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Rouleau FD, Dubé AK, Gagnon-Arsenault I, Dibyachintan S, Pageau A, Després PC, Lagüe P, Landry CR. Deep mutational scanning of Pneumocystis jirovecii dihydrofolate reductase reveals allosteric mechanism of resistance to an antifolate. PLoS Genet 2024; 20:e1011252. [PMID: 38683847 PMCID: PMC11125491 DOI: 10.1371/journal.pgen.1011252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 05/24/2024] [Accepted: 04/08/2024] [Indexed: 05/02/2024] Open
Abstract
Pneumocystis jirovecii is a fungal pathogen that causes pneumocystis pneumonia, a disease that mainly affects immunocompromised individuals. This fungus has historically been hard to study because of our inability to grow it in vitro. One of the main drug targets in P. jirovecii is its dihydrofolate reductase (PjDHFR). Here, by using functional complementation of the baker's yeast ortholog, we show that PjDHFR can be inhibited by the antifolate methotrexate in a dose-dependent manner. Using deep mutational scanning of PjDHFR, we identify mutations conferring resistance to methotrexate. Thirty-one sites spanning the protein have at least one mutation that leads to resistance, for a total of 355 high-confidence resistance mutations. Most resistance-inducing mutations are found inside the active site, and many are structurally equivalent to mutations known to lead to resistance to different antifolates in other organisms. Some sites show specific resistance mutations, where only a single substitution confers resistance, whereas others are more permissive, as several substitutions at these sites confer resistance. Surprisingly, one of the permissive sites (F199) is without direct contact to either ligand or cofactor, suggesting that it acts through an allosteric mechanism. Modeling changes in binding energy between F199 mutants and drug shows that most mutations destabilize interactions between the protein and the drug. This evidence points towards a more important role of this position in resistance than previously estimated and highlights potential unknown allosteric mechanisms of resistance to antifolate in DHFRs. Our results offer unprecedented resources for the interpretation of mutation effects in the main drug target of an uncultivable fungal pathogen.
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Affiliation(s)
- Francois D. Rouleau
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
| | - Alexandre K. Dubé
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
| | - Isabelle Gagnon-Arsenault
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
| | - Soham Dibyachintan
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
| | - Alicia Pageau
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
| | - Philippe C. Després
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
| | - Patrick Lagüe
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
| | - Christian R. Landry
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
- Regroupement Québécois de recherche sur la fonction, la structure et l’ingénierie des protéines (PROTEO), Université du Québec à Montréal, Montréal, Québec, Canada
- Centre de recherche en données massives de l’Université Laval (CRDM_UL), Québec, Québec, Canada
- Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Québec, Québec, Canada
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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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Lemay-St-Denis C, Alejaldre L, Jemouai Z, Lafontaine K, St-Aubin M, Hitache K, Valikhani D, Weerasinghe NW, Létourneau M, Thibodeaux CJ, Doucet N, Baron C, Copp JN, Pelletier JN. A conserved SH3-like fold in diverse putative proteins tetramerizes into an oxidoreductase providing an antimicrobial resistance phenotype. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220040. [PMID: 36633286 PMCID: PMC9835603 DOI: 10.1098/rstb.2022.0040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/20/2022] [Indexed: 01/13/2023] Open
Abstract
We present a potential mechanism for emergence of catalytic activity that is essential for survival, from a non-catalytic protein fold. The type B dihydrofolate reductase (DfrB) family of enzymes were first identified in pathogenic bacteria because their dihydrofolate reductase activity is sufficient to provide trimethoprim (TMP) resistance. DfrB enzymes are described as poorly evolved as a result of their unusual structural and kinetic features. No characterized protein shares sequence homology with DfrB enzymes; how they evolved to emerge in the modern resistome is unknown. In this work, we identify DfrB homologues from a database of putative and uncharacterized proteins. These proteins include an SH3-like fold homologous to the DfrB enzymes, embedded in a variety of additional structural domains. By means of functional, structural and biophysical characterization, we demonstrate that these distant homologues and their extracted SH3-like fold can display dihydrofolate reductase activity and confer TMP resistance. We provide evidence of tetrameric assembly and catalytic mechanism analogous to that of DfrB enzymes. These results contribute, to our knowledge, the first insights into a potential evolutionary path taken by this SH3-like fold to emerge in the modern resistome following introduction of TMP. This article is part of the theme issue 'Reactivity and mechanism in chemical and synthetic biology'.
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Affiliation(s)
- Claudèle Lemay-St-Denis
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Lorea Alejaldre
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Zakaria Jemouai
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Kiana Lafontaine
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Maxime St-Aubin
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Katia Hitache
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Donya Valikhani
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Chemistry Department, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Nuwani W. Weerasinghe
- Department of Chemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Québec H3A 0B8, Canada
| | - Myriam Létourneau
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Université du Québec, Laval, Québec H7V 1B7, Canada
| | - Christopher J. Thibodeaux
- Department of Chemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Québec H3A 0B8, Canada
| | - Nicolas Doucet
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Université du Québec, Laval, Québec H7V 1B7, Canada
| | - Christian Baron
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Janine N. Copp
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Joelle N. Pelletier
- PROTEO, The Québec Network for Research on Protein, Function, Engineering and Applications, Québec, Québec G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H2V 0B3, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
- Chemistry Department, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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4
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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: 8] [Impact Index Per Article: 8.0] [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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5
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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; 11:1768. [PMID: 36551425 PMCID: PMC9774602 DOI: 10.3390/antibiotics11121768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [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
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6
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Computational Development of Inhibitors of Plasmid-Borne Bacterial Dihydrofolate Reductase. Antibiotics (Basel) 2022; 11:antibiotics11060779. [PMID: 35740185 PMCID: PMC9220120 DOI: 10.3390/antibiotics11060779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 12/03/2022] Open
Abstract
Resistance to trimethoprim and other antibiotics targeting dihydrofolate reductase may arise in bacteria harboring an atypical, plasmid-encoded, homotetrameric dihydrofolate reductase, called R67 DHFR. Although developing inhibitors to this enzyme may be expected to be promising drugs to fight trimethoprim-resistant strains, there is a paucity of reports describing the development of such molecules. In this manuscript, we describe the design of promising lead compounds to target R67 DHFR. Density-functional calculations were first used to identify the modifications of the pterin core that yielded derivatives likely to bind the enzyme and not susceptible to being acted upon by it. These unreactive molecules were then docked to the active site, and the stability of the docking poses of the best candidates was analyzed through triplicate molecular dynamics simulations, and compared to the binding stability of the enzyme–substrate complex. Molecule 32 ([6-(methoxymethyl)-4-oxo-3,7-dihydro-4H-pyrano[2,3-d]pyrimidin-2-yl]methyl-guanidinium) was shown by this methodology to afford extremely stable binding towards R67 DHFR and to prevent simultaneous binding to the substrate. Additional docking and molecular dynamics simulations further showed that this candidate also binds strongly to the canonical prokaryotic dihydrofolate reductase and to human DHFR, and is therefore likely to be useful to the development of chemotherapeutic agents and of dual-acting antibiotics that target the two types of bacterial dihydrofolate reductase.
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7
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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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8
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Mhashal AR, Major DT. Temperature-Dependent Kinetic Isotope Effects in R67 Dihydrofolate Reductase from Path-Integral Simulations. J Phys Chem B 2021; 125:1369-1377. [PMID: 33522797 PMCID: PMC7883348 DOI: 10.1021/acs.jpcb.0c10318] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/05/2021] [Indexed: 11/28/2022]
Abstract
Calculation of temperature-dependent kinetic isotope effects (KIE) in enzymes presents a significant theoretical challenge. Additionally, it is not trivial to identify enzymes with available experimental accurate intrinsic KIEs in a range of temperatures. In the current work, we present a theoretical study of KIEs in the primitive R67 dihydrofolate reductase (DHFR) enzyme and compare with experimental work. The advantage of R67 DHFR is its significantly lower kinetic complexity compared to more evolved DHFR isoforms. We employ mass-perturbation-based path-integral simulations in conjunction with umbrella sampling and a hybrid quantum mechanics-molecular mechanics Hamiltonian. We obtain temperature-dependent KIEs in good agreement with experiments and ascribe the temperature-dependent KIEs primarily to zero-point energy effects. The active site in the primitive enzyme is found to be poorly preorganized, which allows excessive water access to the active site and results in loosely bound reacting ligands.
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Affiliation(s)
- Anil R. Mhashal
- Department of Chemistry and Institute
for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Dan Thomas Major
- Department of Chemistry and Institute
for Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
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9
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Fuente-Gómez GJ, Kellum CL, Miranda AC, Duff MR, Howell EE. Differentiation of the binding of two ligands to a tetrameric protein with a single symmetric active site by 19 F NMR. Protein Sci 2020; 30:477-484. [PMID: 33269489 PMCID: PMC7784773 DOI: 10.1002/pro.4007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/20/2020] [Accepted: 11/26/2020] [Indexed: 01/31/2023]
Abstract
R67 dihydrofolate reductase (R67 DHFR) is a plasmid‐encoded enzyme that confers resistance to the antibacterial drug trimethoprim. R67 DHFR is a tetramer with a single active site that is unusual as both cofactor and substrate are recognized by symmetry‐related residues. Such promiscuity has limited our previous efforts to differentiate ligand binding by NMR. To address this problem, we incorporated fluorine at positions 4, 5, 6, or 7 of the indole rings of tryptophans 38 and 45 and characterized the spectra to determine which probe was optimal for studying ligand binding. Two resonances were observed for all apo proteins. Unexpectedly, the W45 resonance appeared broad, and truncation of the disordered N‐termini resulted in the appearance of one sharp W45 resonance. These results are consistent with interaction of the N‐terminus with W45. Binding of the cofactor broadened W38 for all fluorine probes, whereas substrate, dihydrofolate, binding resulted in the appearance of three new resonances for 4‐ and 5‐fluoroindole labeled protein and severe line broadening for 6‐ and 7‐fluoroindole R67 DHFR. W45 became slightly broader upon ligand binding. With only two peaks in the 19F NMR spectra, our data were able to differentiate cofactor and substrate binding to the single, symmetric active site of R67 DHFR and yield binding affinities.
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Affiliation(s)
- Gabriel J Fuente-Gómez
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
| | - Creighton L Kellum
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
| | - Alexis C Miranda
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
| | - Michael R Duff
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
| | - Elizabeth E Howell
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
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10
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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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11
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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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12
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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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13
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Mhashal AR, Pshetitsky Y, Cheatum CM, Kohen A, Major DT. Evolutionary Effects on Bound Substrate pKa in Dihydrofolate Reductase. J Am Chem Soc 2018; 140:16650-16660. [DOI: 10.1021/jacs.8b09089] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Anil R. Mhashal
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yaron Pshetitsky
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | | | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Dan Thomas Major
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002, Israel
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14
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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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15
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Shionyu-Mitsuyama C, Hijikata A, Tsuji T, Shirai T. Classification of ligand molecules in PDB with graph match-based structural superposition. ACTA ACUST UNITED AC 2016; 17:135-146. [PMID: 28012138 DOI: 10.1007/s10969-016-9209-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
The fast heuristic graph match algorithm for small molecules, COMPLIG, was improved by adding a structural superposition process to verify the atom-atom matching. The modified method was used to classify the small molecule ligands in the Protein Data Bank (PDB) by their three-dimensional structures, and 16,660 types of ligands in the PDB were classified into 7561 clusters. In contrast, a classification by a previous method (without structure superposition) generated 3371 clusters from the same ligand set. The characteristic feature in the current classification system is the increased number of singleton clusters, which contained only one ligand molecule in a cluster. Inspections of the singletons in the current classification system but not in the previous one implied that the major factors for the isolation were differences in chirality, cyclic conformations, separation of substructures, and bond length. Comparisons between current and previous classification systems revealed that the superposition-based classification was effective in clustering functionally related ligands, such as drugs targeted to specific biological processes, owing to the strictness of the atom-atom matching.
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Affiliation(s)
- Clara Shionyu-Mitsuyama
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Atsushi Hijikata
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Toshiyuki Tsuji
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan
| | - Tsuyoshi Shirai
- Department of Bioscience, Nagahama Institute of Bio-science and Technology, 1266 Tamura, Nagahama, 526-0829, Japan.
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16
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Bhojane P, Duff MR, Bafna K, Rimmer GP, Agarwal PK, Howell EE. Aspects of Weak Interactions between Folate and Glycine Betaine. Biochemistry 2016; 55:6282-6294. [PMID: 27768285 PMCID: PMC5198541 DOI: 10.1021/acs.biochem.6b00873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/19/2016] [Indexed: 01/22/2023]
Abstract
Folate, or vitamin B9, is an important compound in one-carbon metabolism. Previous studies have found weaker binding of dihydrofolate to dihydrofolate reductase in the presence of osmolytes. In other words, osmolytes are more difficult to remove from the dihydrofolate solvation shell than water; this shifts the equilibrium toward the free ligand and protein species. This study uses vapor-pressure osmometry to explore the interaction of folate with the model osmolyte, glycine betaine. This method yields a preferential interaction potential (μ23/RT value). This value is concentration-dependent as folate dimerizes. The μ23/RT value also tracks the deprotonation of folate's N3-O4 keto-enol group, yielding a pKa of 8.1. To determine which folate atoms interact most strongly with betaine, the interaction of heterocyclic aromatic compounds (as well as other small molecules) with betaine was monitored. Using an accessible surface area approach coupled with osmometry measurements, deconvolution of the μ23/RT values into α values for atom types was achieved. This allows prediction of μ23/RT values for larger molecules such as folate. Molecular dynamics simulations of folate show a variety of structures from extended to L-shaped. These conformers possess μ23/RT values from -0.18 to 0.09 m-1, where a negative value indicates a preference for solvation by betaine and a positive value indicates a preference for water. This range of values is consistent with values observed in osmometry and solubility experiments. As the average predicted folate μ23/RT value is near zero, this indicates folate interacts almost equally well with betaine and water. Specifically, the glutamate tail prefers to interact with water, while the aromatic rings prefer betaine. In general, the more protonated species in our small molecule survey interact better with betaine as they provide a source of hydrogens (betaine is not a hydrogen bond donor). Upon deprotonation of the small molecule, the preference swings toward water interaction because of its hydrogen bond donating capacities.
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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
| | - Gabriella P. Rimmer
- Department
of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, United States
| | - Pratul K. Agarwal
- 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
- Computer
Science and Mathematics 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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17
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McClelland EE, Ramagopal UA, Rivera J, Cox J, Nakouzi A, Prabu MM, Almo SC, Casadevall A. A Small Protein Associated with Fungal Energy Metabolism Affects the Virulence of Cryptococcus neoformans in Mammals. PLoS Pathog 2016; 12:e1005849. [PMID: 27583447 PMCID: PMC5008624 DOI: 10.1371/journal.ppat.1005849] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/06/2016] [Indexed: 12/04/2022] Open
Abstract
The pathogenic yeast Cryptococcus neoformans causes cryptococcosis, a life-threatening fungal disease. C. neoformans has multiple virulence mechanisms that are non-host specific, induce damage and interfere with immune clearance. Microarray analysis of C. neoformans strains serially passaged in mice associated a small gene (CNAG_02591) with virulence. This gene, hereafter identified as HVA1 (hypervirulence-associated protein 1), encodes a protein that has homologs of unknown function in plant and animal fungi, consistent with a conserved mechanism. Expression of HVA1 was negatively correlated with virulence and was reduced in vitro and in vivo in both mouse- and Galleria-passaged strains of C. neoformans. Phenotypic analysis in hva1Δ and hva1Δ+HVA1 strains revealed no significant differences in established virulence factors. Mice infected intravenously with the hva1Δ strain had higher fungal burden in the spleen and brain, but lower fungal burden in the lungs, and died faster than mice infected with H99W or the hva1Δ+HVA1 strain. Metabolomics analysis demonstrated a general increase in all amino acids measured in the disrupted strain and a block in the TCA cycle at isocitrate dehydrogenase, possibly due to alterations in the nicotinamide cofactor pool. Macrophage fungal burden experiments recapitulated the mouse hypervirulent phenotype of the hva1Δ strain only in the presence of exogenous NADPH. The crystal structure of the Hva1 protein was solved, and a comparison of structurally similar proteins correlated with the metabolomics data and potential interactions with NADPH. We report a new gene that modulates virulence through a mechanism associated with changes in fungal metabolism. C. neoformans is a pathogenic yeast that is the causative agent of cryptococcal meningitis. This fungal pathogen causes disease in immune compromised hosts, primarily AIDS patients in developing countries, though it also afflicts organ transplant patients and patients undergoing chemotherapy. There are >600,000 deaths per year and >1 million new infections. Unfortunately, treatment options for C. neoformans are limited and cause high kidney and liver toxicity. Thus, understanding specific steps in pathogenesis may help with design of new therapeutics. We have identified a gene (HVA1) whose absence is associated with a hypervirulent phenotype in mice. Metabolomics analysis suggests that when HVA1 is absent there is a block in the citric acid cycle, while structural analysis of the Hva1 protein suggests a potential interaction with NADPH. Fungal burden experiments in macrophages recapitulate the hypervirulent phenotype in mice only in the presence of exogenous NADPH, suggesting that modulation of NADPH affects virulence. This work adds to the growing list of genes involved in pathogen metabolism that also contribute to virulence and pathogenesis, underscoring the need to better understand the mechanisms of how pathogen metabolism affects virulence.
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Affiliation(s)
- Erin E. McClelland
- Department of Biology, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
- * E-mail:
| | - Udupi A. Ramagopal
- Department of Biochemistry and Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Johanna Rivera
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - James Cox
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
| | - Antonio Nakouzi
- Department of Biochemistry and Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Moses M. Prabu
- M&P Associates Inc., Murfreesboro, Tennesee, United States of America
| | - Steven C. Almo
- Department of Biochemistry and Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, John Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
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18
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Duff MR, Chopra S, Strader MB, Agarwal PK, Howell EE. Tales of Dihydrofolate Binding to R67 Dihydrofolate Reductase. Biochemistry 2015; 55:133-45. [PMID: 26637016 PMCID: PMC5147970 DOI: 10.1021/acs.biochem.5b00981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Homotetrameric R67 dihydrofolate reductase possesses 222 symmetry and a single active site pore. This situation results in a promiscuous binding site that accommodates either the substrate, dihydrofolate (DHF), or the cofactor, NADPH. NADPH interacts more directly with the protein as it is larger than the substrate. In contrast, the p-aminobenzoyl-glutamate tail of DHF, as monitored by nuclear magnetic resonance and crystallography, is disordered when bound. To explore whether smaller active site volumes (which should decrease the level of tail disorder by confinement effects) alter steady state rates, asymmetric mutations that decreased the half-pore volume by ∼35% were constructed. Only minor effects on k(cat) were observed. To continue exploring the role of tail disorder in catalysis, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide-mediated cross-linking between R67 DHFR and folate was performed. A two-folate, one-tetramer complex results in the loss of enzyme activity where two symmetry-related K32 residues in the protein are cross-linked to the carboxylates of two bound folates. The tethered folate could be reduced, although with a ≤30-fold decreased rate, suggesting decreased dynamics and/or suboptimal positioning of the cross-linked folate for catalysis. Computer simulations that restrain the dihydrofolate tail near K32 indicate that cross-linking still allows movement of the p-aminobenzoyl ring, which allows the reaction to occur. Finally, a bis-ethylene-diamine-α,γ-amide folate adduct was synthesized; both negatively charged carboxylates in the glutamate tail were replaced with positively charged amines. The K(i) for this adduct was ∼9-fold higher than for folate. These various results indicate a balance between folate tail disorder, which helps the enzyme bind substrate while dynamics facilitates catalysis.
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Affiliation(s)
- Michael R Duff
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
| | - Shaileja Chopra
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
| | - Michael Brad Strader
- Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration , Silver Spring, Maryland 20993, United States
| | - Pratul K Agarwal
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States.,Computer Science and Mathematics Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Elizabeth E Howell
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
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19
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Manipulating the substrate specificity of murine dihydrofolate reductase enzyme using an expanded set of amino acids. Biochem Eng J 2015. [DOI: 10.1016/j.bej.2015.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Ebert MCCJC, Morley KL, Volpato JP, Schmitzer AR, Pelletier JN. Asymmetric mutations in the tetrameric R67 dihydrofolate reductase reveal high tolerance to active-site substitutions. Protein Sci 2014; 24:495-507. [PMID: 25401264 DOI: 10.1002/pro.2602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 11/08/2022]
Abstract
Type II R67 dihydrofolate reductase (DHFR) is a bacterial plasmid-encoded enzyme that is intrinsically resistant to the widely-administered antibiotic trimethoprim. R67 DHFR is genetically and structurally unrelated to E. coli chromosomal DHFR and has an unusual architecture, in that four identical protomers form a single symmetrical active site tunnel that allows only one substrate binding/catalytic event at any given time. As a result, substitution of an active-site residue has as many as four distinct consequences on catalysis, constituting an atypical model of enzyme evolution. Although we previously demonstrated that no single residue of the native active site is indispensable for function, library selection here revealed a strong bias toward maintenance of two native protomers per mutated tetramer. A variety of such "half-native" tetramers were shown to procure native-like catalytic activity, with similar KM values but kcat values 5- to 33-fold lower, illustrating a high tolerance for active-site substitutions. The selected variants showed a reduced thermal stability (Tm ∼12°C lower), which appears to result from looser association of the protomers, but generally showed a marked increase in resilience to heat denaturation, recovering activity to a significantly greater extent than the variant with no active-site substitutions. Our results suggest that the presence of two native protomers in the R67 DHFR tetramer is sufficient to provide native-like catalytic rate and thus ensure cellular proliferation.
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Affiliation(s)
- Maximilian C C J C Ebert
- Département de Biochimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec, H3C 3J7, Canada; PROTEO, the Québec Network for Protein Function, Structure and Engineering, Québec, Canada; CGCC, the Center for Green Chemistry and Catalysis, Montréal, Canada
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21
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Thermodynamics and solvent linkage of macromolecule-ligand interactions. Methods 2014; 76:51-60. [PMID: 25462561 DOI: 10.1016/j.ymeth.2014.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/11/2014] [Accepted: 11/13/2014] [Indexed: 02/06/2023] Open
Abstract
Binding involves two steps, desolvation and association. While water is ubiquitous and occurs at high concentration, it is typically ignored. In vitro experiments typically use infinite dilution conditions, while in vivo, the concentration of water is decreased due to the presence of high concentrations of molecules in the cellular milieu. This review discusses isothermal titration calorimetry approaches that address the role of water in binding. For example, use of D2O allows the contribution of solvent reorganization to the enthalpy component to be assessed. Further, the addition of osmolytes will decrease the water activity of a solution and allow effects on Ka to be determined. In most cases, binding becomes tighter in the presence of osmolytes as the desolvation penalty associated with binding is minimized. In other cases, the osmolytes prefer to interact with the ligand or protein, and if their removal is more difficult than shedding water, then binding can be weakened. These complicating layers can be discerned by different slopes in ln(Ka) vs osmolality plots and by differential scanning calorimetry in the presence of the osmolyte.
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22
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Bhojane PP, Duff MR, Patel HC, Vogt ME, Howell EE. Investigation of osmolyte effects on FolM: comparison with other dihydrofolate reductases. Biochemistry 2014; 53:1330-41. [PMID: 24517487 DOI: 10.1021/bi4014165] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A weak association between osmolytes and dihydrofolate (DHF) decreases the affinity of the substrate for the Escherichia coli chromosomal and R67 plasmid dihydrofolate reductase (DHFR) enzymes. To test whether the osmolyte-DHF association also interferes with binding of DHF to FolM, an E. coli enzyme that possesses weak DHFR activity, ligand binding was monitored in the presence of osmolytes. The affinity of FolM for DHF, measured by kcat/Km(DHF), was decreased by the addition of an osmolyte. Additionally, binding of the antifolate drug, methotrexate, to FolM was weakened by the addition of an osmolyte. The changes in ligand binding with water activity were unique for each osmolyte, indicating preferential interaction between the osmolyte and folate and its derivatives; however, additional evidence provided support for further interactions between FolM and osmolytes. Binding of the reduced nicotinamide adenine dinucleotide phosphate (NADPH) cofactor to FolM was monitored by isothermal titration calorimetry as a control for protein-osmolyte association. In the presence of betaine (proposed to be the osmolyte most excluded from protein surfaces), the NADPH Kd decreased, consistent with dehydration effects. However, other osmolytes did not tighten binding to the cofactor. Rather, dimethyl sulfoxide (DMSO) had no effect on the NADPH Kd, while ethylene glycol and polyethylene glycol 400 weakened cofactor binding. Differential scanning calorimetry of FolM in the presence of osmolytes showed that both DMSO and ethylene glycol decreased the stability of FolM, while betaine increased the stability of the protein. These results suggest that some osmolytes can destabilize FolM by preferentially interacting with the protein. Further, these weak attractions can impede ligand binding. These various contributions have to be considered when interpreting osmotic pressure results.
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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
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23
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Padmanabhan B, Nakamura Y, Antonyuk SV, Strange RW, Hasnain SS, Yokoyama S, Bessho Y. Structure of the hypothetical DUF1811-family protein GK0453 from Geobacillus kaustophilus HTA426. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:342-5. [PMID: 23545635 PMCID: PMC3614154 DOI: 10.1107/s1744309113003369] [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: 12/28/2012] [Accepted: 02/02/2013] [Indexed: 11/10/2022]
Abstract
The crystal structure of a conserved hypothetical protein, GK0453, from Geobacillus kaustophilus has been determined to 2.2 Å resolution. The crystal belonged to space group P4(3)2(1)2, with unit-cell parameters a = b = 75.69, c = 64.18 Å. The structure was determined by the molecular-replacement method and was refined to a final R factor of 22.6% (R(free) = 26.3%). Based on structural homology, the GK0453 protein possesses two independent binding sites and hence it may simultaneously interact with two proteins or with a protein and a nucleic acid.
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Affiliation(s)
- Balasundaram Padmanabhan
- Department of Biophysics, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore 560 029, India
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Yoshihiro Nakamura
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England
| | - Richard W. Strange
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England
| | - S. Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England
| | - Shigeyuki Yokoyama
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Laboratory of Structural Biology and Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yoshitaka Bessho
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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24
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Timson MJ, Duff MR, Dickey G, Saxton AM, Reyes-De-Corcuera JI, Howell EE. Further studies on the role of water in R67 dihydrofolate reductase. Biochemistry 2013; 52:2118-27. [PMID: 23458706 DOI: 10.1021/bi301544k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous osmotic pressure studies of two nonhomologous dihydrofolate reductase (DHFR) enzymes found tighter binding of the nicotinamide adenine dinucleotide phosphate cofactor upon addition of neutral osmolytes. This result is consistent with water release accompanying binding. In contrast, osmotic stress studies found weaker binding of the dihydrofolate (DHF) substrate for both type I and type II DHFRs in the presence of osmolytes; this observation can be explained if dihydrofolate interacts with osmolytes and shifts the equilibrium from the enzyme-bound state toward the unbound substrate. Nuclear magnetic resonance experiments support this hypothesis, finding that osmolytes interact with dihydrofolate. To consider binding without added osmolytes, a high-pressure approach was used. In this study, the type II enzyme, R67 DHFR, was subjected to high hydrostatic pressure (HHP). Both enzyme activity and fluorescence measurements find the protein tolerates pressures up to 200 MPa. Binding of the cofactor to R67 DHFR weakens with increasing pressure, and a positive association volume of 11.4 ± 0.5 cm(3)/mol was measured. Additionally, an activation volume of 3.3 ± 0.5 cm(3)/mol describing k(cat)/K(m(DHF)) was determined from progress curve analysis. Results from these HHP experiments suggest water release accompanies binding of both the cofactor and DHF to R67 DHFR. In an additional set of experiments, isothermal titration calorimetry studies in H2O and D2O find that water reorganization dominates the enthalpy associated with binding of DHF to R67 DHFR·NADP(+), while no obvious effects occur for cofactor binding. The combined results indicate that water plays an active role in ligand binding to R67 DHFR.
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Affiliation(s)
- Mary Jane Timson
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996-0840, United States
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25
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Bastien D, Ebert MCCJC, Forge D, Toulouse J, Kadnikova N, Perron F, Mayence A, Huang TL, Vanden Eynde JJ, Pelletier JN. Fragment-Based Design of Symmetrical Bis-benzimidazoles as Selective Inhibitors of the Trimethoprim-Resistant, Type II R67 Dihydrofolate Reductase. J Med Chem 2012; 55:3182-92. [DOI: 10.1021/jm201645r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dominic Bastien
- Département de Biochimie, Université de Montréal, C.P. 6128, Succ.
Centre-ville Montréal, Québec H3C 3J7, Canada
| | - Maximilian C. C. J. C. Ebert
- Département de Biochimie, Université de Montréal, C.P. 6128, Succ.
Centre-ville Montréal, Québec H3C 3J7, Canada
| | - Delphine Forge
- Laboratoire de Chimie Organique, Université de Mons-UMONS, 20 Place du Parc,
B-7000 Mons, Belgium
| | - Jacynthe Toulouse
- Département de Biochimie, Université de Montréal, C.P. 6128, Succ.
Centre-ville Montréal, Québec H3C 3J7, Canada
| | - Natalia Kadnikova
- Département
de Chimie, Université de Montréal, C.P. 6128, Succursale
Centre-ville Montréal, Québec H3C 3J7, Canada
| | - Florent Perron
- Laboratoire de Chimie Organique, Université de Mons-UMONS, 20 Place du Parc,
B-7000 Mons, Belgium
| | - Annie Mayence
- Division of Basic Pharmaceutical
Sciences, Xavier University of Louisiana, 1 Drexel Drive, New Orleans, Louisiana 70125, United States
| | - Tien L. Huang
- Division of Basic Pharmaceutical
Sciences, Xavier University of Louisiana, 1 Drexel Drive, New Orleans, Louisiana 70125, United States
| | | | - Joelle N. Pelletier
- Département de Biochimie, Université de Montréal, C.P. 6128, Succ.
Centre-ville Montréal, Québec H3C 3J7, Canada
- Département
de Chimie, Université de Montréal, C.P. 6128, Succursale
Centre-ville Montréal, Québec H3C 3J7, Canada
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26
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Evolutionarily conserved linkage between enzyme fold, flexibility, and catalysis. PLoS Biol 2011; 9:e1001193. [PMID: 22087074 PMCID: PMC3210774 DOI: 10.1371/journal.pbio.1001193] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022] Open
Abstract
Proteins are intrinsically flexible molecules. The role of internal motions in a protein's designated function is widely debated. The role of protein structure in enzyme catalysis is well established, and conservation of structural features provides vital clues to their role in function. Recently, it has been proposed that the protein function may involve multiple conformations: the observed deviations are not random thermodynamic fluctuations; rather, flexibility may be closely linked to protein function, including enzyme catalysis. We hypothesize that the argument of conservation of important structural features can also be extended to identification of protein flexibility in interconnection with enzyme function. Three classes of enzymes (prolyl-peptidyl isomerase, oxidoreductase, and nuclease) that catalyze diverse chemical reactions have been examined using detailed computational modeling. For each class, the identification and characterization of the internal protein motions coupled to the chemical step in enzyme mechanisms in multiple species show identical enzyme conformational fluctuations. In addition to the active-site residues, motions of protein surface loop regions (>10 Å away) are observed to be identical across species, and networks of conserved interactions/residues connect these highly flexible surface regions to the active-site residues that make direct contact with substrates. More interestingly, examination of reaction-coupled motions in non-homologous enzyme systems (with no structural or sequence similarity) that catalyze the same biochemical reaction shows motions that induce remarkably similar changes in the enzyme–substrate interactions during catalysis. The results indicate that the reaction-coupled flexibility is a conserved aspect of the enzyme molecular architecture. Protein motions in distal areas of homologous and non-homologous enzyme systems mediate similar changes in the active-site enzyme–substrate interactions, thereby impacting the mechanism of catalyzed chemistry. These results have implications for understanding the mechanism of allostery, and for protein engineering and drug design.
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27
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Yachnin BJ, Colin DY, Volpato JP, Ebert M, Pelletier JN, Berghuis AM. Novel crystallization conditions for tandem variant R67 DHFR yield a wild-type crystal structure. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1316-22. [PMID: 22102224 PMCID: PMC3212443 DOI: 10.1107/s1744309111030417] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 07/28/2011] [Indexed: 11/10/2022]
Abstract
Trimethoprim is an antibiotic that targets bacterial dihydrofolate reductase (DHFR). A plasmid-encoded DHFR known as R67 DHFR provides resistance to trimethoprim in bacteria. To better understand the mechanism of this homotetrameric enzyme, a tandem dimer construct was created that linked two monomeric R67 DHFR subunits together and mutated the sequence of residues 66-69 of the first subunit from VQIY to INSF. Using a modified crystallization protocol for this enzyme that included in situ proteolysis using chymotrypsin, the tandem dimer was crystallized and the structure was solved at 1.4 Å resolution. Surprisingly, only wild-type protomers were incorporated into the crystal. Further experiments demonstrated that the variant protomer was selectively degraded by chymotrypsin, although no canonical chymotrypsin cleavage site had been introduced by these mutations.
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Affiliation(s)
- Brahm J. Yachnin
- Department of Biochemistry, McGill University, 3649 Promenade Sir William Osler, Bellini Pavilion, Room 470, Montreal, Quebec H3G 0B1, Canada
- Groupe de Recherche GRASP, Canada
- Groupe de Recherche PROTEO, Canada
| | - Damien Y. Colin
- Groupe de Recherche PROTEO, Canada
- Département de Chimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
| | - Jordan P. Volpato
- Groupe de Recherche PROTEO, Canada
- Département de Biochimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
| | - Maximilian Ebert
- Groupe de Recherche PROTEO, Canada
- Département de Biochimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
| | - Joelle N. Pelletier
- Groupe de Recherche PROTEO, Canada
- Département de Chimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
- Département de Biochimie, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montreal, Quebec H3T 1J4, Canada
| | - Albert M. Berghuis
- Department of Biochemistry, McGill University, 3649 Promenade Sir William Osler, Bellini Pavilion, Room 470, Montreal, Quebec H3G 0B1, Canada
- Groupe de Recherche GRASP, Canada
- Groupe de Recherche PROTEO, Canada
- Department of Microbiology and Immunology, McGill University, 3649 Promenade Sir William Osler, Bellini Pavilion, Room 470, Montreal, Quebec H3G 0B1, Canada
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28
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Grubbs J, Rahmanian S, DeLuca A, Padmashali C, Jackson M, Duff MR, Howell EE. Thermodynamics and solvent effects on substrate and cofactor binding in Escherichia coli chromosomal dihydrofolate reductase. Biochemistry 2011; 50:3673-85. [PMID: 21462996 DOI: 10.1021/bi2002373] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Chromosomal dihydrofolate reductase from Escherichia coli catalyzes the reduction of dihydrofolate to tetrahydrofolate using NADPH as a cofactor. The thermodynamics of ligand binding were examined using an isothermal titration calorimetry approach. Using buffers with different heats of ionization, zero to a small, fractional proton release was observed for dihydrofolate binding, while a proton was released upon NADP(+) binding. The role of water in binding was additionally monitored using a number of different osmolytes. Binding of NADP(+) is accompanied by the net release of ∼5-24 water molecules, with a dependence on the identity of the osmolyte. In contrast, binding of dihydrofolate is weakened in the presence of osmolytes, consistent with "water uptake". Different effects are observed depending on the identity of the osmolyte. The net uptake of water upon dihydrofolate binding was previously observed in the nonhomologous R67-encoded dihydrofolate reductase (dfrB or type II enzyme) [Chopra, S., et al. (2008) J. Biol. Chem. 283, 4690-4698]. As R67 dihydrofolate reductase possesses a nonhomologous sequence and forms a tetrameric structure with a single active site pore, the observation of weaker DHF binding in the presence of osmolytes in both enzymes implicates cosolvent effects on free dihydrofolate. Consistent with this analysis, stopped flow experiments find betaine mostly affects DHF binding via changes in k(on), while betaine mostly affects NADPH binding via changes in k(off). Finally, nonadditive enthalpy terms when binary and ternary cofactor binding events are compared suggest the presence of long-lived conformational transitions that are not included in a simple thermodynamic cycle.
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Affiliation(s)
- Jordan Grubbs
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, USA
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29
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Kamath G, Howell EE, Agarwal PK. The Tail Wagging the Dog: Insights into Catalysis in R67 Dihydrofolate Reductase. Biochemistry 2010; 49:9078-88. [DOI: 10.1021/bi1007222] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ganesh Kamath
- Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Elizabeth E. Howell
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
| | - Pratul K. Agarwal
- Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
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Feng J, Grubbs J, Dave A, Goswami S, Horner CG, Howell EE. Radical redesign of a tandem array of four R67 dihydrofolate reductase genes yields a functional, folded protein possessing 45 substitutions. Biochemistry 2010; 49:7384-92. [PMID: 20684560 DOI: 10.1021/bi1005943] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
R67 dihydrofolate reductase (DHFR) is a plasmid-encoded, type II enzyme. Four monomers (78 amino acids long) assemble into a homotetramer possessing 222 symmetry. In previous studies, a tandem array of four R67 DHFR gene copies was fused in frame to generate a functional monomer named Quad1. This protein possessed the essential tertiary structure of the R67 "parent". To facilitate mutagenesis reactions, restriction enzyme sites were introduced in the tandem gene array. S59A and H362L mutations were also added to minimize possible folding topologies; this protein product, named Quad3, possesses 10 substitutions and is functional. Since R67 DHFR possesses a stable scaffold, a large jump in sequence space was performed by the further addition of 45 amino acid substitutions. The mutational design utilized alternate sequences from other type II DHFRs. In addition, most of the mutations were positioned on the surface of the protein as well as in the disordered N-terminal sequence, which serves as the linker between the fused domains. The resulting Quad4 protein is quite functional; however, it is less stable than Quad1, suffering a DeltaDeltaG loss of 5 kcal/mol at pH 5. One unexpected result was formation of Quad4 dimers and higher order oligomers at pH 8. R67 DHFR, and its derivative Quad proteins, possesses a robust scaffold, capable of withstanding introduction of >or=55 substitutions.
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Affiliation(s)
- Jian Feng
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, USA
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31
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Yahashiri A, Nimrod G, Ben-Tal N, Howell EE, Kohen A. The effect of electrostatic shielding on H tunneling in R67 dihydrofolate reductase. Chembiochem 2010; 10:2620-3. [PMID: 19774544 DOI: 10.1002/cbic.200900451] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Atsushi Yahashiri
- Department of Chemistry, The University of Iowa, Iowa City, IA 52242, USA
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Davis JH, Baker TA, Sauer RT. Engineering synthetic adaptors and substrates for controlled ClpXP degradation. J Biol Chem 2009; 284:21848-21855. [PMID: 19549779 DOI: 10.1074/jbc.m109.017624] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Facile control of targeted intracellular protein degradation has many potential uses in basic science and biotechnology. One promising approach to this goal is to redesign adaptor proteins, which can regulate proteolytic specificity by tethering substrates to energy-dependent AAA+ proteases. Using the ClpXP protease, we have probed the minimal biochemical functions required for adaptor function by designing and characterizing variant substrates, adaptors, and ClpX enzymes. We find that substrate tethering mediated by heterologous interaction domains and a small bridging molecule mimics substrate delivery by the wild-type system. These results show that simple tethering is sufficient for synthetic adaptor function. In our engineered system, tethering and proteolysis depend on the presence of the macrolide rapamycin, providing a foundation for engineering highly specific degradation of target proteins in cells. Importantly, this degradation is regulated by a small molecule without the need for new adaptor or enzyme biosynthesis.
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Affiliation(s)
| | - Tania A Baker
- Department of Biology, Cambridge, Massachusetts 02139; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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Yahashiri A, Howell EE, Kohen A. Tuning of the H-transfer coordinate in primitive versus well-evolved enzymes. Chemphyschem 2008; 9:980-2. [PMID: 18444258 DOI: 10.1002/cphc.200800067] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Atsushi Yahashiri
- Department of Chemistry, University of Iowa, Iowa City, IA, 52242-1294, USA
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Chopra S, Dooling RM, Horner CG, Howell EE. A balancing act between net uptake of water during dihydrofolate binding and net release of water upon NADPH binding in R67 dihydrofolate reductase. J Biol Chem 2007; 283:4690-8. [PMID: 18086667 DOI: 10.1074/jbc.m709443200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
R67 dihydrofolate reductase (DHFR) catalyzes the reduction of dihydrofolate (DHF) to tetrahydrofolate using NADPH as a cofactor. This enzyme is a homotetramer possessing 222 symmetry, and a single active site pore traverses the length of the protein. A promiscuous binding surface can accommodate either DHF or NADPH, thus two nonproductive complexes can form (2NADPH or 2DHF) as well as a productive complex (NADPH.DHF). The role of water in binding was monitored using a number of different osmolytes. From isothermal titration calorimetry (ITC) studies, binding of NADPH is accompanied by the net release of 38 water molecules. In contrast, from both steady state kinetics and ITC studies, binding of DHF is accompanied by the net uptake of water. Although different osmolytes have similar effects on NADPH binding, variable results are observed when DHF binding is probed. Sensitivity to water activity can also be probed by an in vivo selection using the antibacterial drug, trimethoprim, where the water content of the media is decreased by increasing concentrations of sorbitol. The ability of wild type and mutant clones of R67 DHFR to allow host Escherichia coli to grow in the presence of trimethoprim plus added sorbitol parallels the catalytic efficiency of the DHFR clones, indicating water content strongly correlates with the in vivo function of R67 DHFR.
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Affiliation(s)
- Shaileja Chopra
- Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, USA
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