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Lemay-St-Denis C, Diwan SS, Pelletier JN. The Bacterial Genomic Context of Highly Trimethoprim-Resistant DfrB Dihydrofolate Reductases Highlights an Emerging Threat to Public Health. Antibiotics (Basel) 2021; 10:433. [PMID: 33924456 PMCID: PMC8103504 DOI: 10.3390/antibiotics10040433] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 01/21/2023] Open
Abstract
Type B dihydrofolate reductase (dfrb) genes were identified following the introduction of trimethoprim in the 1960s. Although they intrinsically confer resistance to trimethoprim (TMP) that is orders of magnitude greater than through other mechanisms, the distribution and prevalence of these short (237 bp) genes is unknown. Indeed, this knowledge has been hampered by systematic biases in search methodologies. Here, we investigate the genomic context of dfrbs to gain information on their current distribution in bacterial genomes. Upon searching publicly available databases, we identified 61 sequences containing dfrbs within an analyzable genomic context. The majority (70%) of those sequences also harbor virulence genes and 97% of the dfrbs are found near a mobile genetic element, representing a potential risk for antibiotic resistance genes. We further identified and confirmed the TMP-resistant phenotype of two new members of the family, dfrb10 and dfrb11. Dfrbs are found both in Betaproteobacteria and Gammaproteobacteria, a majority (59%) being in Pseudomonas aeruginosa. Previously labelled as strictly plasmid-borne, we found 69% of dfrbs in the chromosome of pathogenic bacteria. Our results demonstrate that the intrinsically TMP-resistant dfrbs are a potential emerging threat to public health and justify closer surveillance of these genes.
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Affiliation(s)
- Claudèle Lemay-St-Denis
- Department of Biochemistry and Molecular Medecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (C.L.-S.-D.); (S.-S.D.)
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, QC G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC H3A 0B8, Canada
| | - Sarah-Slim Diwan
- Department of Biochemistry and Molecular Medecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (C.L.-S.-D.); (S.-S.D.)
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, QC G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC H3A 0B8, Canada
| | - Joelle N. Pelletier
- Department of Biochemistry and Molecular Medecine, Université de Montréal, Montréal, QC H3T 1J4, Canada; (C.L.-S.-D.); (S.-S.D.)
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, QC G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC H3A 0B8, Canada
- Chemistry Department, Université de Montréal, Montréal, QC H2V 0B3, Canada
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Reddy TR, Fevat LMS, Munson SE, Stewart AF, Cowley SM. Lambda red mediated gap repair utilizes a novel replicative intermediate in Escherichia coli. PLoS One 2015; 10:e0120681. [PMID: 25803509 PMCID: PMC4372340 DOI: 10.1371/journal.pone.0120681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/05/2015] [Indexed: 11/19/2022] Open
Abstract
The lambda phage Red recombination system can mediate efficient homologous recombination in Escherichia coli, which is the basis of the DNA engineering technique termed recombineering. Red mediated insertion of DNA requires DNA replication, involves a single-stranded DNA intermediate and is more efficient on the lagging strand of the replication fork. Lagging strand recombination has also been postulated to explain the Red mediated repair of gapped plasmids by an Okazaki fragment gap filling model. Here, we demonstrate that gap repair involves a different strand independent mechanism. Gap repair assays examining the strand asymmetry of recombination did not show a lagging strand bias. Directly testing an ssDNA plasmid showed lagging strand recombination is possible but dsDNA plasmids did not employ this mechanism. Insertional recombination combined with gap repair also did not demonstrate preferential lagging strand bias, supporting a different gap repair mechanism. The predominant recombination route involved concerted insertion and subcloning though other routes also operated at lower frequencies. Simultaneous insertion of DNA resulted in modification of both strands and was unaffected by mutations to DNA polymerase I, responsible for Okazaki fragment maturation. The lower efficiency of an alternate Red mediated ends-in recombination pathway and the apparent lack of a Holliday junction intermediate suggested that gap repair does not involve a different Red recombination pathway. Our results may be explained by a novel replicative intermediate in gap repair that does not involve a replication fork. We exploited these observations by developing a new recombineering application based on concerted insertion and gap repair, termed SPI (subcloning plus insertion). SPI selected against empty vector background and selected for correct gap repair recombinants. We used SPI to simultaneously insert up to four different gene cassettes in a single recombineering reaction. Consequently, our findings have important implications for the understanding of E. coli replication and Red recombination.
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Affiliation(s)
- Thimma R. Reddy
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Léna M. S. Fevat
- Center for Fisheries, Environment and Aquaculture Sciences, Lowestoft, United Kingdom
| | - Sarah E. Munson
- ES Cell Facility, Centre for Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - A. Francis Stewart
- Genomics, BioInnovationsZentrum, Technische Universitaet Dresden, Dresden, Germany
| | - Shaun M. Cowley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Cabreiro F, Au C, Leung KY, Vergara-Irigaray N, Cochemé H, Noori T, Weinkove D, Schuster E, Greene N, Gems D. Metformin retards aging in C. elegans by altering microbial folate and methionine metabolism. Cell 2013; 153:228-39. [PMID: 23540700 PMCID: PMC3898468 DOI: 10.1016/j.cell.2013.02.035] [Citation(s) in RCA: 689] [Impact Index Per Article: 62.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 11/07/2012] [Accepted: 02/11/2013] [Indexed: 12/19/2022]
Abstract
The biguanide drug metformin is widely prescribed to treat type 2 diabetes and metabolic syndrome, but its mode of action remains uncertain. Metformin also increases lifespan in Caenorhabditis elegans cocultured with Escherichia coli. This bacterium exerts complex nutritional and pathogenic effects on its nematode predator/host that impact health and aging. We report that metformin increases lifespan by altering microbial folate and methionine metabolism. Alterations in metformin-induced longevity by mutation of worm methionine synthase (metr-1) and S-adenosylmethionine synthase (sams-1) imply metformin-induced methionine restriction in the host, consistent with action of this drug as a dietary restriction mimetic. Metformin increases or decreases worm lifespan, depending on E. coli strain metformin sensitivity and glucose concentration. In mammals, the intestinal microbiome influences host metabolism, including development of metabolic disease. Thus, metformin-induced alteration of microbial metabolism could contribute to therapeutic efficacy—and also to its side effects, which include folate deficiency and gastrointestinal upset. PaperClip
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Affiliation(s)
- Filipe Cabreiro
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
| | - Catherine Au
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
| | - Kit-Yi Leung
- Neural Development Unit, Institute of Child Health, University College London, London WC1N 1EH, UK
| | | | - Helena M. Cochemé
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
| | - Tahereh Noori
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
| | - David Weinkove
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Eugene Schuster
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
| | - Nicholas D.E. Greene
- Neural Development Unit, Institute of Child Health, University College London, London WC1N 1EH, UK
| | - David Gems
- Institute of Healthy Ageing, and G.E.E., University College London, London WC1E 6BT, UK
- Corresponding author
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