1
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Lemay-St-Denis C, Pelletier JN. From a binding module to essential catalytic activity: how nature stumbled on a good thing. Chem Commun (Camb) 2023; 59:12560-12572. [PMID: 37791701 DOI: 10.1039/d3cc04209j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Enzymes are complex macromolecules capable of catalyzing a wide variety of chemical reactions with high efficiency. Nonetheless, biological catalysis can be rudimentary. Here, we describe an enzyme that is built from a simple protein fold. This short protein sequence - almost a peptide - belongs to the ancient SH3 family of binding modules. Surprisingly, this binding module catalyzes the specific reduction of dihydrofolate using NADPH as a reducing cofactor, making this a dihydrofolate reductase. Too small to provide all the required binding and catalytic machinery on its own, it homotetramerizes, thus creating a large, central active site environment. Remarkably, none of the active site residues is essential to the catalytic function. Instead, backbone interactions juxtapose the reducing cofactor proximal to the target imine of the folate substrate, and a specific motion of the substrate promotes formation of the transition state. In this feature article, we describe the features that make this small protein a functional enzyme capable of catalyzing a metabolically essential reaction, highlighting the characteristics that make it a model for the evolution of primitive enzymes from binding modules.
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Affiliation(s)
- Claudèle Lemay-St-Denis
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Quebec, QC, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montreal, QC, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, QC, Canada
| | - Joelle N Pelletier
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Quebec, QC, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montreal, QC, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, QC, Canada
- Chemistry Department, Université de Montréal, Montreal, QC, Canada.
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2
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Kneis D, Lemay-St-Denis C, Cellier-Goetghebeur S, Elena AX, Berendonk TU, Pelletier JN, Heß S. Trimethoprim resistance in surface and wastewater is mediated by contrasting variants of the dfrB gene. THE ISME JOURNAL 2023; 17:1455-1466. [PMID: 37369703 PMCID: PMC10432401 DOI: 10.1038/s41396-023-01460-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023]
Abstract
Trimethoprim (TMP) is a low-cost, widely prescribed antibiotic. Its effectiveness is increasingly challenged by the spread of genes coding for TMP-resistant dihydrofolate reductases: dfrA, and the lesser-known, evolutionarily unrelated dfrB. Despite recent reports of novel variants conferring high level TMP resistance (dfrB10 to dfrB21), the prevalence of dfrB is still unknown due to underreporting, heterogeneity of the analyzed genetic material in terms of isolation sources, and limited bioinformatic processing. In this study, we explored a coherent set of shotgun metagenomic sequences to quantitatively estimate the abundance of dfrB gene variants in aquatic environments. Specifically, we scanned sequences originating from influents and effluents of municipal sewage treatment plants as well as river-borne microbiomes. Our analyses reveal an increased prevalence of dfrB1, dfrB2, dfrB3, dfrB4, dfrB5, and dfrB7 in wastewater microbiomes as compared to freshwater. These gene variants were frequently found in genomic neighborship with other resistance genes, transposable elements, and integrons, indicating their mobility. By contrast, the relative abundances of the more recently discovered variants dfrB9, dfrB10, and dfrB13 were significantly higher in freshwater than in wastewater microbiomes. Moreover, their direct neighborship with other resistance genes or markers of mobile genetic elements was significantly less likely. Our findings suggest that natural freshwater communities form a major reservoir of the recently discovered dfrB gene variants. Their proliferation and mobilization in response to the exposure of freshwater communities to selective TMP concentrations may promote the prevalence of high-level TMP resistance and thus limit the future effectiveness of antimicrobial therapies.
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Affiliation(s)
- David Kneis
- TU Dresden, Institute of Hydrobiology, 01062, Dresden, Germany.
| | - Claudèle Lemay-St-Denis
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Quebec, QC, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC, Canada
- Department of Biochemistry & Molecular Medicine, University of Montréal, Montréal, QC, H3T 1J4, Canada
| | - Stella Cellier-Goetghebeur
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Quebec, QC, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC, Canada
- Department of Biochemistry & Molecular Medicine, University of Montréal, Montréal, QC, H3T 1J4, Canada
| | - Alan X Elena
- TU Dresden, Institute of Hydrobiology, 01062, Dresden, Germany
| | | | - Joelle N Pelletier
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Quebec, QC, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, QC, Canada
- Department of Biochemistry & Molecular Medicine, University of Montréal, Montréal, QC, H3T 1J4, Canada
- Chemistry Department, University of Montréal, Montréal, QC, H2V 0B3, Canada
| | - Stefanie Heß
- TU Dresden, Institute of Microbiology, 01062, Dresden, Germany
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3
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Li D, Elankumaran P, Kudinha T, Kidsley AK, Trott DJ, Jarocki VM, Djordjevic SP. Dominance of Escherichia coli sequence types ST73, ST95, ST127 and ST131 in Australian urine isolates: a genomic analysis of antimicrobial resistance and virulence linked to F plasmids. Microb Genom 2023; 9:mgen001068. [PMID: 37471138 PMCID: PMC10438821 DOI: 10.1099/mgen.0.001068] [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: 12/12/2022] [Accepted: 06/20/2023] [Indexed: 07/21/2023] Open
Abstract
Extraintestinal pathogenic Escherichia coli (ExPEC) are the most frequent cause of urinary tract infections (UTIs) globally. Most studies of clinical E. coli isolates are selected based on their antimicrobial resistance (AMR) phenotypes; however, this selection bias may not provide an accurate portrayal of which sequence types (STs) cause the most disease. Here, whole genome sequencing (WGS) was performed on 320 E. coli isolates from urine samples sourced from a regional hospital in Australia in 2006. Most isolates (91%) were sourced from patients with UTIs and were not selected based on any AMR phenotypes. No significant differences were observed in AMR and virulence genes profiles across age sex, and uro-clinical syndromes. While 88 STs were identified, ST73, ST95, ST127 and ST131 dominated. F virulence plasmids carrying senB-cjrABC (126/231; 55%) virulence genes were a feature of this collection. These senB-cjrABC+ plasmids were split into two categories: pUTI89-like (F29:A-:B10 and/or >95 % identity to pUTI89) (n=73) and non-pUTI89-like (n=53). Compared to all other plasmid replicons, isolates with pUTI89-like plasmids carried fewer antibiotic resistance genes (ARGs), whilst isolates with senB-cjrABC+/non-pUTI89 plasmids had a significantly higher load of ARGs and class 1 integrons. F plasmids were not detected in 89 genomes, predominantly ST73. Our phylogenomic analyses identified closely related isolates from the same patient associated with different pathologies and evidence of strain-sharing events involving isolates sourced from companion and wild animals.
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Affiliation(s)
- Dmitriy Li
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Paarthiphan Elankumaran
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Timothy Kudinha
- Central West Pathology Laboratory, Charles Sturt University, Orange, NSW, Australia
| | - Amanda K. Kidsley
- School of Animal and Veterinary Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Darren J. Trott
- School of Animal and Veterinary Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Veronica Maria Jarocki
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
| | - Steven Philip Djordjevic
- Australian Institute for Microbiology & Infection, University of Technology Sydney, Ultimo, NSW, Australia
- Australian Centre for Genomic Epidemiological Microbiology, University of Technology Sydney, NSW, Australia
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4
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Pham DN, Wu Q, Li M. Global profiling of antibiotic resistomes in maize rhizospheres. Arch Microbiol 2023; 205:89. [PMID: 36781495 DOI: 10.1007/s00203-023-03424-z] [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: 11/21/2022] [Revised: 01/13/2023] [Accepted: 01/24/2023] [Indexed: 02/15/2023]
Abstract
The spreading of antimicrobial resistance (AMR) in crops and food products represents a global concern. In this study, we conducted a survey of resistomes in maize rhizosphere from Michigan, California, the Netherlands, and South Africa, and investigated potential associations with host bacteria and soil management practices in the crop field. For comparison, relative abundance of antibiotic resistance genes (ARGs) is normalized to the size of individual metagenomes. Michigan maize rhizosphere metagenomes showed the highest abundance and diversity of ARGs, with the detection of blaTEM-116, blaACT-4/-6, and FosA2, exhibiting high similarity (≥ 99.0%) to those in animal and human pathogens. This was probably related to the decade-long application of manure/composted manure from antibiotic-treated animals. Moreover, RbpA, vanRO, mtrA, and dfrB were prevalently found across most studied regions, implying their intrinsic origins. Further analysis revealed that RbpA, vanRO, and mtrA are mainly harbored by native Actinobacteria with low mobility since mobile genetic elements were rarely found in their flanking regions. Notably, a group of dfrB genes are adjacent to the recombination binding sites (attC), which together constitute mobile gene cassettes, promoting the transmission from soil bacteria to human pathogens. These results suggest that maize rhizosphere resistomes can be distinctive and affected by many factors, particularly those relevant to agricultural practices.
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Affiliation(s)
- Dung Ngoc Pham
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Qiong Wu
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Mengyan Li
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, 07102, USA.
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5
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Cisneros AF, Gagnon-Arsenault I, Dubé AK, Després PC, Kumar P, Lafontaine K, Pelletier JN, Landry CR. Epistasis between promoter activity and coding mutations shapes gene evolvability. SCIENCE ADVANCES 2023; 9:eadd9109. [PMID: 36735790 PMCID: PMC9897669 DOI: 10.1126/sciadv.add9109] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 12/22/2022] [Indexed: 06/01/2023]
Abstract
The evolution of protein-coding genes proceeds as mutations act on two main dimensions: regulation of transcription level and the coding sequence. The extent and impact of the connection between these two dimensions are largely unknown because they have generally been studied independently. By measuring the fitness effects of all possible mutations on a protein complex at various levels of promoter activity, we show that promoter activity at the optimal level for the wild-type protein masks the effects of both deleterious and beneficial coding mutations. Mutations that are deleterious at low activity but masked at optimal activity are slightly destabilizing for individual subunits and binding interfaces. Coding mutations that increase protein abundance are beneficial at low expression but could potentially incur a cost at high promoter activity. We thereby demonstrate that promoter activity in interaction with protein properties can dictate which coding mutations are beneficial, neutral, or deleterious.
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Affiliation(s)
- Angel F. Cisneros
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Institut de biologie intégrative et des systèmes, Université Laval, G1V 0A6, Québec, Canada
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Centre de recherche sur les données massives, Université Laval, G1V 0A6, Québec, Canada
| | - Isabelle Gagnon-Arsenault
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Institut de biologie intégrative et des systèmes, Université Laval, G1V 0A6, Québec, Canada
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Centre de recherche sur les données massives, Université Laval, G1V 0A6, Québec, Canada
- Département de biologie, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
| | - Alexandre K. Dubé
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Institut de biologie intégrative et des systèmes, Université Laval, G1V 0A6, Québec, Canada
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Centre de recherche sur les données massives, Université Laval, G1V 0A6, Québec, Canada
- Département de biologie, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
| | - Philippe C. Després
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Institut de biologie intégrative et des systèmes, Université Laval, G1V 0A6, Québec, Canada
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Centre de recherche sur les données massives, Université Laval, G1V 0A6, Québec, Canada
| | - Pradum Kumar
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Kiana Lafontaine
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Département de biochimie et de médecine moléculaire, Faculté de médecine, Université de Montréal, H3C 3J7, Montréal, Canada
| | - Joelle N. Pelletier
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Département de biochimie et de médecine moléculaire, Faculté de médecine, Université de Montréal, H3C 3J7, Montréal, Canada
- Département de chimie, Faculté des arts et des sciences, Université de Montréal, H3C 3J7, Montréal, Canada
| | - Christian R. Landry
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
- Institut de biologie intégrative et des systèmes, Université Laval, G1V 0A6, Québec, Canada
- PROTEO, Le regroupement québécois de recherche sur la fonction, l’ingénierie et les applications des protéines, Université Laval, G1V 0A6, Québec, Canada
- Centre de recherche sur les données massives, Université Laval, G1V 0A6, Québec, Canada
- Département de biologie, Faculté des sciences et de génie, Université Laval, G1V 0A6, Québec, Canada
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6
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Cellier-Goetghebeur S, Lafontaine K, Lemay-St-Denis C, Tsamo P, Bonneau-Burke A, Copp JN, Pelletier JN. Discovery of Highly Trimethoprim-Resistant DfrB Dihydrofolate Reductases in Diverse Environmental Settings Suggests an Evolutionary Advantage Unrelated to Antibiotic Resistance. Antibiotics (Basel) 2022; 11:antibiotics11121768. [PMID: 36551425 PMCID: PMC9774602 DOI: 10.3390/antibiotics11121768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022] Open
Abstract
Type B dihydrofolate reductases (DfrB) are intrinsically highly resistant to the widely used antibiotic trimethoprim, posing a threat to global public health. The ten known DfrB family members have been strongly associated with genetic material related to the application of antibiotics. Several dfrB genes were associated with multidrug resistance contexts and mobile genetic elements, integrated both in chromosomes and plasmids. However, little is known regarding their presence in other environments. Here, we investigated the presence of dfrB beyond the traditional areas of enquiry by conducting metagenomic database searches from environmental settings where antibiotics are not prevalent. Thirty putative DfrB homologues that share 62 to 95% identity with characterized DfrB were identified. Expression of ten representative homologues verified trimethoprim resistance in all and dihydrofolate reductase activity in most. Contrary to samples associated with the use of antibiotics, the newly identified dfrB were rarely associated with mobile genetic elements or antibiotic resistance genes. Instead, association with metabolic enzymes was observed, suggesting an evolutionary advantage unrelated to antibiotic resistance. Our results are consistent with the hypothesis that multiple dfrB exist in diverse environments from which dfrB were mobilized into the clinically relevant resistome. Our observations reinforce the need to closely monitor their progression.
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Affiliation(s)
- Stella Cellier-Goetghebeur
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- 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
| | - Kiana Lafontaine
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- 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
| | - Claudèle Lemay-St-Denis
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- 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
| | - Princesse Tsamo
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- 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
| | - Alexis Bonneau-Burke
- 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
| | - Janine N. Copp
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Joelle N. Pelletier
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- 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
- Correspondence:
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7
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Kneis D, Berendonk TU, Forslund SK, Hess S. Antibiotic Resistance Genes in River Biofilms: A Metagenomic Approach toward the Identification of Sources and Candidate Hosts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14913-14922. [PMID: 35468283 PMCID: PMC9631990 DOI: 10.1021/acs.est.2c00370] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Treated wastewater is a major pathway by which antibiotic resistance genes (ARG) enter aquatic ecosystems. However, knowledge gaps remain concerning the dissemination of specific ARG and their association with bacterial hosts. Here, we employed shotgun metagenomics to track ARG and taxonomic markers in river biofilms along a gradient of fecal pollution depicted by crAssphage signatures. We found strong evidence for an impact of wastewater effluents on both community composition and resistomes. In the light of such simultaneity, we employed a model comparison technique to identify ARG-host relationships from nonassembled metagenomic DNA. Hereby, a major cause of spurious associations otherwise encountered in correlation-based ARG-host analyses was suppressed. For several families of ARG, namely those conferring resistance to beta-lactams, particular bacterial orders were identified as candidate hosts. The found associations of blaFOX and cphA with Aeromonadales or blaPER with Chromatiales support the outcome of independent evolutionary analyses and thus confirm the potential of the methodology. For other ARG families including blaIMP or tet, clusters of bacterial orders were identified which potentially harbor a major proportion of host species. For yet other ARG, like, for example, ant or erm, no particular host candidates were identifiable, indicating their spread across various taxonomic groups.
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Affiliation(s)
- David Kneis
- Technische
Universität Dresden, Institute of
Hydrobiology, 01062 Dresden, Germany
| | - Thomas U. Berendonk
- Technische
Universität Dresden, Institute of
Hydrobiology, 01062 Dresden, Germany
| | - Sofia K. Forslund
- Experimental
and Clinical Research Center, Charitéplatz 1, 10117 Berlin, Germany
- Max
Delbrück Center for Molecular Medicine, R.-Rössle-Straße 10, 13125 Berlin, Germany
- Charité
University Hospital, Charitéplatz 1, 10117 Berlin, Germany
- German
Centre for Cardiovascular Research, Potsdamer Straße 58, 10785 Berlin, Germany
- European
Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Stefanie Hess
- TU
Dresden, Institute of Microbiology, 01062 Dresden, Germany
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8
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Zhang Y, Chowdhury S, Rodrigues JV, Shakhnovich E. Development of antibacterial compounds that constrain evolutionary pathways to resistance. eLife 2021; 10:64518. [PMID: 34279221 PMCID: PMC8331180 DOI: 10.7554/elife.64518] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 07/13/2021] [Indexed: 01/27/2023] Open
Abstract
Antibiotic resistance is a worldwide challenge. A potential approach to block resistance is to simultaneously inhibit WT and known escape variants of the target bacterial protein. Here, we applied an integrated computational and experimental approach to discover compounds that inhibit both WT and trimethoprim (TMP) resistant mutants of E. coli dihydrofolate reductase (DHFR). We identified a novel compound (CD15-3) that inhibits WT DHFR and its TMP resistant variants L28R, P21L and A26T with IC50 50–75 µM against WT and TMP-resistant strains. Resistance to CD15-3 was dramatically delayed compared to TMP in in vitro evolution. Whole genome sequencing of CD15-3-resistant strains showed no mutations in the target folA locus. Rather, gene duplication of several efflux pumps gave rise to weak (about twofold increase in IC50) resistance against CD15-3. Altogether, our results demonstrate the promise of strategy to develop evolution drugs - compounds which constrain evolutionary escape routes in pathogens.
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Affiliation(s)
- Yanmin Zhang
- School of Science, China Pharmaceutical University, Nanjing, China.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Sourav Chowdhury
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - João V Rodrigues
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
| | - Eugene Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States
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9
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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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10
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Li D, Reid CJ, Kudinha T, Jarocki VM, Djordjevic SP. Genomic analysis of trimethoprim-resistant extraintestinal pathogenic Escherichia coli and recurrent urinary tract infections. Microb Genom 2020; 6:mgen000475. [PMID: 33206038 PMCID: PMC8116683 DOI: 10.1099/mgen.0.000475] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022] Open
Abstract
Urinary tract infections (UTIs) are the most common bacterial infections requiring medical attention and a leading justification for antibiotic prescription. Trimethoprim is prescribed empirically for uncomplicated cases. UTIs are primarily caused by extraintestinal pathogenic Escherichia coli (ExPEC) and ExPEC strains play a central role in disseminating antimicrobial-resistance genes worldwide. Here, we describe the whole-genome sequences of trimethoprim-resistant ExPEC and/or ExPEC from recurrent UTIs (67 in total) from patients attending a regional Australian hospital from 2006 to 2008. Twenty-three sequence types (STs) were observed, with ST131 predominating (28 %), then ST69 and ST73 (both 7 %). Co-occurrence of trimethoprim-resistance genes with genes conferring resistance to extended-spectrum β-lactams, heavy metals and quaternary ammonium ions was a feature of the ExPEC described here. Seven trimethoprim-resistance genes were identified, most commonly dfrA17 (38 %) and dfrA12 (18 %). An uncommon dfrB4 variant was also observed. Two blaCTX-M variants were identified - blaCTX-M-15 (16 %) and blaCTX-M-14 (10 %). The former was always associated with dfrA12, the latter with dfrA17, and all blaCTX-M genes co-occurred with chromate-resistance gene chrA. Eighteen class 1 integron structures were characterized, and chrA featured in eight structures; dfrA genes featured in seventeen. ST131 H30Rx isolates possessed distinct antimicrobial gene profiles comprising aac(3)-IIa, aac(6)-Ib-cr, aph(3')-Ia, aadA2, blaCTX-M-15, blaOXA-1 and dfrA12. The most common virulence-associated genes (VAGs) were fimH, fyuA, irp2 and sitA (all 91 %). Virulence profile clustering showed ST131 H30 isolates carried similar VAGs to ST73, ST405, ST550 and ST1193 isolates. The sole ST131 H27 isolate carried molecular predictors of enteroaggregative E. coli/ExPEC hybrid strains (aatA, aggR, fyuA). Seven isolates (10 %) carried VAGs suggesting ColV plasmid carriage. Finally, SNP analysis of serial UTI patients experiencing worsening sequelae demonstrated a high proportion of point mutations in virulence factors.
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Affiliation(s)
- Dmitriy Li
- Ithree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Cameron J. Reid
- Ithree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Timothy Kudinha
- NSW Health Pathology, Microbiology, Orange Hospital, Orange, NSW 2800, Australia
- School of Biomedical Sciences, Charles Sturt University, Orange, NSW 2800, Australia
| | - Veronica M. Jarocki
- Ithree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
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11
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Toulouse JL, Shi G, Lemay-St-Denis C, Ebert MCCJC, Deon D, Gagnon M, Ruediger E, Saint-Jacques K, Forge D, Vanden Eynde JJ, Marinier A, Ji X, Pelletier JN. Dual-Target Inhibitors of the Folate Pathway Inhibit Intrinsically Trimethoprim-Resistant DfrB Dihydrofolate Reductases. ACS Med Chem Lett 2020; 11:2261-2267. [PMID: 33214838 DOI: 10.1021/acsmedchemlett.0c00393] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/28/2020] [Indexed: 12/11/2022] Open
Abstract
Trimethoprim (TMP) is widely used to treat infections in humans and in livestock, accelerating the incidence of TMP resistance. The emergent and largely untracked type II dihydrofolate reductases (DfrBs) are intrinsically TMP-resistant plasmid-borne Dfrs that are structurally and evolutionarily unrelated to chromosomal Dfrs. We report kinetic characterization of the known DfrB family members. Their kinetic constants are conserved and all are poorly inhibited by TMP, consistent with TMP resistance. We investigate their inhibition with known and novel bisubstrate inhibitors of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK). Importantly, all are inhibited by the HPPK inhibitors, making these molecules dual-target inhibitors of two folate pathway enzymes that are strictly microbial.
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Affiliation(s)
- Jacynthe L. Toulouse
- Département de biochimie, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
- PROTEO, Quebec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Quebec H2V 0B3, Canada
| | - Genbin Shi
- Macromolecular Crystallography Laboratory, NCI, Frederick, Maryland 21702, United States
| | - Claudèle Lemay-St-Denis
- Département de biochimie, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
- PROTEO, Quebec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Quebec H2V 0B3, Canada
| | | | - Daniel Deon
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Marc Gagnon
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Edward Ruediger
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Kévin Saint-Jacques
- Département de chimie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Delphine Forge
- Laboratoire de chimie organique, Université de Mons, 7000 Mons, Belgium
| | | | - Anne Marinier
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, NCI, Frederick, Maryland 21702, United States
| | - Joelle N. Pelletier
- Département de biochimie, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
- PROTEO, Quebec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Quebec H2V 0B3, Canada
- Département de biochimie, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
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12
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Sánchez-Osuna M, Cortés P, Llagostera M, Barbé J, Erill I. Exploration into the origins and mobilization of di-hydrofolate reductase genes and the emergence of clinical resistance to trimethoprim. Microb Genom 2020; 6:mgen000440. [PMID: 32969787 PMCID: PMC7725336 DOI: 10.1099/mgen.0.000440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/08/2020] [Indexed: 01/23/2023] Open
Abstract
Trimethoprim is a synthetic antibacterial agent that targets folate biosynthesis by competitively binding to the di-hydrofolate reductase enzyme (DHFR). Trimethoprim is often administered synergistically with sulfonamide, another chemotherapeutic agent targeting the di-hydropteroate synthase (DHPS) enzyme in the same pathway. Clinical resistance to both drugs is widespread and mediated by enzyme variants capable of performing their biological function without binding to these drugs. These mutant enzymes were assumed to have arisen after the discovery of these synthetic drugs, but recent work has shown that genes conferring resistance to sulfonamide were present in the bacterial pangenome millions of years ago. Here, we apply phylogenetics and comparative genomics methods to study the largest family of mobile trimethoprim-resistance genes (dfrA). We show that most of the dfrA genes identified to date map to two large clades that likely arose from independent mobilization events. In contrast to sulfonamide resistance (sul) genes, we find evidence of recurrent mobilization in dfrA genes. Phylogenetic evidence allows us to identify novel dfrA genes in the emerging pathogen Acinetobacter baumannii, and we confirm their resistance phenotype in vitro. We also identify a cluster of dfrA homologues in cryptic plasmid and phage genomes, but we show that these enzymes do not confer resistance to trimethoprim. Our methods also allow us to pinpoint the chromosomal origin of previously reported dfrA genes, and we show that many of these ancient chromosomal genes also confer resistance to trimethoprim. Our work reveals that trimethoprim resistance predated the clinical use of this chemotherapeutic agent, but that novel mutations have likely also arisen and become mobilized following its widespread use within and outside the clinic. Hence, this work confirms that resistance to novel drugs may already be present in the bacterial pangenome, and stresses the importance of rapid mobilization as a fundamental element in the emergence and global spread of resistance determinants.
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Affiliation(s)
- Miquel Sánchez-Osuna
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pilar Cortés
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Montserrat Llagostera
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Jordi Barbé
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Ivan Erill
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA
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13
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Otero-Olarra JE, Curiel-Quesada E, Baltazar-Cruz J, Aguilera-Arreola MG, Pérez-Valdespino A. Low Cassette Variability in Class 2 and Class 1 Integrons of Aeromonas spp. Isolated from Environmental Samples. Microb Drug Resist 2020; 26:794-801. [PMID: 31990611 DOI: 10.1089/mdr.2019.0250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Integrons are prokaryotic genetic elements known to carry and exchange antibiotic resistance gene cassettes through a site-specific recombinase called integrase. In this work, 107 Aeromonas isolates from environmental origin, including fish, water, and sediments, were investigated for the presence of integrons. Using specific primers for Class 1, 2 and 3 integrases, only Class 1 and Class 2 integrons were detected. Detection of Class 2 integrases and their associated variable regions required two rounds of polymerase chain reaction (PCR). Sequencing of the intI2 amplicons confirmed them as integrase-derived products. Class 1 integrons were detected in 26 out of 107 isolates. PCR amplification of the variable regions associated to these integrons revealed an outstanding homogeneity, 25 of them having variable regions with an identical dfrA12-orfF-aadA2 cassette array and one integron carrying only the dfrA16 cassette. To assess clone diversity, chromosomal DNA from isolates was subjected to enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR), which discarded clonality in all instances. Class 2 integrons were surprisingly more prevalent than Class1 integrons, being detected in 60 out of 107 isolates. Forty-six of them showed a unique ERIC profile, while the remaining 14 strains displayed profiles that could be grouped in five different patterns. Cassette arrangements of all Class 2 variable regions were those described as the most prevalent (dfrA1-sat2-aadA1). A rather startling result of this work is the sensitivity to trimethoprim, streptomycin, and streptothricin of most strains, despite the presence of the cognate resistance genes. To know the integron distribution in environmental Aeromonas species, a phylogenetic reconstruction was done using rpoD/gyrB or rpoD/gyrA gene sequences. Isolates bearing these elements corresponded to Aeromonas hydrophila, Aeromonas veronii, Aeromonas salmonicida, Aeromonas dhakensis, Aeromonas sanarellii, Aeromonas taiwanensis, Aeromonas media, Aeromonas caviae, Aeromonas jandaei, and Aeromonas sp. This work revealed an unusual high incidence of Class 2 integrons and a low variability of cassette arrangements in environmental Aeromonas species.
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Affiliation(s)
- Jorge Erick Otero-Olarra
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Everardo Curiel-Quesada
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Jesús Baltazar-Cruz
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ma Guadalupe Aguilera-Arreola
- Department of Microbiology, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Abigail Pérez-Valdespino
- Department of Biochemistry, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City, Mexico
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14
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Toulouse J, Yachnin BJ, Ruediger EH, Deon D, Gagnon M, Saint-Jacques K, Ebert MCCC, Forge D, Bastien D, Colin DY, Vanden Eynde JJ, Marinier A, Berghuis AM, Pelletier JN. Structure-Based Design of Dimeric Bisbenzimidazole Inhibitors to an Emergent Trimethoprim-Resistant Type II Dihydrofolate Reductase Guides the Design of Monomeric Analogues. ACS OMEGA 2019; 4:10056-10069. [PMID: 31460098 PMCID: PMC6648814 DOI: 10.1021/acsomega.9b00640] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/22/2019] [Indexed: 05/18/2023]
Abstract
The worldwide use of the broad-spectrum antimicrobial trimethoprim (TMP) has induced the rise of TMP-resistant microorganisms. In addition to resistance-causing mutations of the microbial chromosomal dihydrofolate reductase (Dfr), the evolutionarily and structurally unrelated type II Dfrs (DfrBs) have been identified in TMP-resistant microorganisms. DfrBs are intrinsically TMP-resistant and allow bacterial proliferation when the microbial chromosomal Dfr is TMP-inhibited, making these enzymes important targets for inhibitor development. Furthermore, DfrBs occur in multiresistance plasmids, potentially accelerating their dissemination. We previously reported symmetrical bisbenzimidazoles that are the first selective inhibitors of the only well-characterized DfrB, DfrB1. Here, their diversification provides a new series of inhibitors (K i = 1.7-12.0 μM). Our results reveal two prominent features: terminal carboxylates and inhibitor length allow the establishment of essential interactions with DfrB1. Two crystal structures demonstrate the simultaneous binding of two inhibitor molecules in the symmetrical active site. Observations of those dimeric inhibitors inspired the design of monomeric analogues, binding in a single copy yet offering similar inhibition potency (K i = 1.1 and 7.4 μM). Inhibition of a second member of the DfrB family, DfrB4, suggests the generality of these inhibitors. These results provide key insights into inhibition of the highly TMP-resistant DfrBs, opening avenues to downstream development of antibiotics for combatting this emergent source of resistance.
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Affiliation(s)
- Jacynthe
L. Toulouse
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- CGCC,
The Center in Green Chemistry and Catalysis, Montréal H3A
0B8, Quebec, Canada
| | - Brahm J. Yachnin
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- Department
of Biochemistry, McGill University, Montréal H3A 0G4, Quebec, Canada
| | - Edward H. Ruediger
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
| | - Daniel Deon
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
| | - Marc Gagnon
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
| | - Kévin Saint-Jacques
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
- Département
de Chimie, Université de Sherbrooke, Sherbrooke J1K 0A5, Quebec, Canada
| | | | - Delphine Forge
- Laboratoire
de Chimie Organique, Université de
Mons, Mons 7000, Belgium
| | - Dominic Bastien
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- CGCC,
The Center in Green Chemistry and Catalysis, Montréal H3A
0B8, Quebec, Canada
| | - Damien Y. Colin
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- CGCC,
The Center in Green Chemistry and Catalysis, Montréal H3A
0B8, Quebec, Canada
| | | | - Anne Marinier
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
| | - Albert M. Berghuis
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- Department
of Biochemistry, McGill University, Montréal H3A 0G4, Quebec, Canada
| | - Joelle N. Pelletier
- Département
de Biochimie, Institute for Research in Immunology and Cancer
(IRIC), and Département de Chimie, Université
de Montréal, Montreal H3C 3J7, Quebec, Canada
- PROTEO,
the Québec Network for Research on Protein, Function, Engineering
and Applications, Quebec G1V 0A6, Canada
- CGCC,
The Center in Green Chemistry and Catalysis, Montréal H3A
0B8, Quebec, Canada
- E-mail: . Phone: 514-343-2124. Fax: 514-343-7586
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15
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Duff MR, Desai N, Craig MA, Agarwal PK, Howell EE. Crowders Steal Dihydrofolate Reductase Ligands through Quinary Interactions. Biochemistry 2019; 58:1198-1213. [PMID: 30724552 DOI: 10.1021/acs.biochem.8b01110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dihydrofolate reductase (DHFR) reduces dihydrofolate (DHF) to tetrahydrofolate using NADPH as a cofactor. Due to its role in one carbon metabolism, chromosomal DHFR is the target of the antibacterial drug, trimethoprim. Resistance to trimethoprim has resulted in a type II DHFR that is not structurally related to the chromosomal enzyme target. Because of its metabolic significance, understanding DHFR kinetics and ligand binding behavior in more cell-like conditions, where the total macromolecule concentration can be as great as 300 mg/mL, is important. The progress-curve kinetics and ligand binding properties of the drug target (chromosomal E. coli DHFR) and the drug resistant (R67 DHFR) enzymes were studied in the presence of macromolecular cosolutes. There were varied effects on NADPH oxidation and binding to the two DHFRs, with some cosolutes increasing affinity and others weakening binding. However, DHF binding and reduction in both DHFRs decreased in the presence of all cosolutes. The decreased binding of ligands is mostly attributed to weak associations with the macromolecules, as opposed to crowder effects on the DHFRs. Computer simulations found weak, transient interactions for both ligands with several proteins. The net charge of protein cosolutes correlated with effects on NADP+ binding, with near neutral and positively charged proteins having more detrimental effects on binding. For DHF binding, effects correlated more with the size of binding pockets on the protein crowders. These nonspecific interactions between DHFR ligands and proteins predict that the in vivo efficiency of DHFRs may be much lower than expected from their in vitro rates.
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Affiliation(s)
- Michael R Duff
- Department of Biochemistry & Cellular and Molecular Biology Department , University of Tennessee-Knoxville , Knoxville , Tennessee 37996 , United States
| | - Nidhi Desai
- Department of Biochemistry & Cellular and Molecular Biology Department , University of Tennessee-Knoxville , Knoxville , Tennessee 37996 , United States
| | - Michael A Craig
- Department of Biochemistry & Cellular and Molecular Biology Department , University of Tennessee-Knoxville , Knoxville , Tennessee 37996 , United States
| | - Pratul K Agarwal
- Department of Biochemistry & Cellular and Molecular Biology Department , University of Tennessee-Knoxville , Knoxville , Tennessee 37996 , United States
| | - Elizabeth E Howell
- Department of Biochemistry & Cellular and Molecular Biology Department , University of Tennessee-Knoxville , Knoxville , Tennessee 37996 , United States
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16
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Abstract
ABSTRACT
Bordetella bronchiseptica
is involved in respiratory tract infections mainly in dogs and pigs but may also cause infections in humans. Valid and representative data on antimicrobial susceptibility of
B. bronchiseptica
is rare. Approved antimicrobial susceptibility testing methods have been published, but very few clinical breakpoints are available. The MIC values are low for most agents but high for β-lactam antibiotics and macrolides. Information on the genetic basis of resistance is scarce. For a small number of isolates that are resistant or show elevated MICs, the molecular basis of resistance was identified. Three tetracycline resistance genes,
tet
(A),
tet
(C), and
tet
(31), coding for major facilitator superfamily efflux pumps, were identified. Two other major facilitator superfamily exporter genes confer resistance to chloramphenicol (
cmlB1
) or to chloramphenicol and florfenicol (
floR
). Two class B chloramphenicol acetyltransferase genes (
catB1
and
catB3
), which confer resistance to nonfluorinated phenicols by enzymatic inactivation, have been identified in
B. bronchiseptica
. Like the trimethoprim resistance genes
dfrA1
and
dfrB1
, which code for trimethoprim-insensitive dihydrofolate reductases, the genes
catB1
and
catB3
were located on gene cassettes and found in class 1 integrons also harboring the sulfonamide resistance gene
sul1
. In addition, the gene
sul2
has also been detected. Both
sul1
and
sul2
code for sulfonamide-insensitive dihydropteroate synthases. A gene cassette harboring the β-lactamase gene
bla
OXA-2
was also identified, whereas β-lactam resistance in
B. bronchiseptica
seems to be more likely due to reduced influx in combination with the species-specific β-lactamase encoded by
bla
BOR-1
. The resistance genes were mostly located on conjugative plasmids.
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17
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Bhojane P, Duff MR, Bafna K, Agarwal P, Stanley C, Howell EE. Small Angle Neutron Scattering Studies of R67 Dihydrofolate Reductase, a Tetrameric Protein with Intrinsically Disordered N-Termini. Biochemistry 2017; 56:5886-5899. [PMID: 29020453 PMCID: PMC5678894 DOI: 10.1021/acs.biochem.7b00822] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 10/02/2017] [Indexed: 11/28/2022]
Abstract
R67 dihydrofolate reductase (DHFR) is a homotetramer with a single active site pore and no sequence or structural homology with chromosomal DHFRs. The R67 enzyme provides resistance to trimethoprim, an active site-directed inhibitor of Escherichia coli DHFR. Sixteen to twenty N-terminal amino acids are intrinsically disordered in the R67 dimer crystal structure. Chymotrypsin cleavage of 16 N-terminal residues results in an active enzyme with a decreased stability. The space sampled by the disordered N-termini of R67 DHFR was investigated using small angle neutron scattering. From a combined analysis using molecular dynamics and the program SASSIE ( http://www.smallangles.net/sassie/SASSIE_HOME.html ), the apoenzyme displays a radius of gyration (Rg) of 21.46 ± 0.50 Å. Addition of glycine betaine, an osmolyte, does not result in folding of the termini as the Rg increases slightly to 22.78 ± 0.87 Å. SASSIE fits of the latter SANS data indicate that the disordered N-termini sample larger regions of space and remain disordered, suggesting they might function as entropic bristles. Pressure perturbation calorimetry also indicated that the volume of R67 DHFR increases upon addition of 10% betaine and decreased at 20% betaine because of the dehydration of the protein. Studies of the hydration of full-length R67 DHFR in the presence of the osmolytes betaine and dimethyl sulfoxide find around 1250 water molecules hydrating the protein. Similar studies with truncated R67 DHFR yield around 400 water molecules hydrating the protein in the presence of betaine. The difference of ∼900 waters indicates the N-termini are well-hydrated.
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Affiliation(s)
- Purva
P. Bhojane
- Department
of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, United States
| | - Michael R. Duff
- Department
of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, United States
| | - Khushboo Bafna
- Genome
Science and Technology Program, University
of Tennessee, Knoxville, Tennessee 37996-0840, United States
| | - Pratul Agarwal
- Computer
Science and Mathematics Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Christopher Stanley
- Biology
and Soft Matter Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Elizabeth E. Howell
- Department
of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, United States
- Genome
Science and Technology Program, University
of Tennessee, Knoxville, Tennessee 37996-0840, United States
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