Department of Clinical Laboratory Sciences, University of Oxford, Oxford, UK.
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Abstract
SUMMARY Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).
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Terhes G, Brazier JS, Sóki J, Urbán E, Nagy E. Coincidence of bft and cfiA genes in a multi-resistant clinical isolate of Bacteroides fragilis. J Med Microbiol 2007; 56:1416-1418. [PMID: 17893185 DOI: 10.1099/jmm.0.47242-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Gabriella Terhes
- Department of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
| | - Jon S Brazier
- Anaerobe Reference Laboratory, NPHS Microbiology Cardiff, University Hospital of Wales, Cardiff, UK
| | - József Sóki
- Department of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
| | - Edit Urbán
- Department of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
| | - Elisabeth Nagy
- Department of Clinical Microbiology, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
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Salyers AA, Moon K, Schlessinger D. The human intestinal tract – a hotbed of resistance gene transfer? Part II. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.clinmicnews.2007.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Wagner RD. Efficacy and food safety considerations of poultry competitive exclusion products. Mol Nutr Food Res 2006; 50:1061-71. [PMID: 17039457 DOI: 10.1002/mnfr.200600058] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Competitive exclusion (CE) products are anaerobic cultures of bacteria that are applied to poultry hatchlings to establish a protective enteric microbiota that excludes intestinal colonization by human food-borne pathogens. For safety of the poultry flock and human consumers, the identities of bacteria in CE products need to be known. A CE product is a culture of intestinal contents from adult chickens. It may be microbiologically defined by analysis of bacteria isolated from the culture, but many bacteria are hard to reliably isolate, identify, and characterize with conventional techniques. Sequence analysis of 16S ribosomal RNA (rRNA) genes may be more reliable than conventional techniques to identify CE bacteria. Bacteria in CE products may contain antimicrobial drug resistance and virulence mechanisms that could be transferred to the enteric bacteria of the food animal and to the human consumer. Detection methods for specific antimicrobial drug resistance and virulence genes and the integrase genes of conjugative transposons, mostly utilizing PCR technology, are being developed that can be applied to assess these risks in CE bacteria. With improvements in efficacy, bacterial identification, and detection and control of the possible risks of gene transfer, CE product technology can be made a more effective food safety tool.
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Affiliation(s)
- Robert Doug Wagner
- National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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Buckwold SL, Shoemaker NB, Sears CL, Franco AA. Identification and characterization of conjugative transposons CTn86 and CTn9343 in Bacteroides fragilis strains. Appl Environ Microbiol 2006; 73:53-63. [PMID: 17071793 PMCID: PMC1797145 DOI: 10.1128/aem.01669-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The related genetic elements flanking the Bacteroides fragilis pathogenicity island (PAI) in enterotoxigenic B. fragilis (ETBF) 86-5443-2-2 and also present in pattern III nontoxigenic B. fragilis (NTBF) NCTC 9343 were defined as putative conjugative transposons (CTns), designated CTn86 and CTn9343, respectively (A. A. Franco, J. Bacteriol. 181:6623-6633, 2004). CTn86 and CTn9343 have the same basic structures except that their encoded transposases have low similarity and CTn9343 lacks the B. fragilis PAI and contains an extra 7-kb region not present in CTn86. In this study, using DNA hybridization and PCR analysis, we characterized the genetic element flanking the PAI in a collection of ETBF strains and the related genetic elements in a collection of NTBF pattern III strains. We found that in all 123 ETBF strains, the PAI is contained in a genetic element similar to CTn86. Of 73 pattern III strains, 26 (36%) present a genetic element similar to CTn9343, 38 (52%) present a genetic element similar to CTn9343 but lack the 7-kb region that is also absent in CTn86 (CTn9343-like element), and 9 (12%) present a genetic element similar to CTn86 but lacking the PAI (CTn86-like element). In addition to containing CTn86, ETBF strains can also contain CTn9343, CTn9343-like, or CTn86-like elements. CTn86, CTn9343, CTn86-like, and CTn9343-like elements were found exclusively in B. fragilis strains and predominantly in division I, cepA-positive strains.
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Affiliation(s)
- Simy L Buckwold
- Division of Infectious Diseases, Johns Hopkins University School of Medicine, Cancer Research Building II, 1550 Orleans Street, Loading Dock, Room 1M04, Baltimore, MD 21205, USA
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Wu S, Shin J, Zhang G, Cohen M, Franco A, Sears CL. The Bacteroides fragilis toxin binds to a specific intestinal epithelial cell receptor. Infect Immun 2006; 74:5382-90. [PMID: 16926433 PMCID: PMC1594844 DOI: 10.1128/iai.00060-06] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The Bacteroides fragilis toxin (BFT) is the only known virulence factor of enterotoxigenic B. fragilis. BFT has previously been shown to act, at least in part, through cleavage of the intercellular adhesion protein E-cadherin. A specific cellular receptor for BFT has not been identified. The goal of this study was to determine if the initial interaction of BFT with intestinal epithelial cells was consistent with binding to a specific cellular receptor. Purified BFT was labeled with a fluorophore or iodide to assess specific cellular binding and the properties of BFT cellular binding. BFT binds specifically to intestinal epithelial cell lines in vitro in a polarized manner. However, specific binding occurs only at 37 degrees C and requires BFT metalloprotease activity. The BFT receptor is predicted to be a membrane protein other than E-cadherin or a known protease-activated receptor (PAR1 to PAR4). BFT binding is resistant to acid washing, suggesting an irreversible interaction. Sugar or lipid residues do not appear to be involved in the mechanism of BFT cellular binding, but binding is sensitive to membrane cholesterol depletion. We conclude that intestinal epithelial cells in vitro possess a specific membrane BFT receptor that is distinct from E-cadherin. The data favor a model in which the metalloprotease domain of BFT processes its receptor protein, initiating cellular signal transduction that mediates the biological activity of BFT. However, activation of recognized protease-activated receptors does not mimic or block BFT biological activity or binding, suggesting that additional protease-activated receptors on intestinal epithelial cells remain to be identified.
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Affiliation(s)
- Shaoguang Wu
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, 1550 Orleans St., Baltimore, MD 21231, USA
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Tobes R, Pareja E. Bacterial repetitive extragenic palindromic sequences are DNA targets for Insertion Sequence elements. BMC Genomics 2006; 7:62. [PMID: 16563168 PMCID: PMC1525189 DOI: 10.1186/1471-2164-7-62] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 03/24/2006] [Indexed: 02/04/2023] Open
Abstract
Background Mobile elements are involved in genomic rearrangements and virulence acquisition, and hence, are important elements in bacterial genome evolution. The insertion of some specific Insertion Sequences had been associated with repetitive extragenic palindromic (REP) elements. Considering that there are a sufficient number of available genomes with described REPs, and exploiting the advantage of the traceability of transposition events in genomes, we decided to exhaustively analyze the relationship between REP sequences and mobile elements. Results This global multigenome study highlights the importance of repetitive extragenic palindromic elements as target sequences for transposases. The study is based on the analysis of the DNA regions surrounding the 981 instances of Insertion Sequence elements with respect to the positioning of REP sequences in the 19 available annotated microbial genomes corresponding to species of bacteria with reported REP sequences. This analysis has allowed the detection of the specific insertion into REP sequences for ISPsy8 in Pseudomonas syringae DC3000, ISPa11 in P. aeruginosa PA01, ISPpu9 and ISPpu10 in P. putida KT2440, and ISRm22 and ISRm19 in Sinorhizobium meliloti 1021 genome. Preference for insertion in extragenic spaces with REP sequences has also been detected for ISPsy7 in P. syringae DC3000, ISRm5 in S. meliloti and ISNm1106 in Neisseria meningitidis MC58 and Z2491 genomes. Probably, the association with REP elements that we have detected analyzing genomes is only the tip of the iceberg, and this association could be even more frequent in natural isolates. Conclusion Our findings characterize REP elements as hot spots for transposition and reinforce the relationship between REP sequences and genomic plasticity mediated by mobile elements. In addition, this study defines a subset of REP-recognizer transposases with high target selectivity that can be useful in the development of new tools for genome manipulation.
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Affiliation(s)
- Raquel Tobes
- Bioinformatics Unit, Era7 Information Technologies SL, BIC Granada CEEI, Parque Tecnológico de Ciencias de la Salud – Armilla Granada 18100, Spain
| | - Eduardo Pareja
- Bioinformatics Unit, Era7 Information Technologies SL, BIC Granada CEEI, Parque Tecnológico de Ciencias de la Salud – Armilla Granada 18100, Spain
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DiChiara JM, Salyers AA, Gardner JF. In vitro analysis of sequence requirements for the excision reaction of the Bacteroides conjugative transposon, CTnDOT. Mol Microbiol 2005; 56:1035-48. [PMID: 15853888 DOI: 10.1111/j.1365-2958.2005.04585.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
CTnDOT, a Bacteroides conjugative transposon (CTn), initiates its transfer by excising to form a circular intermediate. This process has been shown to be complex, involving an unusual DNA intermediate with a short region of heterology and several CTn-encoded proteins. No information was available, however, about the sizes or sequence requirements of the att sites (attL and attR) at the ends of the integrated element where the processing occurs during excision. Using a newly developed in vitro competition excision assay, we have now localized attL to 153 bp and attR to 179 bp. Excision of CTnDOT involves staggered cuts that produce 5 bp chromosomal sequences at either end of the CTn. These 5 bp sequences (coupling sequences) form a region of heterology in the excised circular intermediate. Site-directed mutations that made the coupling sequences complementary and removed the region of heterology had no effect on excision. Thus, heterology is not essential. Mutagenesis of sequences adjacent to the coupling sequences revealed a 6 bp site in attR that was essential for excision. Mutating the analogous region in attL had little effect on excision. Regions within the attL site that appear to play a role in excision were found by introducing small insertions (phasing mutations) that could interfere with protein-protein or protein-DNA interactions. Similar insertion mutations in attR had no significant effect on excision. These results support the hypothesis that the CTnDOT excision reaction is asymmetrical with respect to likely protein binding sites and involves multiple protein-DNA interactions.
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Affiliation(s)
- Jeanne M DiChiara
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
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Franco AA, Buckwold SL, Shin JW, Ascon M, Sears CL. Mutation of the zinc-binding metalloprotease motif affects Bacteroides fragilis toxin activity but does not affect propeptide processing. Infect Immun 2005; 73:5273-7. [PMID: 16041055 PMCID: PMC1201259 DOI: 10.1128/iai.73.8.5273-5277.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
To evaluate the role of the zinc-binding metalloprotease in Bacteroides fragilis toxin (BFT) processing and activity, the zinc-binding consensus sequences (H348, E349, H352, G355, H358, and M366) were mutated by site-directed-mutagenesis. Our results indicated that single point mutations in the zinc-binding metalloprotease motif do not affect BFT processing but do reduce or eliminate BFT biologic activity in vitro.
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Affiliation(s)
- Augusto A Franco
- Division of Infectious Diseases, Johns Hopkins University School of Medicine, Ross Bldg., Rm. 1167, 1147B Rutland Ave., Baltimore, MD 21205, USA.
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Claros MC, Claros ZC, Hecht DW, Citron DM, Goldstein EJC, Silva J, Tang-Feldman Y, Rodloff AC. Characterization of the Bacteroides fragilis pathogenicity island in human blood culture isolates. Anaerobe 2005; 12:17-22. [PMID: 16701608 DOI: 10.1016/j.anaerobe.2005.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 06/15/2005] [Accepted: 06/15/2005] [Indexed: 11/20/2022]
Abstract
Bacteroides fragilis is an important anaerobic pathogen accounting for up to 10% of bacteremias in adult patients. Enterotoxin producing B. fragilis (ETBF) strains have been identified as enteric pathogens of children and adults. In order to further characterize the B. fragilis pathogenicity island (BfPAI) and using PCR assays for bft- and mpII-metalloprotease genes, we determined the frequency of B. fragilis strains with pattern I (containing the BfPAI and its flanking region), pattern II (lacking both the BfPAI and the flanking region), and pattern III (lacking the BfPAI but containing the flanking region) in 63 blood culture isolates. The results were compared to 197 B. fragilis isolates from different clinical sources. We found 19% of blood culture isolates were pattern I (ETBF), 43% were pattern II (NTBF) and 38% were pattern III (NTBF). Comparatively, B. fragilis isolates from other clinical sources were 10% pattern I, 47% pattern II and 43% pattern III. This suggests that the pathogenicity island and the flanking elements may be general virulence factors of B. fragilis.
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Affiliation(s)
- M C Claros
- Institute of Medical Microbiology and Infectious Epidemiology, University of Leipzig, Germany.
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Bacic M, Parker AC, Stagg J, Whitley HP, Wells WG, Jacob LA, Smith CJ. Genetic and structural analysis of the Bacteroides conjugative transposon CTn341. J Bacteriol 2005; 187:2858-69. [PMID: 15805532 PMCID: PMC1070377 DOI: 10.1128/jb.187.8.2858-2869.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genetic structure and functional organization of a Bacteroides conjugative transposon (CTn), CTn341, were determined. CTn341 was originally isolated from a tetracycline-resistant clinical isolate of Bacteroides vulgatus. The element was 51,993 bp long, which included a 5-bp coupling sequence that linked the transposon ends in the circular form. There were 46 genes, and the corresponding gene products fell into three major functional groups: DNA metabolism, regulation and antibiotic resistance, and conjugation. The G + C content and codon usage observed in the functional groups suggested that the groups belong to different genetic lineages, indicating that CTn341 is a composite, modular element. Mutational analysis of genes representing the different functional groups provided evidence for the gene assignments and showed that the basic conjugation and excision genes are conserved among Bacteroides spp. A group IIA1 intron, designated B.f.I1, was found to be inserted into the bmhA methylase gene. Reverse transcriptase PCR analysis of CTn341 RNA showed that B.fr.I1 was functional and was spliced out of the bmhA gene. Six related CTn-like elements were found in the genome sequences of Bacteroides fragilis NCTC9343 and Bacteroides thetaiotaomicron VPI5482. The putative elements were similar to CTn341 primarily in the tra and mob regions and in the exc gene, and several appeared to contain intron elements. Our data provide the first reported sequence for a complete Bacteroides CTn, and they should be of considerable benefit to further functional and genetic analyses of antibiotic resistance elements and genome evolution in Bacteroides.
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Affiliation(s)
- M Bacic
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, 600 Moye Blvd., Greenville, NC 27834, USA
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